Forgotten Siberia Speculative Project

There are no vertebrates in Siberia of the Carboniferous and Permian periods, except for axolotl-like Discosauriscus and Temnospondyli. What if we just didn't find the inhabitants of these places?

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THE FIST ANGAROVENATOR - ALTERNATIVE REPTILE!

While teliphones are building calamite catacombs, few vertebrates have mastered the arid terrain. One of them was the first angarovenator - Lapideusunguis adam, the "stone nail", which occupied a niche similar to modern geckos.

Lapideusunguis is significantly smaller than Moropiton and, possibly, slightly larger than adult Ariekanerpeton individuals.

Clockwise from top to bottom: Moropiton moropiton ssp. pushkini, pearl mole spider, Lapideusunguis, Oxykoilia, Poseideongenia. In the background - Ichthyocetus megalos

The body is elongated, has a triangular shape in cross section due to the high raised ribs: the thickness from the head to the middle of the tail remains the same. The legs are longer than those of the ancestors, which allows you to travel long distances.

The fingertips are covered with a keratin cover, convergent to the fingertips of tree frogs: they protect the foot from hard and often very hot/cold soil and aggressive substances and allow effective digging.

One recent scientific paper (Evolutionary origin of Hoxc13-dependent skin appendages in amphibians - the pictures above are taken from there) suggests that the claws of amphibians and amniotes were not independently developed, as previously thought. This means that the common ancestor had keratinized fingertips like modern axolotls.

The skin is much thicker (especially the feet and eyelids) than that of the ancestors, but without scales: it hangs slightly at the edges of the trunk. The muzzle is pointed, the head is narrow; the parietal eye is developed, the pupils of ordinary eyes are vertical due to the need to hunt both in the morning sun and in almost complete darkness. The color is bright due to the absence of predators with developed eyesight and serves as a means of communication and recognition of each other at a distance.

Unlike sedentary discosaurids, lapideusunguis is a nomad. Although its anatomy does not allow it to move as fast as modern quadrupeds, this angarovenator constantly (once every two weeks) surveys its territory in search of arthropods. Usually the territory includes two or three calamite catacombs or the usual burrows of some Arachnetiflopontics - Lapideusunguis periodically hunts them, as well as spiders and insects, especially young individuals. His main time of activity is twilight, night and day, he waits in burrows dug by himself or abandoned phone burrows. In the evening, the angarovenator comes out before sunset and basks on the rocks; in the morning it warms up by contracting muscles like some modern pythons - another adaptation important for future evolution.

Another important difference from discosaurids is rapid maturation: instead of 20 years, the larvae mature in a few months. In general, reproduction for lapideusunguis as for amphibians in the desert is a hemorrhoid due to the need to search for a reservoir. Usually, adults are found near the catacombs at night, when rare rains fall. The female lays eggs on wet ground, the male fertilizes the eggs and the female swallows the future offspring like the recently extinct Rheobatrachus silus frogs, after which she drinks some water.

Famous Rheobatrachus silus photo

However, these seymouriamorphs have not yet developed this behavior to perfection, and therefore they usually search for the nearest large body of water, migrating to the remaining forest regions. During the mother's wanderings, the eggs manage to develop into larvae at the beginning or middle of metamorphosis. It is obvious that the following daughter species will abandon the habitat stage in lakes and puddles in favor of throat gestation.

The following posts will be about the development of offspring bearing in Sangaree and in general about the evolution of metamorphosis in amphibians. In them, I will slightly correct the description of Lapideusungis and maybe draw the behavior of this animal during the breeding season.

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Calamite catacombs of Central Asia

Hello! This specproject is back.

Today we talk about zombie forests - Calamite catacombs:

WHAT IS CALAMITE CATACOMBS?

Calamite catacombs is are imagined ecosystem of Early Permian (300-280 m.y.a), which are the remnants of forests of tree ferns and conifers in the rapidly growing desert. In fact, the calamite catacombs are the hollow trunks of giant ferns buried under a layer of silt and sand deposited from the bottom of lakes, as well as volcanic ash. These trunks connect the upper layers of salt marsh soil and deep-lying rock with the remnants of old forest soil above and limestone with karst caves below.

Fern Calamites and conifers Cordaites

HOW THEY FORMED?

As we said, these ecosystems are rapidly deserted territories, similar in formation to the Aral Desert. Before that, forests grew in this area, consisting of conifers with surface roots like modern spruce and tree ferns with deep rhizomes. Desertification salted the soil and removed moisture - because of this, ferns stopped reproducing, and their terrestrial shoots died. At the same time, conifers were better adapted to the new conditions, but the absence of a taproot meant death from lack of water. However, already at these times, various types of trees could be connected by roots, so far without the participation of fungal mycelium. In fact, this led to the emergence of hybrids - half-dead trunks of ferns buried under the ground fused with the root system of gymnosperms.

This is how the zombie forest was preserved in the desert.

Usually these fragments of the forest represented the shape of crescents, as they grew near rivers and lakes and often groundwater is preserved under their roots. Moreover, hollow calamite trunks and roots helped moisture penetrate deep into the ground and gradually wash out the rock, forming new underground reservoirs. Finally, burrowing teliphones, originally preserved thanks to tree trunks, created a system of caves between dead dry trunks of ferns, and early spiders fastened them with webs.

Speaking of teliphones...

WHO LIVE IN CATACOMBS?

Surprisingly, the prehistoric vinegar spiders of Central Asia and modern teliphones of the USA are commensurate both in lifestyle and size

With the loss of habitat in the form of forest litter and the arrival of a harsh desert climate, teliphones were forced to quickly adapt to new conditions. Fortunately, acetic arachnids had predadaptations to a nocturnal lifestyle and digging in loose soil (modern species can dig holes up to 1.5 meters!). On the other hand, some arthropods are forced to seek shelter, and some could risk waiting out the sun in the tunnels of teliphones. Soon these aliens accepted the spider tunnels as their home, safe from external influences.

For teliphones, such a neighborhood has become advantageous: instead of going to the surface to hunt, you can now endlessly explore your passages in search of prey. Moreover, the expansion of the moves meant an increase in hunting grounds for their owner. It is not surprising that the evolution of vinegar spiders has gone towards an underground digger like a mole.

The first forms of catacomb teliphones did not differ much from modern ones. In the picture attached to the post, we can see Arachnetiflopontica margaritari - a pearl mole spider. This species differs from its terrestrial counterparts only in its more powerful pedipalps, elongated tail thread and forelimbs, and a special, mother-of-pearl color. The latter is a neutral mutation caused by a decrease in the amount of pigment in chitin and its increased transparency: it is typical only for females. They build their catacombs in loose desert soil, and in rare cases they are able to dig a passage through plaster layers in the sand created during rare rains. Often the passages of mole spiders are populated by ordinary spiders: they strengthen the tunnels with their webs. Teliphones are usually tolerant of such co-authorship - so far, spiders are not yet able to use their silk to catch prey. Nevertheless, mole spiders try to hunt such neighbors, restraining their spread through the catacombs: untreated walls are often overgrown with fungi, which gives food to prey.

Gradually, competition in the thickness of the sand increases, which is why some of the teliphones through the trunks of the calamites are trying to arrange lairs deeper and deeper into the ground. Eventually, these miners stumble upon the parent rock from the marine sediments. Here, the evolution of teliphones takes an unexpected turn: instead of developing stronger pedipalps, vinegar spiders acquire a flatter, flexible and elongated body shape, small limbs that make it possible to walk both forward and backward equally effectively, developed vinegar glands previously used to protect themselves from other animals. Often, the tail thread of such forms thickened and acquired outgrowths, becoming like a hard, thick corolla. An example of this form is Oxycoilia pachiapinelo whose name literally means "Acid belly with a tassel". This structure is easily explained by a simple chemical reaction: limestone, reacting with acetic acid, breaks down into acetate, water and carbon dioxide. Oxycoilia use this reaction to build their catacombs: they release an acetic aerosol onto the wall, rub it with a tail thread, after which they dig the softened rock with either their limbs or a thread. They rarely do this, preferring to use the moves created before them, as well as the trunks of the calamites. Often these acidic teliphones rise into the upper layers of the ground for hunting, after which they take the prey for storage in special chambers: their catacombs serve more as shelters from their fellow moles than as hunting sites. Oxycoilia also accumulate oxygen in the upper layers of the soil - there is incredibly little oxygen in their passage.

Let's say a few words about reproduction in the end. Vinegar underground spiders live long enough - up to 8 years. Like modern species, these spiders tend to take care of their offspring. During the breeding season, young male mole spiders go beyond the tunnels to go a long way in search of unfamiliar catacombs: at this time they lead the lifestyle of ordinary teliphones. Finally, they find tunnels of an alien population, where they mate with females without any problems. Some continue their journey, while the rest remain in the found catacombs.

And while the spiders are building their burrows, the trees will finally disappear due to old age: the terrestrial part of the catacombs will not live more than a millennium. However, underground, a network of burrows and trunks will create a universal bunker for any life hiding from the sun. One of them is the unusual sisters of modern amniotes who refused to invent the egg...

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Advanced Ichthyocetus - Batrachorusalkas

Usually, the rate of evolution of secondary aquatic animals is high - for example, in whales, the transition from semi-terrestrial to semi-aquatic animals took no more than 8 million years. In ichthyosaurs, this interval is reduced to 4-5 million years (from 250 to 246 million years), in mosasaurs it increases to 39-18 million years (from 125, counting from the species Kaganaias or 99, counting from the species Aigialosaurus to 86 million years ago). One can also recall seals (26 million years), metriorhynchidae (3 million years), plesiosaurs (6 million years)*... This is enough time to transform the limbs into fins and become adapted to life in the open seas.

Whale evolution. Author unknown, found in internet.

The situation becomes strange when looking at ichthyocetus, which initially retained many features for life in water and almost never went on land. The ancestor of the clade, tulerpeton, lived in the Ural Sea 365 million years ago: however, 58 million years later (!) we see quite primitive species that differ from their ancestors only in increased size and a narrower skull (as well as a specialized tail). Obviously, in addition to such forms, we must inevitably find more advanced species capable of permanent life in open waters.

Ichthyocetes - late primitive species of Ichthyocetesidae (we will use there terms as synonyms, meaning whole clade, not concrete species).

Before we proceed to their discussion, let's clarify the features of ichthyocetus. These animals are ideally adapted for shallow waters, characterized by developed limbs for movement in difficult coastal environments and a movable neck. We should immediately note that this fact makes this clade dependent on glaciation cycles, therefore, transgression and regression of the seas. As a relative of tulerpeton, ichthyostega, ichthyocetus moved on land (if the situation forced them) like seals, stretching their body with their forelimbs (while the body could not bend similarly to modern lizards or salamanders). Thus, ichthyocetes, when moving in water and land, more often use their tail and limbs, especially the front ones, while the body itself is motionless. The neck is mobile, but limited in length and mobility due to its primitiveness.

It is quite obvious to see a tendency in ichthyocetes to decrease body length and tail/fin development. Nevertheless, in all ichthyocetes, the forelimbs never became fins completely, but on the contrary, developed mobility and flexibility for - oddly enough - capturing prey. This fact is explained by the limited mobility of the skull and the diet of ichthyocetes - the search for benthos/armored mollusks. The "hands" allowed them to capture prey, while the powerful jaws crushed the shells. However, the limbs themselves are flattened due to soft tissues, and the fingers are connected by webbing. This allows them to actively use it in swimming, especially if they need to quickly get up for a new breath of air. In other cases, the tail is used for movement.

Tulerpeton and Ichthyostega found fossils

As a result of these adaptations, the most progressive group of ichthyocetes from the Early Carboniferous appears - Batrachorusalka (mermaid frogs). This group is a medium-sized nautiloid and ammonite hunter. They appear after the Serpukhov extinction, as shallow waters lost most of their species and became less productive due to a decrease in carbonate platforms (shallow waters built by reefs) and, consequently, a slowdown in speciation of species. Nevertheless, it was during this period that ammonites and natuiloids reached their heyday, and some representatives of ichthyocetes began to specialize in them, becoming batrachorusalkas. The remaining species of the clade under consideration remained in shallow waters, almost ceasing to evolve, as well as gradually reducing their range: the only thing that led to the emergence of new species was a drop in sea level and fragmentation of the original populations into smaller isolated groups.

Batrachorusalkas have reduced hind limbs, a short barrel-shaped body and a long tail convergent to those of ichthyosaurs and mosasaurs. When moving, the forelimbs stabilize the body, as well as a small "dorsal fin". The developed "hands" are capable of folding into a compact fin and are usually placed to the sides. When chasing prey, batrachorusalkas captures prey with its jaws after a high-speed pursuit, after which it stretches its "arms" forward and captures the shell of the nautiloid, after which this ichthyocetes goes into depth to dismember prey. This is done as follows: the animal crushes a part of the shell to deprive the mollusk of the opportunity to hide in its house, after which it grabs the flesh of the prey with its teeth and pulls the nautiloid's body with its forelimbs from the head, lifting them up. Then the batrachorusalka swallows the part of the prey caught in its jaws, shaking its head, and the process repeats. Since farmhands can hold air for up to an hour, they can take their time in eating food.

Batrachorusalkas have two types of teeth. The teeth on the palate and lower jaw are flat, oppressive, and concentrated in the back of the jaws. The extreme dentition, on the contrary, is cutting, convergent to the teeth of Eugeneodonts with symmetrical teeth. Another feature of the species is the nostrils, which retain their position at the tip of the muzzle: these animals have a habit of floating vertically, "like a soldier".

The decline of batrachorusalkas, which could reach a size of about 4 meters, occurred with the appearance of large eugeniodonts in the region, which surpassed marine tetrapods in speed and agility, and also hunted the same ammonoids and nautiloids better. Moreover, the edestus of the Ural Sea easily took away the caught prey from the farmhands, since the latter ate their prey too slowly. Meanwhile, the more primitive shallow-water batrachorusalkas suffered from habitat loss and competition with their more basal relatives. 310 million years ago, the last mermaid frogs became extinct. The remaining ichthyocetes die out at the end of the Carboniferous due to changes in the hydrochemistry of the coasts caused by the extinction of carboniferous forests, although some representatives (descendants of batrachorusalkas, who began to live on the northern side of the Ural Ocean and became inhabitants of mossy reefs) live to the end of the Asselian Permian, having experienced a short-term surge in speciation 294-292 million years ago due to the largest transgression of the sea in the Permian (regression finally destroys the last ichthyocetes).

So the unique amphibian dynasty and the last of the Stegocephals (Stegocephali, which does not include the ancestors of modern tetrapods) ceased to exist.

NOTES (*) The calculations are approximate and made by the author of the article. The author looked for basal representatives of the family with legs and without legs, after which he calculated the gap between these forms. They are accurate enough to give general ideas on the topic under discussion, but nothing more.

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Amphibian Perucetus and giant scissor sharks

In previous posts, we considered Moropiton and Poseideongenia, two groups of animals that migrated to Siberia through the Ural Sea in the Late Carboniferous. Before moving on to the actual descendants of these Seymouries - the Angarians themselves - we can distract ourselves with the creatures that the Moscow settlers could encounter on a vegetable raft.

The Dynasty of marine amphibians

Let's start with a strange speculative kind that shouldn't exist. Ichthyocetus, the "whale fish", is a large animal reaching a size of up to 2.5 meters and is a direct descendant of tetrapods of the Moscow Sea, primarily tulerpeton. The latter is known primarily for its six-toed limbs developed relative to other modern tetropods, as well as for its location. The fact is that the remains of the tulerpiton were located 200 kilometers from the supposed shore: this and the very structure of the body of the tetrapod under discussion suggest that the animal lived in shallow water, breathing atmospheric air (no bones corresponding to the gills were found, and the head was separated from the body - i.e. the tulerpeton could lift its head) and moving forward using the legs, pushing them off the bottom (their strength would not be enough to allow the toolerpeton to move on land). It is possible that some tetrapods could have stayed in this habitat, becoming the main predators of shallow waters, where larger predators like eugeneodonts or placoderms could not move normally.

Tulerpeton, 360 m.y.a. Art by Dmitry Bogdanov

Tulerpeton found fossils

Ichthyocetus is the last representative of this hypothetical clade, whose population was almost completely destroyed by the decline in sea level due to the new peak of the Karoo ice Age. His basic diet is benthos, which he can find in the buried ground: echinoderms, starfish and lilies, as well as, if luck smiles, the corpses of marine animals that the surf brings. He could also purposefully hunt for moropitons if they swam too deep. The bones of ichthyocetus are incredibly dense; this allows it to stay in the water during strong waves. This animal is able to sense the approach of a storm - then it tries to find the shore and crawl out onto it, burrowing into the sand; then they are most vulnerable. If it is impossible to find the shore, then the ichthyocetuses go to depth, swallowing air, where they can stay for 3-4 hours. Sometimes this tetropods go deep in search of new food sources, where they can catch young eugeneodonts or small fish. Surprisingly, ichthyocetuses are not the largest representatives of their clade (let's call it Ichthyocetusae): some species could grow up to 3 meters and lead a more pelagic lifestyle.

They usually appeared during periods of intense glaciation with a reduction in their original habitat. Unfortunately, this time climate change has become insurmountable.

Something about scissor sharks

If the meeting of protoseimurians with their "cousin" was unreliable, then the same cannot be said about eugeneodonts. The largest animals of the sea were the edestus, or protopirates. Although the largest protopirate species, E. vorax, could reach 6 meters (making it the largest predator of its time), the Moscow species were somewhat smaller and reached a maximum of 4 meters. These sizes correspond to the modern white shark and mako shark.

Edestus, 313—307  m.y.a. Art by Dmitry Bogdanov

Comparison of the four species of Edestus. Authors of this illustration is Leif Tapanila and Jesse Pruitt

Both poseideonogenes and moropitons encountered these cartilaginous fish - most likely, they were four-meter E. heinrichi and E. triserratus commensurate with ichthyocetus. Most likely, the edestus hunted numerous nautiloids and other soft-bodied prey and could well attack rafts, mistaking them for a dead cephalopod with a spiral shell. The protoseimuria themselves would not be of interest to the edestus - they are too small. That's what saved them.

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Moropiton,

"baby pythons"

Europe and Western Russia, 310-305 m.y.a.

Moropitons, "baby pythons" are primitive Discosauriscidae that spread across Europe shortly before the late carboniferous collapse of tropical forests: this event led to the splitting of moropitons into many new species that inhabited the entire Northern Pangaea and Angara - but the main separation occurred about 306 million years ago due to differences in northern and southern ecosystems. We are talking about two subspecies of moropitons - Pushkin's Moropiton and Dumas' Moropiton.

The southern moropiton, or moropiton Dumas, inhabits the territories of the Czech Republic, France, Germany and other countries of Central and Eastern Europe, preferring the shores of reservoirs. Living under the pressure of large predators, he often burrows into the mud, preferring twilight spearfishing with the help of electroreceptors. Despite this, Dumas' skin is relatively dry, and an adult animal can travel long distances to find the best spawning ground. The size of this subspecies does not exceed 40 cm in adults, but they are rare - Dumas clearly shows neotenia, which eliminates competition with commensurate amniotes. A striking feature of moropitons is their venom, and Dumas best corresponds to it, since this subspecies is convergent to Bombinatoridae*. At the sight of danger, Dumas turns over on his back, showing a striped red-black belly and a bright blue mouth.

Unlike southern moropitons, Pushkin's moropiton grow up to 60 cm and almost do not turn to neoteny. This subspecies appeared later than Dumas, formed during the degradation of the Moscow carboniferous forests 310-308 million years ago: it is adapted to life in dry conditions. They begin their journey in forest reservoirs, where they develop as larvae for 20 years; after that, adults leave for more arid regions. The northern moropiton is less poisonous than the southern one - there are almost no predators in the Moscow forests that could pose a danger, while the habitat conditions are much worse than in European forests. The skin is dry and much better able to tolerate lack of moisture than Dumas; nevertheless, the amphibious nature forces Pushkin to stay close to water sources and in deep burrows/crevices. Pushkin's coloring is faded, reminiscent of that of a Blue-tongued skink the blue mouth remained as a way of communicating with relatives and scaring off predators. Moropitons feed near the seashore, eating up discarded corpses of marine life, and also do not disdain cannibalism and insect hunting.

307 million years ago, forests in Moscow disappeared, and the northern subspecies became extinct; however, part of the population got to Angraida with the help of plant rafts. The southern subspecies dies out later due to competition with its descendants.

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Poseideongenia,

"Mother of the Month of Poseidon"

Europe, 320 m.y.a.

Ancestor of Seymouriamorphs, direct descendant of the Siberian Poseideongenia - Utegenia.

Omnivorous terrestrial predator, gravitating towards reservoirs. The skull does't exceed 10 cm in length. On the "reconstruction" of the animal, you can see blue bags similar to the cheeks of a tegy lizard: they are a tool for solving territorial issues and finding a partner - Poseidonogenians do not have good hearing or sense of smell and therefore orient themselves to developed, albeit partially myopic color vision. Osteoderms of the back and abdomen are hidden under the skin due to uselessness - there are no predators in Moscow that could pose a danger to the species. This is also the reason for the great fearlessness and curiosity of individuals.

In larvae, osteoderms are also developed, but hidden under thick skin and serve as protection from their parents. Also lavrvae have fins instead normal limbs as arhaic feature.

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WHAT IS FORGOTTEN SIBERIA?

If we try to describe the essence of Forgotten Siberia, then this is a speculative project about... parareptilia. Hmm, perhaps you remember the same spec from Kozman, the author of "All Tommorows"? We took same idea, but whith 🤓 energy - basically decided to make it as realistic and able to fit into our reality as our data allows.

In shot, a primitive seymouria-like creatures traveled on Sibiria continent and slowly move in taiga-like north forests, were started evolving in some bizarre forms called Angarovenators before Siberian traps caused the Great Persian Extinction and burn almost all angarovenators bones.

Kosmen's parareptilias

P.S. Some paleontologists, like Mikhail Ivakhnenko, include Seymouriamorphs in Parareptilia, but modern science considers they to be Reptiliomorpha.

Too complicated? Let's try to explain below.

Spec himself grew out of a little-known fact. In the distant past, before the beginning of the Triassic period, China, Kazakhstan, Uzbekistan and Tajikistan, as Laurussia well as the eastern part of Russia — Siberia, were not part of Pangea, but formed 2 separate continents — Katasia (China) and Siberia (the rest of the countries). The last continent is called Angraida in Russian, after one of the largest rivers in North Asia. At first, these continents were separated from the rest of the land by the Ural Ocean, then by the Ural Mountains and the new sea, then comparable to the Himalayas, when formally this territory collided with Laurussia, the northern part of Pangea. It was in this area that the Siberian traps spread, destroying 90% of the species on Earth and causing the Great Extinction of the Persians.

Earth 340 million years ago. Yellow land - continent Sibiria or Angarida (not misunderstood whith modern region). Relative to the current position of Asia, this continent is rotated 90 degrees counterclockwise, so Magadan was at the north pole. Angarida include Eastern Siberia, Kazakhstan, Uzbekistan and Tajikistan. Red land is Cathaysia - modern China.

And now the main nuance: in Siberia (starting from the eastern slope of the Urals), almost no vertebrate fossils dating back to the Carboniferous or Permian period have been found. The exceptions are the branchiosaurid Tungussogyrinus (Sibiria), who lived 250 million years ago, as well as the reptiliomorphs (Discosauriscinae) who lived 300 million years ago: Ariekanerpeton (Tajikistan, possibly Uzbekistan), Utegenia (Kazakhstan, China) and to a lesser extent Gnorhinosuchus (Kazakhstan). At the same time, an extensive fauna of synapsids, amphibians and reptiles was discovered in China and in the western foothills of the Urals. This means that the species quietly migrated to these continents, but did not inhabit Siberia.

Utegenia. Literally all terrestrial vertebrate from Angarida resembled axolotls. Also the Ariekanerpeton's larvae even had flippers that became limbs after metamorphosis. Interestingly, no fully grown individuals have been found in this species.

So, why Sibiria is empty?

First, it is worth remembering that relatively many insects, brachiopodas and other invertebrates lived in Siberia. Despite the lack of competitors, they did not grow as big as Arthropleura or Meganeura. Soon you will be able to guess for yourself why.

Secondly, it was a unique environment. Siberia was filled with a special, endemic ecosystem - humid Cordaites, taiga and even tundra. Yes, you heard right: in the Carboniferous and even the Permian period there was the Karoo ice age, which led to the formation of a temperate and Arctic climate. So maybe it was too cold?

Maybe. However, some African dicynodonts (they also found on the western slope of the Urals) lived in approximately temperate climates. Also, no one cancels the possibility of the existence of small reptilian and amphibian forms capable of hibernation, like modern live-bearing lizards and Siberian salamander.

Siberian salamander. and her habitat. The species is known for surviving deep freezes (as low as −45 °C)

Our spec explores the strangest explanation: the territory was early (320-310 millions years ago) occupied by poorly preserved forms who not displaced by more advanced amniotes due to their high adaptability to cold temperatures. Perhaps their skeleton was not completely calcified, and they were rare, which prevented them from being preserved in the geological history of the Earth. Moreover, a unperfect paleontological study of Siberia could also play into the absence of fossils of Siberian tetrapods.

Ariekanerpeton, Gnorhinosuchus (subfamily Discosauriscinae) and Utegenia (family Kotlassioidea) turn out to be the best candidates, since they were the first to settle on the continent at all. Considering that Ariekanerpeton and Gnorhinosuchus are much closer to the European Discosauriscus of the same time than Utegenia, the migration of seymuriamorphs occurred at least twice; moreover, these species could well be the ancestors of the Kotlassia, Microphon and Karpinskiosaurus found in the Urals, respectively. Speck suggests that the descendants of Utegenia remained in warmer regions, while the more land-based Ariekanerpeton split into southern and northern branches. The latter gave rise to the Angarovenator clade - small and medium-sized amphibians animals, more adapted to the dry land rather the rivers and lakes shores. Technically, this group would become convergent to the real Seymourias.

Kotlassia and Karpinskiosaurus, 265-252 millions years ago. Found in same place as Inostrancevia

Below is the first sketch diagram of Seymouriamorphas evolution, where the length of each rectangle corresponds to the life span of the species:

So, some fist speculated species:

Poseideongenia, "Mother of the Month of Poseidon". Ancestor of Seymouriamorphs from all Laurussia, 320-310 millions years ago. Omnivorous terrestrial predator, gravitating towards reservoirs. The skull is approximately commensurate with Seymuria and does not exceed 10 cm in length. The vertebrae are not fully fused and resemble those of embelomers: the body is squat and elongated, the head is quite large. It has osteoderms on its belly. Fist who migrated in Siberia. The process was similar to the migration sof Monkeys to South America on wood rafts, with the only difference that Poseideongenia can stop eating for month like modern amphibians and reptiles. A direct descendant of the Siberian Poseideongenia - Utegenia. Unlike the offspring, the species larvae also have fins instead of limbs.

Moropeton, "Baby snake": ancestor of Discosauriscus from Moscow forests, 310-305 millions years ago. The collapse of forests in the Carboniferous divided the European population of Poseideongenia into several parts, one of which became. This population also began to crumble, and it was the inhabitants of the Moscow forests who were able to cross the Ural Ocean again, but in Siberia they faced the future Utegenias. Some species remained in the south, gradually losing competition to their relatives (Ariekanerpeton, Karpinskiosaurus), adapting more and more to an aquatic lifestyle: but the rest went north. The vertebrae are not fully fused and resemble those of embelomers: the body is squat and elongated, the head is quite large. The skull is slightly less than 8 cm. Osteoderms are found only in larvae.

Erimopeton, "Desert snake": ancestor of the Angarovenators, an animal with a shortened life cycle and adaptation to deserts (300-280 millions years ago). Perhaps (it has not yet been clarified) the southern territories and the taiga of Siberia could be separated by a desert area and mountains - another barrier for animals, so that Angarovenators are divided into mountain and desert species. The size of the skull is about 5 cm. Desert forms have a special wrinkled skin, dry and covered with a lot of keratin plaques, which they shed. Wrinkles are designed to preserve and collect moisture from the desert air. They lay caviar during the rainy seasons or migrating to wetter mountains, where the larvae undergo an accelerated development cycle (a week versus 20 years in Ariekanerpeton). Later species evolved from this clade. Some species, on the contrary, rely on desert rains and eventually became completely neotenic one-day forms.

Pustulasuchus?, "bubbleskin crocodiles": Descendants of late desert forms that developed a special bubbly skin. Keratin shields have become scales, under which bubbles are formed that can be filled with either water or carbon dioxide (taken from the blood). These bubbles can work both as a hydraulic muscle that lifts scales, and as a cooling or heat-trapping surface. These species are medium-sized predators that inhabit the northern forests of Siberia.

Pennasuchus?, "feathered crocodiles": It's a crazy idea that Angarovenators create their own analogue of a feather and archive new ability - gliding flight. This idea is taken from Spec's early ideas and we are not sure if it will be possible.

So far, this is all that is on the list. New issues will be released soon that will more accurately consider the evolution of Hangar Generators and their neighbors. And before we say goodbye, we'll give you some early spec concepts…

OLD CONCEPTS

Old concept of Pustulasuchus. Initially, the ancient diapsids were considered the ancestors, but this idea has become too far-fetched

Discarded evolution of Angarovenator skulls as eureptilians. In this version, the Angaroventors, independently of other treasures, had temporal windows for 15 million years due to acidic upper marshes and demineralization of the skeleton. However, it turned out that the forests of Angarida were not so deficient in minerals

Papiasaurus, duck-like lisard is the penosuchus occupying the niche of a platypus. Most likely, the seymouries retained electroreceptors.

Pustulasuchus and Pennasuchus Kikimosaurus. These concepts were created before the Seymouriamorphas idea, so drawings are not relevant.

Pennasuchus Kikimosaurus and primitive Pennasuchus species. These concepts were created before the Seymouriamorphas idea, so drawings are not relevant. There also used to be the idea that Angarovenators are the ancestors of Longisquama, which explains the presence of dorsal feathers in these versions.

The article was created with the help of a translator. If English is bad, I'm sorry. If you have a VK account and speak Russian, then you can get acquainted with the project here.

The project has been created by ANIMARAPTOR.