Translated by Pavel Volkov
Edited bt Timothy Donald Morris

In the memory of mankind, North Africa has turned from a wet savanna into an arid Sahara desert. In the Neocene epoch, this area changed: the Nile turned west again, and now irrigates a significant area of North Africa, and along its banks there is a savannah with some areas of forests in the floodplain of the river. The climate of North Africa has also changed, becoming milder and more favorable for life: it is seasonally wet, and rain clouds come from the Tanganyika Strait. The period without rains is relatively short.
In such conditions, exuberant vegetation grows: the grass stretches up to a height of 2 meters. In some places in the savannah there are even swamps that dry up in the dry season.
Such conditions are very favorable for the rapid development of life. The African savanna abounds with large animals. Herds of large beasts – flathorns – graze everywhere. These mammals lazily chew grass, shaking their heads, armed with wide horns. The beasts seem half-asleep and sluggish, but they are always on the alert. Even such giants have an enemy – they are hunted by saber-toothed deadlynettas. Occasionally, the spotted back of this merciless predator flashes in the tall grass. Startled by a saber-toothed hunter, herds of graceful harelopes rush across the grass like the wind. There is a hum of voices above the savannah: the flathorns that have spotted the saber-toothed predator roar, and they are joined by a deafening cacophony of cries of furiobaboons, who also noticed the deadlynetta and prudently climbed a tree.
The rampant grass partially obscures the field of view of all these animals, but one of the inhabitants of the savannah notices any predator from afar from the height of its height. Previously, giraffes – representatives of hoofed mammals – had such an advantage. But now their place has been taken by a tall bird – a giraffe ostrich.
A tall giraffe ostrich male browses acacia branches. Its firm beak allows the bird not to be afraid of thorns, with which this tree has successfully discouraged almost all lovers of foliage for millions of years. Stones in the stomach of a huge bird grind greens like millstones.
Noon is coming. After eating, the male returns to the nest arranged among the bushes. The male incubated the eggs all night, and in the morning he was replaced by a female. The first half of the day passed quietly, but now the female on the nest behaves restlessly: she constantly jumps out of the nest and places her throat against the eggs. The thin skin on her throat helps the huge female bird control the condition of the eggs. This is especially important at this time, because an addition is planned to the family: incubation has come to an end, and the hatching of chicks is already beginning. From the eggs, the squeak of ready-to-be-born ostrich chicks is heard more and more clearly, and the eggs shudder slightly when the chicks begin to hatch. But it is impossible to get out of an egg with a strong shell so easily: the first chicks emerge from the eggs only in the early morning of the next day, after a whole night of hard work.
The newly hatched chicks are wet and helpless. The female warms them, and the huge male keeps watch near the nest. The newly hatched chicks are already in danger: a family group of furiobaboons is hiding in the bushes nearby, waiting for the birds to be distracted to steal one or two chicks. These monkeys are carnivorous and very inventive in ways of getting food, but this time they do not dare to approach the nest. When the male rushes at them, stamping his feet, the monkeys rush away with a heart-rending squeal. Even a deadlynetta would not dare to attack these birds now – driven by parental instinct, the male would most likely attack her himself. At night, the male sits at the female’s side, and the parents warm their chicks together. In the morning of the next day, the young ostriches have dried off, are firmly on their feet, and are ready to leave the nest. Their parents take them into the world of the savannah, full of food and dangers. The nest is abandoned, but some eggs seem to have remained intact. Furiobaboons are waiting for such a moment: it happens that a female who decided to lay eggs too late laid her eggs in someone else’s nest, and they simply do not have time to finish the development. The monkeys hurry to the nest, but they are in for a big disappointment: they have already been outpaced. Monkeys push eggs with their paws, and they roll surprisingly easily. Upon closer examination, it turns out that the eggs only seemed whole: small holes were drilled in the shells, and the remnants of the contents had long since dried up. Disappointed monkeys leave the nest and go home to look for something more edible.
The eggs of the giraffe ostrich were carefully drunk through small holes – it is the work of one of the unusual inhabitants of the savannah, the African egg-eating drillsnake. This snake specialized in ravaging the nests of ostriches, and is so skillful in it, that the bird does not even notice that the enemy is in the nest right under it. The snake digs under the nest, using the burrows of rodents, or digging its own ones, and for several hours sucks the egg dry, quickly digesting its contents. Usually the attack occurs at night when the hatching bird is sleeping. In each nest from one to three eggs are sucked out by this inconspicuous robber. Another evidence of snake attack is that half-buried burrows are visible under the nest. Obviously, some small rodent dug a hole under the nest of birds, and the drillsnake used it to attack the nest.
Giraffe ostriches walk along the savannah with their brood. The birds are quite massive, and their hoof-like claws leave deep footprints in the ground. The footsteps of huge birds echo loudly on the ground, and for the small inhabitants of the savannah, this is an alarm signal. Small animals hide: large birds, especially their chicks, sometimes diversify their diet with food of animal origin, and simply peck various small animals. A large giraffe ostrich is able to swallow effortlessly a whole cat-sized animal. Therefore, having heared the footsteps of giants, various snakes and lizards try to hide in burrows or in tree hollows.
The body of the “grass fish” – a lizard with deep laterally compressed body – slides in the grass. It moves so deftly that its movements are almost invisible to an outside observer. The lizard literally bends around each tuft of grass, trying not to touch the blades of grass once again so that their waving does not betray the reptile. Fleeing through the grass, lizards of this species close their eyes, but thanks to the transparent lower eyelids, they perfectly see where to run. About a dozen of these agile reptiles run away from under the feet of the giraffe ostrich. Only here and there, for a split second, the ostrich notices a tiny bright patch of the gular sac of one of the lizards. A huge bird accelerates its measured step for a second – its huge foot crushes one lizard, like a multi-pound hammer. There is a faint crunch of bones and the rustling of grass from the convulsive movements of the tail of a dying lizard. The giraffe ostrich removes its foot from the smashed reptile, bends down carefully, grabs the lizard carcass with its beak, throws it up and catches it headfirst. The bird swallows the prey whole and again assumes its former indifferently dismissive appearance. An adult giraffe ostrich is one of the lords of the savannah. If it manages to survive in young age and survive at least the first two years of life, its adult life becomes fully safe.
But as invulnerable as the adult giant of the savannah is, as defenseless its offspring are. The chicks of the ostrich giraffe leave the nest on the second day of life and begin to live a completely independent life. They need protection from the side of Mom and Dad the most.
It is very warm in the savannah, and in the sun the temperature rises almost to forty degrees. Therefore, young birds need a parental shade rather than heating. Unless at night they hide under one of the parents.
Rather large “chicks” covered with thick golden down with longitudinal black stripes are active and independent. They search for food on their own, tasting everything that moves. The female only sometimes drives her chicks away from bushes with poisonous leaves. But she can’t keep track of the whole brood, and some chicks get into trouble because of their excessive independence. One of the chicks was carried away by the chasing of the lizard, lagged behind the brood and completely lost in the dense tall grass. It tries to find its parents and the rest of the brood, but only gets more lost – it moves in a completely different direction. For a split second, it sees its dad’s head in the distance, casually tearing a leaf from a tree. This gives the chick determination, and it begins to squeak and call its parents. It seems that it was heard: a hefty lizard with a flattened head rises from the grass. For a few seconds, the reptile stands on its hind legs, swaying a little bit, and turns its head in the hope of more accurately detecting the direction from which the voice is coming. A few quick “shots” of its forked tongue, and the direction from which the smell of prey comes is determined. The reptile, which looks like some kind of dinosaur, falls on all four paws, and begins to search for a chick. This animal is a robber monitor lizard, a terror of all small and medium-sized animals and the main danger for the giraffe ostrich chicks.
Making its way through the grass, the reptile does not see the chick and searches for it in the grass solely by ear and smell. This is a difficult task: the giraffe ostrich chicks immediately upon hatching have a camouflage coloring, and they are very difficult to notice, especially if the chick freezes in the grass. But the reptile is led to the hidden chick by its sense of smell, and, in addition, the chick continues to desperately call its parents. It is not far away: the monitor lizard has seen the head of the giraffe ostrich chick flashed among the grass several times. But today it will not manage to attack this chick – the giraffe ostrich male from the high vantage point notices both his offspring and the danger threatening him. The bird quickly steps towards the chick, and stands between him and the monitor lizard. The reptile darted to the side, trying to get around the ostrich out of reach of its legs, that deliver crushing blows. But the ostrich sees that the enemy has not run away, and stomps his feet. It is impossible to think of a more formidable and effective warning: the monitor lizard immediately runs away, fearing being maimed by an angry bird. The chick has found its father, and the huge bird leads it to the rest of the brood. The female drives the brood together, and the birds continue their measured life.
Feathered giants live in their own world, and they hardly care about small creatures rustling in the grass, especially if the bird is not hungry. But the little inhabitants of the savannah have to reckon with the presence of giants in their world, so they hide or run away when the giant bird’s feet step on the grass.
The grass seems uninhabited, but this is a deceptive impression. When the footsteps of the giant bird subside, some of the stems move, and what seemed to be a dead dried leaf turns into a quite alive being. Stick-like agamas, thin fragile lizards, crouched among the stems, frightened by the steps of the bird. When such a striped lizard presses itself against a graminoid stalk, it is so invisible that it seems to be part of it. In this position, clutching the grass with their digits, lizards can stay for a long time. Only at the most critical moment does the lizard decide to flee.
The giant ostrich has passed, and so has his brood. Now tailed invisibles can “come to life”. Confident in their safety, lizards begin their fussy life: they climb stems, hunt for flies and beetles and quarrel with neighbors. At the same time, barely audible clicks are heard here and there, as if chips are breaking – these are males declaring their right to territory to each other. Doing it, the male that drives away its opponent swings on a blade of grass, displaying its gular sac to the stranger.
Stick-like agamas have an interesting way of moving: they often jump from one stem to another sideways, pushing off simultaneously with their front and back paws on the same side of the body. Although they are reptiles, they are as agile as monkeys. Frightened, they deftly hide in the thick of the grass and freeze. It is almost impossible to find them at this moment.
A lone stick-like agama moves through the grass thickets. It deftly jumps from one grass stem to another, snatching them with its front and hind legs. But one of the stems, on which the lizard was about to jump, quite unexpectedly begins to move. The lizard runs away in fright and hides. The “stem” behaving so unusually turns out to be the body of a cricket snake. Due to the longitudinal striped coloration, this snake ideally hides among the grass from large predators. Frightened by the unexpected appearance of this reptile, stick-like agama quickly disappeared into the grass. But the cricket snake is not interested in lizards – it hunts small prey. This snake is not very dangerous for adult stick-like agamas, although, if possible, it willingly eats their juveniles.
At noon, the savannah is sweltering with heat, and a haze trembles in the air. This is not the time for mammals: the savanna is at the mercy of reptiles. Even the birds are hiding somewhere in the shade. But the grasshoppers arrange their deafening concert. Their chirping blends into the uniform continuous smooth sound background, and it seems, there is nowhere to hide from it.
The cricket snake is a master of grasshopper hunting. Noticing an insect, the snake slowly creeps up to it, making a “stand” on its tail. The back of the body of this reptile is more massive than the front part, and the snake easily performs such a trick. Swaying from side to side, it distracts the attention of the grasshopper, and then grabs it with a quick rush. Working with its jaws, the snake as if “chews” the caught insect. When doing it, the reptile crushes the shell of a grasshopper and at the same time tears off the inedible wings and stiff hind legs. A cricket snake can eat up to a dozen of these insects in a day.
Harelopes rest in the shade of bushes: mammals tolerate heat worse than reptiles. Large predatory beasts are also inactive in the heat, and harelopes are relatively safe. These herbivores find a shaded place in bushes or under a tree, and lie with their legs stretched out freely and from time to time plucking and chewing leaves. Usually they rest in small groups, and then one or the other animal listens and carefully looks around the neighborhood, trying to notice the approach of predators in time.
Animals try to hide in the heat, but this is the best time for reptiles to hunt. The robber monitor lizard often uses its physiological advantages in hunting: it is most active in the midday heat. A giant lizard wanders through the grass on erect limbs – so the monitor lizard can see farther. The head on the flexible neck can easily turn in any direction, and large eyes are sensitive and easily distinguish small details even at a great distance. The lizard tries to determine the presence of suitable prey. But the tall grass worsens the view, and for some seconds the monitor lizard stands up on its hind legs with a little effort to look around.
The acrobatic trick helped: a robber monitor lizard notices resting harelopes under the bushes. Its yellowish skin does not stand out very much against the background of slightly yellowed grass, and the harelopes did not see the reptile. The robber monitor lizard starts hunting them. But it will not be a long chase, like a wolf does, or a short quick rush of a cheetah, or a crushing attack of a tiger or bear. The robber monitor lizard, without speeding up its pace, goes to a group of resting harelopes. Of course, after some time, one of these animals notices an approaching monster, and gives an alarm. All the harelopes jump up and quickly run away. But the reptile knows from its experience that they cannot go far: they seek to hide from the sun again. When the harelopes lie down in the shade, the monitor lizard continues its chase. Without speeding up its movement, the lizard steps towards them, and the frightened harelopes are again forced to seek shelter. This situation repeats several times. The movements of the monitor lizard do not indicate the stupidity of the reptile at all: it acts purposefully. It notices which of the animals try to lie down in the shade as early as possible, and its attention is focused on them. The monitor lizard is not interested in large and hardy animals, hunting for which is a senseless waste of time and effort. But the female and the cub just match its interest. The female is strong enough, but her cub shows weakness, and the monitor lizard noticed it. From stayless runs, the cub has overheated in the sun, and feels very bad: it staggers, and can no longer keep up with its mother. And now the main task for the predatory lizard is to isolate the cub from its mother. The female guarding the offspring can inflict sensitive blows to the predator with her front legs, so the robber monitor lizard tries not to approach her. The monitor lizard continues its chase, and now the moment comes when the cub has lagged behind the female. The reptile, taking advantage of the opportunity, rushed to intercept it, and half the work was done: the cub and the mother were separated. After that, the monitor lizard no longer pays attention to the female, but begins to exhaust the cub with continuous chasing. When the female tries to come to its aid, the monitor lizard rises on its hind legs and takes a few steps towards her, snapping its teeth. The frightened female retreats, and the monitor lizard continues its attack.
The chase does not last long: the cub soon stumbles, the robber monitor lizard pounces on it and clings to the throat of the prey. For some seconds, the harelope cub wheezes and kicks, but the monitor lizard shakes it and breaks its neck with one powerful jerk.
The female hare cautiously squints at the reptile, which holds the body of her cub in its teeth. When a small body falls from the teeth of a monitor lizard into the grass, she leaves: the cub does not call her and does not move. The parental instinct tells her nothing, and the instinct of self-preservation tells her to leave it.
The monitor lizard begins to eat. With the claws of its front paws, it tears apart the prey, and with its teeth it tears out large pieces of meat along with bones, and swallows them, convulsively twitching its neck. Usually, the monitor lizard eats only the soft tissues of the limbs and insides: its teeth are not adapted for gnawing meat from the ribs. Soon, the predator eats to the brim and moves away, leaving the head and slightly gnawed chest of the harelope cub in the grass. The reptiles’ metabolism is not very fast, and it will have enough of such a lunch for about two days.
There is still enough meat left on the bones of the harelope cub, and the remains of the prey of the robber monitor lizard literally turn black from the multitude of flies that have flown to the free treat. Insects buzz over the torn carcass, choosing places for laying eggs. In addition to them, several carrion-eating beetles come to the smell of blood. But when the footsteps of the robber monitor lizard died away in the distance, creatures that are larger than insects began to gather to the carcass. Several stalks of grass moved almost noiselessly, and the head of the “grass fish”, crowned with a leathery crest, appeared from behind them. The lizard quickly looks around, and starts hurriedly eating the remains of meat. Time is running out: other carrion lovers, including its congeners, can gather for the smell of meat. The “grass fish” bites the meat left between the ribs of the prey: the jaws of the robber monitor lizard are well suited to cut and tear soft tissues, but are not suitable to gnaw bones clean. Therefore, there is something to profit from here.
Another “grass fish” appears from the grass, clearly expecting to a free treat. But the right to the plentiful meal still needs to be earned... Lizards are in no hurry to get into a fight, and try to establish primacy with ritualized movements: lifting their heads up, both lizards open their gular sacs and begin nodding their heads. They stand one parallel to the other so that the opponent can see all the splendor of the coloring of the throat of the opponent. One of these lizards is male, the other one is female. The “grass fish” male has a clear advantage: he is larger and stronger, so the female does not continue the competition, folds her gular sac and runs away. However, the male also does not have long to feast alone: the echoing footsteps of the giraffe ostrich are heard through the ground. The huge bird has not noticed the “grass fish” yet, but the lizard wisely hides in the grass and runs away from this feathered giant. The ostrich browses leaves from trees, but it does not mind diversifying its diet with small animals, so occasionally the bird glances at the ground. Having noticed the remains of a harelope cub, the bird picks them up with its beak and swallows them along with the bones. The feast is over.
The giraffe ostrich moves on. But something remains after the feast of predators: the grass is stained with blood, and flies continue to hover over this place. From time to time they alight upon the grass, licking off the remnants of blood. But a young “grass fish” jumps out of the grass and starts hunting them. Not a single part of the animal that died in the savanna is wasted.
In the afternoon, the heat subsides gradually, and the animals become more active. A brood of giraffe ostriches, accompanied by their parents, goes to drink at a wide shallow river flowing into one of the tributaries of the Sahara Nile. The mother leads the chicks, and the male drives the stragglers and inspects the area in order to detect possible predators ahead of time. But the only creatures he sees so far are the harelopes. A small herd of these mammals follows the ostriches, kicking up dust with their thin legs.
When such giants go to drink, the inhabitants of the river feel their approach ahead of time. The stamping of their feet is clearly audible under the water, and the fishes try to swim away from the shore. Another inhabitant of the river swims out of the reeds: it is a river adder frightened by the approach of giants. Flashing its silver striped sides, the snake swims away from the water-drinking giants: an ostrich can easily peck it. With a thin squeak, the snake inhales air, swims near the surface of the water for a while, and then closes its nasal valves and dives. Scaring small fish, the river adder swims to the opposite riverbank. It feeds on fish, so it tries not to be in sight of possible prey for too long. Having chosen a suitable place in a well-warmed shallow water, the river adder buries itself in the silt by lateral movements of its body. Now it can only wait for the river to carry away the churned silt. This snake can hold its breath for a long time, remaining motionless in ambush.
When the herbivores leave, the river dwellers continue their lives. In shallow water areas, where the water is warmed up strongly and is well illuminated by the sun, the bottom is densely overgrown with blue-green algae. Slimy films of bluish-green color hang on snags and plant stems like a fringe. They literally strangle the small shoots of aquatic grasses, blocking the sunlight to them. But this situation does not last long: there are big large-headed fishes of a soft color in the reservoir. These are algotilapias – algae devourers. Like lawn mowers, they scrape the slimy films with their mouths, carefully scraping them from plants and driftwood. An adult algotilapia weighs slightly less than a river adder, and the reptile hides deeper in the mud when one of these fishes swims nearby.
Algotilapias are peaceful herbivorous fishes. They do not pay attention to small fish of other species, but they prefer to keep a safe distance from their own congeners. Fishes of this species feed at a distance of about 6-7 meters from each other. If one of the large congeners accidentally crosses the border between individual plots, the owner of the territory swims out to meet it, stretches its fins and makes it clear to the uninvited guest that the territory is occupied.
There are not only adult fishes, but also juveniles in the schools of algotiliapia. Young fishes of this species stand in the most unenviable position in the hierarchy of the local population. They have not yet conquered their living space, and therefore feed stealthily on the “nobody’s” border strip, from time to time getting pokes from legitimate owners on both sides. These small fishes make a tasty prey for the river adder.
Algotilapias are quite slow, and it is not difficult to catch such a fish. The snake leans out of the mud and waits until a suitable-sized fish swims to the distance of the successful rush. The river adder opens its mouth slightly, and sensitive cells on the mucous membrane feel waves from swimming fish even in muddy water. When one algotilalia about a third of the length of an adult fish begins to scratch the bottom with its mouth right in front of the adder’s head, the snake gives it a lightning bite in the side. The fish jerks convulsively and breaks out of the mouth of the snake, which, however, did not try to hold its prey very tightly. Fish’s congeners from neighboring plots rush to the sides in fright. The bitten fish swims a few more meters. In order not to lose prey, the river adder leaves its shelter and follows it. Gradually, the poison begins its action: the algotilapia weakens and emerges to the surface of the water. Blood begins to ooze from its gills: the venom of the adder began to destroy the red blood cells of the fish, and blood plasma stained with hemoglobin seeps through the gill epithelium. After another minute, the algotilapia loses its balance and swims belly up in circles. “lunch is served”: the river adder grabs its by the head and swallows it with some effort. The adder waited until the fish died so as not to injure itself: there are poisonous spikes in the dorsal fin of the algotilapia, and the fish, while still able to defend itself, can kill the river adder with a fin prick.
The adder is full, and the outlines of the swallowed fish are vaguely discernible in its stomach. It stops hunting, and for the next few days it will not feel hungry. Now it only needs rest: a well-fed snake becomes slow. Having finished with the prey, the snake emerges to the surface of the water, takes a breath, and dives again. It lies down on the bottom and slightly buries itself in the silt to be not found by predators. The algotilapias, which rushed to the sides at the moment of the snake attack, calm down and continue their work on cleaning the river bottom again. The clouds of silt that have risen above the hidden snake attract several algotiliapias. One of the fishes, swimming next to the adder lying on the bottom, touches its head. The snake lazily crawls out of the mud and swims, ignoring the large fishes engaged in feeding. It hides in the reeds, where it will spend the next few days digesting prey.
Other snakes are in a worse position than the river adder because of their stict food specialization. These are, for example, drillsnakes, the egg eaters. The main food of this species, the eggs of giraffe ostrich, is a very seasonal kind of food, available only some months a year. The rest of the time, the drillsnake feeds on the eggs of other animals, or economically consumes the fat reserves accumulated during the period of feeding on the eggs of the giant ostrich. When giraffe ostriches hatch chicks, the drillsnakes live practically half-starved, although it does not harm their health.
And yet, even such a highly specialized gourmet can find prey. The drillsnake, a large yellowish snake with a “marble” skin pattern, crawls along the sandy bank of the river in search of reptile eggs. From time to time, the snake raises its head and collects traces of odorous substances floating in the air with rapid movements of its tongue. The sense of smell of this snake is very subtle, and for the reptile it worth nothing to find a clutch of turtle eggs buried in the sand.
It looks like the snake was lucky: it smells a newly made clutch. Shaking its head from side to side, the drillsnake tries to more accurately detect the location of the source of an attractive smell. There is indeed a turtle nest under the sand at a depth of about half a meter: it was built by a huge crocoturtle, a ferocious predator, the largest of African turtles. If this reptile with a length of about four meters was guarding its nest, the drillsnake would have a bad time: the crocoturtle feeds on large animals, so killing and eating this snake is a trifling task for it. But the crocoturtle does not change the traditions of its ancestors, and does not care about its own offspring at all. A hungry turtle of this species can freely eat its own relative.
After making sure that there are no competitors around, the drillsnake buries itself in the sand at some distance from the turtle nest. This snake feeds quite slowly, so it is forced to hide during the meal from predators that can attack from the surface of the earth (and when a drillsnake robs the nest of a giraffe ostrich, it also have to be afraid of parent birds). The reptile drills through the thickness of sand with large teeth protruding forward, rotating its head from side to side. From time to time, the snake stops and carefully sticks out its tongue, checking whether the direction of digging is chosen correctly. It seems that the snake was not mistaken: after half an hour of work, the sand in front of its head becomes looser, and the smell of eggs becomes more distinct. Some more movements, and the tongue of the drillsnake touches the shell of the turtle egg. The drillsnake eats only fresh eggs in which a large embryo has not had time to develop: the digestive system of this species is adapted for the consumption of liquid food, and the most attractive part of the egg is the yolk. By the smell, the snake determines that the clutch was made only three or four days ago. Such eggs are quite suitable, and the drillsnake starts eating. Sharp teeth protruding forward, break through the shell of one of the eggs. Slightly tilting its head to the side, the snake expands the hole in the shell, and its movable pharynx is used. The throat of the drillsnake can turn out of its mouth like the stomach of a starfish. The flexible tube of the pharynx penetrates into the egg, and first of all begins to suck out the nutritious yolk. Egg white is also used: it contains a lot of water, and the reptile quenches its thirst with it. When one egg is finished, the drillsnake turns its head and opens the next egg. Gradually, the reptile sucks out all the turtle eggs one by one. Having had enough, the drill snake carefully “puts in place” its throat, and begins to drill a burrow to the surface of the sand.
Drillsnakes do not form dense settlements, because their food is very specific and does not occur in mass quantities for a long time. But on the territory of one adult snake, several young ones usually live. They feed on small bird eggs, and do not compete with an adult snake. But at any age, the smell of eggs is attractive to these reptiles. Therefore, the tunnel dug by an adult drill snake is empty for a short time.
Attracted by the smell of a ravaged turtle nest, a young snake of the same species crawls in the hole. Juvenile drillsnakes are armed with the same sharp teeth as the adults. The first food of a young drill snake is the eggs of small birds. But in the sand on the river bank, it is possible to find more attractive prey – turtle eggs.
A young drillsnake, often sticking out its tongue, examines eggshells emptied by an adult snake. And, it seems, it is incredibly lucky: a young snake finds one egg, accidentally left by an adult drillsnake. This may be the first turtle egg it has tasted in its short life. The teeth of a young drillsnake dig into the calcareous shell of an egg. The sand around the egg is too loose, so the body of a young snake only crushes it, and its teeth slide on the shell, rather than pierce it. But soon, when the sand thickened, the snake rested its body rings against the wall of the hole, pressed with its teeth, and the shell burst. When the sticky egg white seeped out of the crack, the drillsnake turned its head slightly and widened the hole. Opening its mouth to its full width, the snake clung to the crack in the shell, and turned its throat inside the egg. The muscles of the neck and the ring muscles of the pharynx began to contract rhythmically. In order not to suffocate during the feeding process, the snake pushes the tip of its trachea forward, pressing it from the inside to the nasal openings.
While a young snake is eating a turtle egg in a sand hole, an adult drillsnake, heavy with drunk eggs, crawls in the savannah in search of shelter. Digestion in the drillsnake occurs faster than in other snake species. Egg yolk fats are especially quickly absorbed. But the main condition for successful digestion is complete rest. Therefore, having found its hole under the roots of acacia, the drillsnake hides in it. The reptile will spend a few days in it, digesting food, and then crawl out to feed again. It doesn’t matter if it will fail to find food: a well-fed adult drillsnake can starve without harm until next year, when giraffe ostriches will start nesting again.
It gets dark quickly in the tropics, and a warm night falls on the savannah. Diurnal animals hide, and nocturnal animals come out to replace them. The night in the savannah does not pass in silence: it is resounded by the voices of various kinds of crickets and cicadas. Crickets are lovers of singing in choir, but each of them still renders a solo party: male crickets do not tolerate competitors, and if two males choose the same stem, a fierce fight ensues between them, after which one of them may even be eaten by the winner. The vocalizations of insects are diverse: some of them chirr, others chirp, and others produce a monotonous dry trill. Sitting on grass stalks, some of them perform such loud trills that even a deaf person seems to hear them. However, one deaf person is just trying to listen to the voices of six-legged musicians in its own way: at night, the cricket snake goes hunting again. In the dark, vision is a bad helper, but the snake has one more trick in stock. Sound easily passes through solid objects, so even a snake with its reduced hearing apparatus will be able to learn about the presence of a singing insect. The cricket snake puts its throat to the stem and catches the vibrations of the cricket, selflessly singing a love song, with its sensitive skin. It is unlikely that it was alerted when the stem swayed slightly under its legs. But it costs the insect its life: with a well-aimed rush, the cricket snake grabs it. However, this is only good for its neighbors: they begin to chirp with a vengeance, having lost a competitor.
At night, large herbivorous animals huddle together in dense herds and sleep, slowly chewing their rumination. The flathorns become sluggish and stand among the grass like statues. They sleep lightly, but for a long time. Sometimes animals wake up, look around for a while and shake their ears, after which they fall asleep again. Harelopes spend the night next to the giants. These animals, on the contrary, sleep fitfully, but in a deep sleep. Both of them sleep standing up – so it’s faster to escape from a sudden night attack. Giraffe ostriches fall asleep in different ways: the male, having gathered his naughty brood under his body, sleeps sitting on the ground and putting his head under his wing. Occasionally, the head of a chick with sleepy eyes appears from under his wing. After looking around, the chick hides again under the parent’s wing. And the giraffe ostrich female sleeps lightly standing up most of the night: she must be ready to quickly repel the night attack of predators. Only at dawn the male replaces her.
Stick-like agamas become sluggish in the cool of the night. They hang on the stems, clinging to them and trying to be as inconspicuous as possible – at night their life processes slow down, and it is much more difficult for them to escape. Therefore, it would be better if they are simply not noticed.
However, there are animals for which night is a time of active life. At night, various rodents come out of their burrows and nests for feeding. The stalks of graminoids sway in some places, and the songs of crickets interrupt by the squeaking and chirping of rodents scurrying in the grass. Such a variety of game simply cannot fail to attract various predators. Therefore, from time to time, the frightened crickets fall silent, and the rodents scatter when the voice of one of their relatives is replaced by a desperate squeak and abruptly ends.
In the night darkness, along with the mammals, some reptiles hunt. Some of the snakes find rodents in burrows, and others find them by smell. But one African snake species has developed in the process of evolution an amazing adaptation that allows it to freely notice rodents even in pitch darkness. A rodent can be silent; it can hide its smell; it can cling to the ground or hide in the thick grass, but it cannot hide the warmth of its body. This weakness of rodents is used by the thermovisor viper, a snake that goes hunting at dusk.
Probably, the world looks strange in the eyes of a thermovisor viper: what is invisible to the ordinary eye appears clearly distinguishable for it. The reptile bypasses large animals, which seem to be light figures against the background of cool dark air. The snake itself is afraid of them: it does not want to be crushed by the feet of an unsuspecting, half-asleep flathorn. And the sharp hooves of a harelope can injure this snake. Of course, thermovisor viper can kill any large animal with its venom to save its life, but this is of little use: the snake does not care if the animal is killed when it is crushed itself. Therefore, it tries not to approach the giants of the savannah.
But a meeting with small mammals is a welcome event that does not have to wait long. There are many kinds of various rodents in the savanna. These are mostly mice and small hamsters. During the day they keep in burrows, and spend the night in search of food. The thermovisor viper does not hear their rustling in the grass, but it perfectly feels the vibration of the soil from their light steps. The snake does not always look for prey itself: sometimes it is more expedient to just lie low and wait patiently.
The viper did not have to wait long for the appearance of prey: small rodents, obviously some kind of mice, got out of their burrows and feed in the grass. Unaware of the danger lurking nearby, they go about their normal lives: running after each other, dragging spikelets and peeling grain from them. But they frolic a little far from the viper, and the snake creeps closer. The scaly body of the viper sneaks among the grass. It moves almost noiselessly, but still the mice with their acute hearing are on the alert. The enemy does not walk around the savannah, loudly declaring its presence, and if it does, it means that it simply does not hunt. But a quiet, almost inaudible rustle is the most terrible of sounds for any animal, especially a small one. Hearing the rustle of the scales of the viper on the stems of the grasses, the mice freeze and cling to the ground. This is a normal defensive reaction – they try to become invisible and inaudible. So they can hide from the sight of nocturnal predatory animals or most snakes, but the thermovisor viper sees them perfectly – the thermal radiation of rodents is relatively high, their body temperature is high, and they stand out as “bright” spots against the background of grass. The snake chooses a target to attack – a large mouse that has frozen away from the others. A few movements of the tongue to clarify the target, and the snake throws itself at the intended prey with lightning speed. A bite follows, and the rodent jumps high into the air. The mouse tries to hide from the predator: having made a few long jumps, it goes out of sight of the snake. But its efforts are in vain, and the minutes of its life are already numbered – they are just enough to make a few jumps, but no more.
The snake crawls along the odorous trail, occasionally tasting the air with its tongue, and soon finds the lifeless body of the rodent. In the eyes of the thermovisor viper, it is already beginning to “fade”: the carcass of the killed mammal is cooling down. Opening its mouth and spreading its jaw bones, the snake swallows it whole. The hunt is over, and now the thermovisor viper will not leave its shelter for several days. Now the most important thing for it is to get home before dawn, before the huge inhabitants of the savannah wake up.
The morning in the tropics is short: the sun rises almost in a vertical line, and it dawns very quickly. In the short hours of dawn, there is a “change of scenery” – nocturnal inhabitants hide, giving way to diurnal ones. When it gets light, night terrors, creeping on soft paws, or rustling in the grass, go away. The animals wake up, stretch and prepare to survive another day.
Furiobaboons spent the night in a tree. They fill the savannah with loud screams, letting everyone know that they are alive and well. The flathorns push each other with their horns and rub their muzzles against each other, as if greeting their relatives again. One of the giants takes a morning dust bath – it happily wallows on the ground and purrs like a cub during a game. When one of its relatives approaches it, a large animal jumps to its feet, and the giants of the savannah “greet” each other by sniffing the back of a relative in the place where the odorous glands are located.
Somewhere in the distance, the roar of a saber-toothed deadlynetta is heard. Herbivorous animals don’t worry: this means that the predator does not care about them yet. Early in the morning, this viverrid has already preyed one harelope, and now it will spend the day in idleness and rest, only occasionally driving away from the remnants of its prey some especially impudent scavengers.
It’s getting light fast, but not all nocturnal animals have hidden yet. The thermovisor viper is searching for a shelter to calmly digest its prey. It needs to hide as soon as possible so as not to become an accidental prey of one of the predators. And such an undesirable meeting is already coming. Giraffe ostriches with chicks have been awake for a long time and are already actively looking for food. The chicks of these giants are still stupid. Not having enough life experience, they are ready to consider edible and peck everything that shows signs of life and is not too large. One of the chicks noticed a thermovisor viper crawling among the grass. Not realizing the danger of such a meeting, it gets too close to the snake and pecks its tip of the tail. The snake immediately curls into a spiral, taking a defensive position. This warm silly creature covered with down is too big to become its prey. In addition, the snake is full and has no desire to face anyone. Therefore, the viper is in no hurry to attack the ostrich chick. It stands up like a cobra and emits a loud warning whistle, blowing air through slightly compressed lips. The chick does not yet understand the meaning of this sound, but its mother has already seen in her life how her relatives, who did not retreat from this snake, lay down on the ground after its bite, so as not to get up again. Therefore, she makes an alarming sound and gathers her chicks together. The male also heard this signal, and stood between the brood and the snake. He does not approach the dangerous reptile, but stamps his feet, making it clear that he is ready to protect the offspring. The thermovisor viper hides in the bushes – away from the raging giant. The birds also leave – the female in front of the brood, the male behind it, carefully hastening the chicks scattering to the sides. He does this for a reason: a large robber monitor lizard follows the brood at a respectful distance. If one of the chicks gets lost, it will most likely be lunch for the monitor lizard. Despite the efforts of the parent birds, these predators exterminate up to half of the brood during the first two months of the life of the ostrich chicks. Even young birds that have reached almost two meters in height cannot feel safe: adult robber monitor lizards can attack them. But usually the robber monitor lizard hunts smaller game: lizards, snakes and small mammals that can be handled without risk to life.
Hearing the rustling of snake scales on the grass, the monitor lizard ceased the pursuit of a brood of ostriches, and approached a small bush. Having stopped next to it, the monitor lizard begins to carefully examine the grass, and soon notices that a thermovisor viper has curled up in it. Monitor lizards eat vipers if they manage to catch a well-fed, and therefore insufficiently agile snake. Having prepared itself, the robber monitor lizard tries to attack the viper. The lizard acts with brute force, and the viper has two weapons: its agility and venom. But the snake digests the captured rodent, so it tends to hide from the pressing predator. The monitor lizard becomes too overconfident: it rushes at the snake, and its jaws snap a few centimeters from snake’s head. This is too much, and the viper defends itself: like a released spring, it jumps out from under the bush and stings the monitor lizard. The lizard is saved only by a lightning reaction: the monitor lizard dodges for a fraction of a second, and the bite of the thermovisor viper is glancing. The venom of this snake is dangerous for the mammals it feeds on, but it acts much less effectively on reptiles. The monitor lizard could not completely avoid the snake’s attack, and received a prick from one of snake’s teeth: its shoulder is scratched. A small amount of poison got into the wound, and the monitor lizard feels bad. The reptile becomes more sluggish, staggers and moves away. The viper, seeing that the predatory lizard is retreating, emits a loud warning whistle.
Staggering, the robber monitor lizard wanders through the savannah and hides in the bushes. Its high immunity to poisons will help it survive. It will recover in rest for a few hours, and it will go hunting another time. Most likely, after this meeting, it will bypass snakes that emit a loud warning whistle.
Life in the savannah does not cease day or night. Animals hunt each other, hide or defend themselves. This is one of the engines of evolutionary progress that determines the appearance and behavior of living beings. Evolution is the sum of the successes and losses of all living individuals.

Short-headed algotilapia (Algotilapia breviceps)
Order: Percoid fishes (Perciformes), suborder Labroidei
Family: Cichlids (Cichlidae)
Habitats: Saharan Nile, lower reaches of the Nile-Niger system.

Picture by Arseny Zolotnikov
Colorization by Carlos Pizcueta

In nature, the phenomenon of convergence is very common, when in similar living conditions unrelated species develop features of superficial similarity associated with adaptation to the habitat. This happened in Africa, in the middle course of the Nile in its Saharan part. Here the river forms many shallow branches and channels with a slow current. Such reservoirs, well warmed up and illuminated by the sun, repesent a favorable place for the growth of a large number of algae. The bottom in such water bodies is covered with a thick green carpet of filamentous algae; films of blue-green algae grow on the stones, and sometimes the water becomes cloudy because of microscopic green algae. In such reservoirs, a peculiar ecosystem develops: small flamingo ducks (Nasoanas) feed on algae from the surface of the water, and branchiopod crustaceans feed in the water column. But the largest ones among the algae eaters are large greenish-brown fishes, diligently scraping the bottom and peeling off the algae film from it. They also “mow” meadows of filamentous algae with their jaws. Their heads are short, as if chopped off, and fins are wide and rounded. These fishes are algotilapias, descendants of omnivorous tilapia fish, widespread in Africa in the Holocene.
Algotilapia is a relatively large fish that feeds on algae. The body length of an adult specimen reaches half a meter, and the fish weighs up to 5-6 kilograms. The trunk of the algotilapia in its anterior part is triangular in cross-section, with a flattened chest. The caudal fin is fan-shaped, short and wide. The head is deep, and the eyes are located in its upper part, directed up and to the sides. The mouth of the algotilapia is modified due to the specific diet of this fish: it is shifted downwards, and can open wide, stretching into a sucker with numerous small teeth growing out in several rows.
Algotilapia feeds exclusively on algae, scraping them off rocks. Since such food does not require a high speed of movement, this fish is a pretty bad and lazy swimmer. Algotilapia has a deep body and fan-shaped fins. Since this fish often feeds in shallow water, where it can easily be attacked by terrestrial and aerial predators, there are ten strong spikes in its dorsal fin to protect it from enemies: their prick is very painful due to the special properties of the slime secreting on them. The body of the algotilapia has soft colors in its coloration: the back is brown with green spots, the sides are dark green with a longitudinal brown stripe. The belly in fishes of both sexes is white. The caudal fin of algotilapia is wide and brightly colored: it is black with white spots and a wide border along the edge, red in males and yellow in females. With the help of the tail fin, the fish gives signals to its relatives. This is an important part of behavior of algotilapia: like most algae-eating fishes, it is territorial. Each fish occupies an area of about 30-40 square meters in shallow waters, protecting it from relatives. If a relative appears on the border of the feeding area, the owner of the territory gives it signals by stretching its tail fin wide. If this action does not stop the stranger, the fish drives it away with blows of its head. The aggressiveness of algae-eating fishes takes place due to the fact that algae grow at an approximately constant rate, and each section of the bottom can provide food for only one fish of such size. A variety of natural markers – stones, reed bushes and driftwood – serve as the boundaries between the possessions of algotilapias.
The male differs from the female in larger size and a more robust head. Large “calluses” grow on the sides of the male’s head, serving to establish dominance relationships during the spawning season. Usually large males occupy the best areas on the bottom.
In shallow water bodies, water often heats up very much, and the oxygen content in it decreases to a critical level. Then, sometimes the algae that have multiplied greatly begin to die off in mass, and the water turns into a smelly slime. It is unlikely that algotilapias would have inhabited such reservoirs if they lack the features that allow them to survive in such conditions. These fishes do not have air breathing organs (the swim bladder in cichlids is closed), but they are able to enrich water with oxygen. Emerging to the water surface, the algotilapia sticks the tip of its muzzle out of the water, takes an air bubble with its mouth, and forcefully pushes it through its gills. At this moment, a characteristic “smacking” sound is heard, which stimulates the other fishes to join this action. And then dozens of fishes swim near the surface of the pond, sticking out of the water and blowing bubbles. This action is repeated over and over again, and as a result of the activity of the fish school, conditions acceptable for fish life restore in the water. During the oxygen enrichment of water, fishes are very careful: too large or fast birds flying over the water frighten them, and the entire fish population of the pond dives headlong to the bottom.
During the spawning season, the male spawns on the border of his territory with one of his female neighbors. He digs a nest representing a hole in the mud with lateral movements of his head. When the nest is ready, the male begins to invite the female into it: at the border of the individual territory, he displays his open caudal fin, making circular movements. When the female approaches, the male begins to fold and spread his caudal fin, showing his intentions to breed offspring. If the female is ready to follow him, he becomes noticeably brighter: his back and stripe get a bluish sheen, and the dark green coloration becomes emerald green. The male “dances” around the pit, flapping his fins and making repeating movements from the female to the nest and back. The female ready to spawn examines the nest hole and makes several head movements in it: these are remnants of nest-building behavior. The female only spawns eggs and no longer takes part in the care of offspring. In one season, the male spawns twice with different females living in the neighborhood.
The male carefully guards the eggs, fanning them with his fins and driving away too curious fishes. It happens that he attacks even ducks that inadvertently swim up to the clutch. The fish jumps out of the water, scaring the birds, or simply strikes them with its head from below. Due to the male’s care, fry hatch in 2-3 days. The male takes care of them: he guards them and ruffles the silt on the bottom with his fins, helping the fry to feed. He guards the young for the first week of their life. At this time, the fry even hide in his mouth. However, because of the mouth of these fish, that is modified into a sucker, it is difficult for them to do it the way ancestral tilapia fry did in the Holocene. Therefore, they enter the oral cavity of their father in a different way: through his gills. The alarmed male strongly opens his gill covers, displaying white spots along their edge, that usually are hidden. Having noticed this signal, the juveniles rush to the gills of the male and squeeze into his mouth cavity. When the danger is over, the fry leave the father’s mouth cavity, also through his gills.
Young algotilapias feed on infusorians and worms, but after reaching a length of 20-25 mm, they switch to feeding on algae. At this time, fry schools break up, and young fishes begin to lead a solitary life in a small territory, usually inaccessible to adult fish, or at the “border strip” between the territories of adult fishes. As they grow up, they expand their possessions. At the age of eight months, with a length of about 20 cm, fishes of this species become capable of reproduction.

Stick-like agama (Bacillisaura tenuissima)
Order: Squamates (Squamata), suborder Lizards (Lacertilia)
Family: Agamas (Agamidae)
Habitat: savannas of North Africa (plains north of the Sahara Nile), tall grass.

Picture by Alexander Smyslov

The agamid family is one of the most progressive lizard families in the Holocene epoch. They have successfully mastered both forests and savannas, as well as desert areas. The latter quality allowed these reptiles to survive successfully the ice age, when large areas previously covered with forests turned into deserts. During the period when the extreme climate of the glacial epoch was replaced by the mild and favorable climate of the Neocene, agamids rapidly evolved and formed new species adapted to a variety of habitats.
In the savannahs of North Africa, that spread out on the place of the former Sahara, among the thickets of tall grasses, one of the unusual species of this family lives – the fragile and elegant stick-like agama. This is a small lizard species – the length of its body including its tail reaches only 20 cm. This agama has a very thin body and a relatively long, pointed head with bulging eyes. The legs are relatively long and grasping, adapted for climbing. The tail is thin, making about half of the total length of the reptile.
The body color of the stick-like agama is camouflage and represents thin brown longitudinal stripes on a yellowish background of the body, that blends with the color of dry grass. One dark stripe runs across the eye and masks it. During the rainy season, when fresh grass grows, the background color changes from yellow to green, and the lizard retains the ability to disguise itself. The pupil of the eye is slit-shaped and horizontal (thus, in a resting lizard, the slit of the pupil is turned vertically, improving the circular view). The iris of the eye is brown.
The stick-like agama somewhat resembles the walking stick insect in its lifestyle. It lives on plants in the same way, hoping entirely for its protective coloring and shape. This lizard keeps on the stalks of graminoids. At rest, it keeps along the stem and holds its trunk vertically. In this position, the lizard can easily climb onto neighboring stems, and even jumps sideways, simultaneously pushing off with the front and back paws of the same side of the body. In case of danger, it tries to disguise itself, hides under the leaves or clings to the stems, and remains motionless until the last moment. If absolutely necessary, the reptile flees, but at the first opportunity tries to hide again.
The stick-like agama feeds exclusively on insects, which it catches with a short rush when they crawl close enough. This lizard drinks, licking the dew drops forming on the stems of herbs in the morning. It may not drink for a long time, being content with the moisture obtained from food. Being a predator, it protects the feeding area from relatives, which it pushes sideways out of its territory. Males conflict only with males, and females with females. In general, the territories of individuals of opposite sexes can completely overlap.
The mating season of stick-like agamas is stretched for almost the whole year, interrupted only before the drought, which happens on the northern border of their range. Males notify neighbors that the territory is occupied by uttering characteristic sounds similar to the crackling of a broken twig. When a female approaches a male, he determines her readiness for mating by smell. If the female shows submission (occupies a lower position on the stem than the male), the male begins his courtship. He opens the gular sac, on which a bright red middle fold becomes noticeable, and begins to shake his head up and down. He descends to the female and stands side by side with her. After a quick mating, the animals leave each other.
In its clutch, there are only 2-3 relatively large eggs of a very elongated shape, but the clutch can repeat every month almost all year round, interrupted only during a severe drought. The female lays eggs in the very middle of a large clump of graminoid plant, in its depth, where they will be protected from accidental damage. Incubation lasts about a month. Young lizards do not differ from adults in their lifestyle, they only stay on plants near shrubs, where it is easier to hide from the hot sun, and small insects can be found. At the age of one year, they become adults.
Cannibalism is not typical for these lizards.

Striped “grass fish” (Herbichthys fasciatus)
Order: Squamates (Squamata), suborder Lizards (Lacertilia)
Family: Agamids (Agamidae)
Habitat: savannas of North Africa (from the Saharan Nile to the Atlas Mountains), tall grass areas.
Large reptiles, like Mesozoic dinosaurs and giant synapsid reptiles of the Permian period, were quite vulnerable groups of inhabitants of the Earth. But the variety of all kinds of small reptiles remained relatively large even during mass extinctions. Dominant groups changed among them, but reptiles occupying the ecological niche of a small insect hunter did not always give up their positions without a fight. After the ice age and space disasters that marked the change of geological epochs, the number of small reptile species decreased markedly, but after the stabilization of habitat conditions, they regained their lost positions in the ecosystems of the Neocene. Many new species have appeared among them, and sometimes they are very bizarre.
Lizards of the genus Herbichthys (the name literally means “grass fish”) live in North Africa, in the zone of tall grass savannas. They got their name for the specific body shape: a narrow trunk, strongly laterally compressed, greatly facilitates the movement among the dense grasses. It seems that the lizard slithers among the grass like a fish in water. During its movement, the position of its legs is almost vertical: it makes it easier to walk and run among the thick and tall grass.
The most widely distributed striped “grass fish” is a fairly large species of its genus. The length of its body is about a meter, and the tail makes about half of the entire length of the reptile. A tall leathery ridge runs along the back and tail, supported by the upper spinous processes of the vertebrae. A short helmet-shaped crest grows on the lizard’s head, separated from the crest on its back by a neck contraction. The body coloration of the striped “grass fish” is camouflaging: it is yellowish, with frequent brown vertical strokes and some gray spots. The iris of the eye is of “marble” pattern, so the lizard’s eyes do not stand out much against the general background. The lower eyelid of this reptile’s eye is transparent. This is a kind of protective device: while moving in the thickets, it closes the eye and protects it from accidental pricks of grass stems.
Striped “grass fish” feeds mainly on insects, although sometimes it diversifies its diet with small terrestrial vertebrates – frogs and lizards, as well as small rodents. For its everyday life, each lizard occupies a certain territory, driving away weaker congeners from it from time to time. Each “grass fish” has a shelter in its territory – an expanded and rebuilt burrow, a tree trunk rotten through from the inside, or a crevice in the stones. Here the lizard spends the night and hides from enemies. But it shows the greatest activity in the hottest time of the day – when most of its furry and feathered predators are resting in the shade. At this time, “grass fishes” scurry in the thickets of graminoids, hunting beetles and grasshoppers, their main food items.
In lizards of both sexes, there is a gular sac on the throat, that is very stretchable on the cartilages of the hyoid bone: it is yellow with irregular red spots in males and white with small rounded orange spots in females. When the lizard is calm, it is pressed against the chest and is invisible when viewed from the side or from above. During their conflicts, lizards stand parallel to each other, rising on their paws, and begin to stretch their gular sacs, trying to appear as large and impressive as possible. This is usually enough to resolve minor conflicts outside of the courtship season. At this time, males and females live as if in a “parallel world”: the territories of lizards of different sexes completely overlap, and females conflict only with females, and males only with males.
But in the courtship season, the presence of a mate of the opposite sex at the territory becomes a clear advantage. Males begin a furious “revision” of the boundaries of their territories, trying to expand their “possessions” so that as many females as possible live on them. And here it is impossible to do with simple displays only: sometimes they turn into serious battles, and one of the rivals (or even both at once) gets numerous scars, fractured digits or even the lower jaw.
When a male sees a reptile of his own species approaching him, he first tries to identify its sex is it a female or another male. To do this, he turns with his head towards the intruder (this position downplays his apparent size in front of a possible female) and quickly opens and closes his gular sac several times, turning his head sideways. This is a standard signal for recognizing a relative, and it must mirror his actions. Depending on the color of the intruder’s gular sac, the male behaves differently.
If another male has invaded the territory of a male, the events can be very dramatic: both lizards prepare for battle. Before the fight, each male tries to demonstrate itself “in the best possible light”: he rises on his hind legs, holding on to the stems of herbs, hisses loudly and opens his gular sac. If this display does not help, and the male competitor does not leave the territory, then the conflict can result in a rather brutal fight. During the fight, the rivals grab and scratch each other with their paws, bite and wriggle with their whole body, trying to squeeze the opponent and force him to surrender. Usually a male who has admitted his defeat stops resisting and presses his paws to his sides. This action serves as a signal to appease aggression: the fight immediately stops, and the defeated one tries to quickly leave another male’s territory.
If the intruder is a female, then an experienced warrior turns into a gallant groom. After making sure by the smell that it is a female in front of him, the male begins courtship: he walks around the female on outstretched legs and from time to time opens his gular sac, visually exaggerating his own size. Stopping in front of the female, he shudders slightly with his whole body, after which he hisses loudly. At this time, his coloration changes: the disguise fades into the background, and broad brown transverse stripes appear on the body. At this moment, the general coloration of the body pales, becoming almost white. If the female is ready to mate, she lies down on the ground, slightly leaning sideways, and freezes. The male mates with her and the female leaves. Sometimes the male tries to hold her: he grabs her tail or the hind leg with his jaws. But usually he does not manage to repeat mating with the same female.
A month after mating, up to 10 eggs form in the female’s body. The female lays them in a secluded place: in a hole, in moist soil under a fallen tree, or at the river bank among vegetation. Egg laying repeats twice during the wet season, with a break of two to three months. This species does not care about offspring at all.
Incubation lasts about two months. Young lizards about 15 cm long hatch. Their backs lack yet a crest characteristic of adult reptiles, and their body has a cylindrical shape inherent in most lizards. But from about six months of age, the spinous processes of the vertebrae begin to grow, and young “grass fishes” get crests on their backs. At the age of two, young lizards become sexually mature. Their life expectancy can be up to 15-18 years.

Robber monitor lizard (Praedovaranus caninus)
Order: Squamates (Squamata), suborder Lizards (Lacertilia)
Family: Monitor lizards (Varanidae)
Habitat: savannas of North Africa, Atlas Mountains, also Southern Europe.
A hot climate represents not the most favorable conditions for mammals. But birds and reptiles are much more resistant to high temperatures than mammals. So, some of them have learned to take advantage of this feature in due course of evolution.
In areas of a hot climate, the number and diversity of all kinds of reptiles is much greater than of mammals. In the African savanna of the Neocene epoch, a reptile appeared, which substitutes mammals in the role of a medium-sized predator – it is a robber monitor lizard.
Robber monitor lizard is a large representative of its family. But it is rather slightly built, having a light build. The body length of this predatory lizard is up to 3 meters along with the tail, and its weight is about 30 kg. The animal looks like some prehistoric thecodonts: the legs are long, directed down and slightly to the sides.
The neck is flexible and relatively long. The head is large and compressed from the sides. Small corneous outgrowths stick out near the eyes on the bridge of the nose, being especially developed in males. The eyes are large; the vision is partly binocular. Teeth are sharp, blade-like and cutting.
The skin is yellowish in color with a dark pattern: brown spots on the head are small; spots on the trunk and tail become larger and merge into uneven transverse stripes.
Like all monitor lizards, this reptile is an active solitary predator. In the African savanna of the Neocene epoch, this monitor lizard is an analogue of jackals and other small predators. It hunts medium-sized animals, catches baby harelopes and giraffe ostrich chicks, eats lizards and snakes. The robber monitor lizard hunts most often during the daytime, when mammals rest in the shade. On occasion, it willingly eats carrion. The monitor lizard eats prey, holding and tearing it with its clawed front paws.
It is a solitary territorial species. The lizard does not mark the boundaries of its site in any way, but it remembers them well and guards jealously. Outside of the breeding season, each reptile is ready to attack a relative with all its ferocity, and to put it to flight by any means.
The courtship process of these monitor lizards turns into a demonstration of physical force: males walk next to each other, inflate their throats, hiss, show their teeth, make a lunge at the opponent. If these performances do not reveal the strongest one, a real battle begins. Males fight by standing on their hind legs and grappling each other like wrestlers. This is how their ancestors, the monitor lizards of Varanus genus, the only one in their family in the Holocene epoch, established the hierarchy. During the fight, opponents bite and scratch each other, so the “veteran” of many courtchip duels is literally riddled with scars. The winner of the curtship tournament chases the loser by biting his hind legs and the base of the tail, after which he returns to the female. To make a greater impression on the female, the male walks in front of her on two paws, shakes his head and whips his tail on the grass.
Like all types of monitor lizards, the robber monitor lizard is an oviparous reptile. The female lays up to 15 eggs at a time, burying them in a hole (usually on the river bank), and does not take care of them. Incubation lasts about 3 months. The just hatched cub differs from adult reptiles by a more saturated cross-striped coloring. Its length is about 20 cm along with the tail. It immediately leads the life of a predator, attacking large insects and small lizards, sometimes even those that exceed its size. Cannibalism is characteristic of this species at all stages of development. If an animal managed to survive the first two years of its life, it has the opportunity to live a life full of dangers lasting about 40 years.

Snouted cricket snake (Locusterpeton disproportionalis)
Order: Squamates (Squamata), suborder Snake (Serpentes)
Family: Broad-tailed snakes (Latiserpentidae)
Habitat: savannas of North Africa, the Middle East.
This one is a small snake representing a family that evolved in the Early Neocene epoch. This reptile species has adapted to feeding on insects, mainly orthopters (crickets, grasshoppers and locusts).
The body length of a cricket snake reaches 1 meter. This species is characterized by a specific body shape associated with behavioral and feeding mode features. The front half of the body, including the head, is very thin in this snake. The back half is noticeably wider and more massive. The tail is short and makes no more than 1/5 of the total length of the snake. The meaning of this shape is that the snake feeds by grabbing insects from the stems of plants. In this case, it can lift the front part of the body high, and the back serves as a reliable support for it.
The head is very small; the tip of the muzzle is stretched forward and covered with strongly keratinized skin. With the help of such a nose, the snake digs out egg pods of some orthopters in the sand, searching for them by smell. The eyes are relatively large; the mouth is wide. The teeth are pointed, piercing and bent back. Vision is sharp; there is an interesting feature of visual perception: like in frogs, vision is particularly sensitive to small moving objects.
The body has a camouflage pattern: longitudinal brown stripes on a greenish-yellow background. On the back of the body, the stripes turn into a random spotted pattern.
The cricket snake feeds mainly on large insects, grabbing them from the stems of grasses. Occasionally, in addition to insects, it eats small vertebrates. This reptile is remarkable in an exceptional keenness of touch sense: being unable to hear sounds, it can detect the presence of a chirping orthopter by vibrations that travel along the grass stalk on which the insect sits. This skill allows the cricket snake to hunt at night.
In case of danger, the snouted cricket snake most often uses a disguise: it freezes, doing a “tail stand” and swaying in time with the movements of the grass. It escapes only as a last resort.
During the mating season, males compete with each other, making a tailstand and pushing the opponents with their lower body parts. The male stays with the female for some time, driving away other males from her and mating repeatedly.
This species reproduces by laying eggs in the loose ground under bushes. There are up to 10-13 eggs in a clutch, and there are up to 3 clutches per year. Young snakes feed on termites and ants. They have a uniformly thickened body of a typical “serpentine” shape, keep near termite mounds and hide in rodent burrows. Sometimes they even dig their own burrows in the thickness of the underground nest of social insects. Switching to an adult diet, the growing animals change the proportions of their bodies and begin to live openly.
The life expectancy of this snake is short: up to 15 years.

Egg-eating drillsnake (Ovisugerpeton ovisugus)
Order: Squamates (Squamata), suborder Snakes (Serpentes)
Family: Toothbeak snakes (Odonatricidae)
Habitat: savannas of North Africa.

Picture by Arseny Zolotnikov

Most snakes are very similar to each other in their way of feeding: they hunt animals of various sizes (from snails or worms to crocodiles and antelopes), kill them by strangling, biting, or poisoning them with venom, and then swallow them whole. But among snakes, egg-eating snakes (the Dasypeltinae subfamily in the colubrid snake family Colubridae) stand somewhat apart in terms of feeding method. The diet of these peculiar snakes consists exclusively of bird eggs. Of course, on occasion, a large number of species of snakes eat bird eggs, but egg-eating snakes live only at the expense of this food type. They are able to swallow a whole bird’s egg, the diameter of which is several times the diameter of the body of the snake itself. The processes of the vertebrae, extending from above into the esophagus, serve as a kind of “saw” for opening the eggshell. The snake swallows the liquid contents of the egg, and spits out the shell.
In the Neocene, from some non-specialized colubrid snakes that lived in the savannahs, the another master of devouring bird eggs – the egg-eating drillsnake. This species is an ecological analogue of the modern egg snake, but it has developed a slightly different way of feeding, and its food object is remarkable by being a rare peculiarity.
This snake feeds mainly on the eggs of giraffe ostriches, the size of which, however, no longer allows them to be swallowed, as in the case of the egg-eating snake. Therefore, the egg-eating drillsnake has got a different kind of device for feeding on such eggs. The two pairs of front teeth in the upper jaw of this snake are greatly enlarged, flattened and directed forward. With their help, the snake drills a hole in the egg by rotating the head 180 degrees to both sides. In this regard, the skull of the drillsnake has also undergone changes. Since this snake feeds mainly on liquid food, there is no need to open its mouth much to swallow it. The bones of the skull of this snake have fused together quite strongly. The vertebrae in the front of the body of this reptile have also become more powerful, and their spinous processes are enlarged and expanded: strong muscles attach to them now. The egg-eating drillsnake spends a considerable part of its time underground, where it digs long burrows with its front teeth using similar circular movements of the head. In addition, this snake willingly uses rodent burrows for its life, further expanding and digging them. The teeth of this snake replace themselves as they wear out. This happens at a time when giraffe ostriches do not nest, and the feeding activity of the drillsnake is decreased. Due to the seasonality of the appearance of its main food, this snake is fully active only about two months a year – from the beginning of the nesting season of ostriches to the moment when embryos develop strongly enough in the eggs of the latest clutches. In the season of active feeding, the drillsnake quickly stocks fat and grows much faster than in the rest of the year.
The body length of the drillsnake is about two meters. Its skin color is dirty yellowish-brown with blurred “marble” splotches forming a cross-striped pattern; the belly is lighter, yellowish-white. The female of this species is somewhat more robust than the male, which is distinguished by a longer tail and brighter skin coloring.
This reptile feeds by getting close to the found nest from below from under the ground. In the search for nests, the snake is helped by finely developed senses of smell and touch. The snake feels the tremors of the soil produced by large birds, and by them determines the place where they stay for a long time – in this place the reptile is searching for their nest. Keen sense of smell allows it to accurately determine the shape of the nest by the smell of the droppings and the birds themselves. The sharpness of the snake’s sense of smell is truly fantastic: among the smell of droppings and the heavy specific “aroma” of the ostriches themselves, it can determine how intensely the egg “breathes” by touching egg shell with its tongue. If the intensity of the release of carbon dioxide is high, the snake refuses to attack: the embryo in the egg has already developed strongly, and the egg is unsuitable for nutrition. But if the egg has been laid recently, and especially if it is still covered with a thin layer of secretions of the bird’s oviduct, the snake begins feeding. Turning its head left and right, it drills the eggshell with its front teeth. At the same time, the reptile helps itself by regurgitating a little amount of gastric juice of a strong acid reaction, which additionally dissolves the shell. The scales on the body of the drillsnake have special protrusions: moving apart, they firmly hold the body in the hole during the “drilling” of the thick egg shell.
Having made a hole, the drillsnake turns the throat forward, through which it sucks the contents of the egg, greatly inflating the body in the middle part. After a hearty meal, the reptile crawls away and hides in a hole for a long time, digesting food. At this time, an active digestion process takes place, and the snake grows intensively. But towards the end of the nesting season in giraffe ostriches, the drillsnake slows down its growth and begins storing fat, which allows it to wait out a long starvation period without any problems.
The damage to the ostrich population from this snake is insignificant – during the nesting season of birds, these reptiles eat a maximum of 2-3 eggs in a clutch: the duration of the periods of digestion of food by these snakes affects it. But outside of the nesting season of giraffe ostriches, the snake does not always observe a strict “fast”. The drillsnake is sometimes able to attack small terrestrial animals: non-specialized teeth have also been preserved in the reptile’s mouth. This reptile is especially willing to ravage rodent burrows, eating their tender newborn cubs.
Also, outside of the breeding season of giraffe ostriches, the drillsnake willingly visits the riverbanks in search of eggs of turtles and lizards that are buried in loose wet sand. Having found the nest by smell, the snake sucks the contents of the eggs of the entire clutch one by one.
The egg-eating drillsnake uses its peculiar teeth not only for getting food, but also when defending against enemies, inflicting strong “pecking” blows – sharp attacks towards the aggressor.
The drillsnake does not always live underground: this reptile often crawls out to bask in the sun, and also searches for bird nests in low trees. Its eyesight is poorly developed: the drillsnake is short-sighted and does not distinguish colors. But a keen sense of smell allows it to easily find tasty prey.
The mating games of this reptile take place on the ground surface. Usually snakes of this species gather near stones heated by the sun. In the evening, when the nocturnal predators have not yet woken up, and the stones still keep the warmth of the sun, these snakes crawl on them and start tournament fights: males entwine with each other, roll on the stones and hiss loudly. Usually the defeated snake tries to leave the “tilt yard” as soon as possible, but if equal opponents meet each other in a fight, teeth can be used. Since the teeth in the back of the mouth are relatively weak, snakes can only inflict shallow wounds on each other.
The winner male tastes the scent of the females gathered on the “tilt yard” with his tongue, searching the one ready for mating among them. He starts chasing her, biting her sides with the edges of his jaws, crawls forward and blocks her path, forcing her to stop. Mating takes place in a shelter – between rocks or in a wide burrow. After it, the female bears eggs for about a month, and then lays them in a secluded place, usually in soft soil under large trees. Sometimes clutches of drillsnakes, numbering 15-20 eggs about 4 cm long covered with a leathery shell, can be found in deep hollows of trees or in rotten trunks lying on the ground.
Egg development lasts about six to seven weeks. Young snakes differ from adults by contrasting coloration – yellow with brown transverse stripes. They shed on the second day of life, and after that they begin to feed. Their food consists mainly of small animals (at night young snakes come out of their holes and search for snails, which are their favorite food), and also includes eggs of small birds nesting on the ground. The length of a newborn hatchling is about 20 cm, but it grows rapidly, reaching half a meter in length at the age of one year. In their youth, drill snakes spend most of their lives on the ground, hiding in burrows from enemies or waiting out the hottest time of the day there. So they do not compete with adult representatives of their species. But when it reaches about a meter and a half in length (in the third or fourth year of life), this snake can already attack the nests of giraffe ostriches and passes mainly to underground life. Sexual maturity in this species comes in the fifth year of life, and the general life expectancy is approximately 20 years.

This snake species was discovered by Arseny Zolotnikov, St. Petersburg.

River adder (Potamobitis planiceps)
Order: Squamates (Squamata), suborder Snakes (Serpentes)
Family: Vipers (Viperidae)
Habitat: rivers of North and West Africa (the Saharan Nile and its tributaries), lakes and swamps.
In the process of evolution, snakes repeatedly passed to aquatic lifestyle. In North Africa of the Neocene epoch, when the climate became more humid and the savannah was covered with a network of rivers and lakes, some snakes repeated this step once again: a representative of the viper family developed the aquatic habitat.
The river adder is an aquatic venomous snake up to 2 meters long (the female is larger than the male). It leads an almost completely aquatic lifestyle, and rarely gets out on land. But the skill of crawling on the ground is not completely lost, and during a drought this snake can easily crawl from one reservoir to another.
In the appearance of the river adder, many features that it shares with its ground-dwelling relatives have been preserved. It is characterized, for example, by a flat head with a pronounced neck tapering. The corners of the head are pulled into small skin blades – a kind of “stabilizers” that serve as depth rudders. On the back half of the body, a low skin ridge runs along the back, serving for swimming. The end of the tail is deep and compressed from the sides – it works as a tail fin. The body is relatively thick, which is typical for vipers. The belly scales became somewhat shorter than in terrestrial relatives, but did not disappear completely, as in Holocene sea snakes.
The nostrils are shifted to the tip of the muzzle and close with leathery caps. River adder can hold its breath for about an hour. The eyes are very small, located on the sides of the head. The eyesight of the river adder is rather weak: in the water muddy from algae, it can be completely useless. This reptile determines the presence of prey by smell (using its tongue) and by the movement of water: the edges of the lips are covered with cells sensitive to waves spreading in the water – this is a kind of analogue of the lateral line developed in fishes.
The body color is striated, silver-gray with green transverse stripes; the belly is greenish-white. There is a longitudinal dark stripe on the back, consisting of a series of contiguous rounded spots.
Like all snakes, the river adder is a predator. It feeds mainly on fish and giant neotenic tadpoles of the local trapmouth frog, but occasionally eats small birds appeared in the water and waterfowl chicks. It swims quickly, but reluctantly, and prefers to catch prey from ambush. Usually the snake disguises itself by burying itself in silt, or hides in the thickets of aquatic plants.
At the beginning of the rainy season, this snake begins mating games. Courtship of males can be very rough: several individuals gather in well-warmed shallow waters, and chase a swimming female in a pack. At the same time, they try to push each other away from her. The winner of this tournament holds the female by wrapping around her body.
The river adder is viviparous; once a year the female gives birth to up to 10 juveniles each about 25 cm long, completely ready for independent life. The young feed on tadpoles of small frogs and fish fry.

Thermovisor viper (Scannerpeton thermovisor)
Order: Squamates (Squamata), suborder Snakes (Serpentes)
Family: Vipers (Viperidae)
Habitat: savannas of North Africa.
During the change of the Holocene to the Neocene, a mass extinction of large animals happened. Their place was immediately taken by small and rapidly reproducing species. For some time (about several tens of thousands of years), there was a real “mouse kingdom” on Earth, when large species were extremely rare, and the number of small ones increased many times, and they dominated natural communities. In such conditions, species that feed on small animals have gained an advantage. Among them, there were various predatory mammals, birds and reptiles. Among reptiles, snakes gained a great advantage in the struggle for existence, because in due course of evolution they specialized in hunting small mammals and birds. When some rodent species have increased in size in the course of evolution, hunters for them have also become much larger.
A completely unique creature has appeared among African snakes – a large venomous snake species up to 3 meters long, belonging to the viperid family. This species is characterized by a special device for hunting warm-blooded prey: this snake can sense heat radiation. Such an idea is not new among snakes. In America, in the Holocene, a large number of rattlesnake species lived, known for their ability to distinguish the heat radiated by their prey, small rodents. But the African thermovisor viper is fundamentally different from American rattlesnakes by the features of thermosensitive organs: it literally sees heat by perceiving infrared radiation with the help of its eyes. This ability was noted for turtles, but in the Neocene it developed in this snake species independently of them. Heat represents long-wave electromagnetic radiation, and it took quite a few changes for the snake’s eyes to become sensitive to heat.
Externally, the thermovisor viper practically does not differ from other large vipers. The snake’s physique is heavy: its body is thick and the tail is short. The coloration of the scales is camouflaging. Its head is broad and flattened. There are two poisonous fangs in its upper jaw.
The food of this reptile species is made up of mammals and birds weighing up to 2 kilograms.
The thermovisor viper is rather sedentary. It spends a significant part of the day in shelters. In the savannas of Neocene Africa, a large number of large animals roam, as well as giant birds, giraffe ostriches. In such conditions, the animal risks being crushed by unsuspecting herbivores. To avoid this, the snake utters warning sounds: when a large animal approaches, it whistles loudly, forcefully blowing air out through loosely clenched jaws. Such a warning is enough to leave the reptile alone.
During the day, the thermovisor viper hides in a hole or in a dense bush and rests, and in the evening, when the air temperature drops and potential prey comes out to feed, the snake starts hunting. In the eyes of this snake, the world most likely looks quite strange and unusual for us. Against the background of the night savanna, the huge bodies of sleeping animals stand out clearly for the snake’s gaze. They are not interesting for the reptile: their body temperature is lower than that of suitable prey. But small warm (“bright” for snake’s eyes) creatures represent a suitable prey. This snake does not distinguish between real colors visible in daylight, but black-and-white and thermal vision is perfectly developed: the rods in the snake’s retina are very small, and this feature provides a large resolution of the eye.
Males of the thermovisor viper are slimmer and longer than females. During the mating season (spring and autumn), they arrange courtship tournaments, gathering in groups on the outcrops of rocks well warmed by the sun. Males arrange tournaments, standing on their tails and measuring their height.
Like all its relatives, the thermovisor viper is a viviparous species: twice a year every female brings up to five large juveniles about half a meter long. The young do not eat anything for the first few days of life, although they have poisonous teeth and are able to defend themselves immediately after birth. After the first skin shedding, young vipers begin to feed on rodents and chicks of ground-dwelling birds. Sexual maturity occurs at the age of 3 years with a length of up to 2 meters.