Modern Anisospondyls can be placed into one of three major categories. There are the Brachiostomata, a group which was apparently very diverse in Eryobis' her past but is now only represented by a handful of species. There are the Trapezostomata, the Anisospondyls that evolved an enlarged bone below their jaws that effectively acts as a table to keep food from falling out of their mouths.
And then there are the Cryptognatha, the Anisospondyls that evolved a second set of jaws derived from their palate- and tongue bones and the group that by far the most modern Anispondyls fall into.
Cryptognaths as a clade are quite old and fossils like those from the Frouren Formation show that they were already around by the middle of the Bobossic period 145 million years ago. Curiously enough, this actually makes Cryptognaths the youngest clade among the surviving Anisospondyls, as Trapezostomes are estimated to have evolved over 12 million years before the first Cryptognaths appeared.
Yet despite-, or perhaps because of their later appearance on the world's stage, Cryptognaths are the most successful, numerous and diverse terrestrial vertebrates Eryobis has ever seen. One major reason for this is the fact that genetic evidence points to at least 4 different lineages of Cryptognaths surviving through the devastating cataclysm known as the World Scarring, making them the effective inheritors of Eryobis.
When biologists first touched down on Eryobis, they classified the Cryptognath Anisospondyls in 2 major groups: The Paleodactylae and the Symmetrodactylae. As the name may infer, this distinction was made based on the anatomy of their feet. Specifically, the amount of digits on the front limbs.
Cryptognaths are no exception. Biologists quickly noticed that that certain Cryptognaths had asymmetrical toes and this, combined with the knowledge that this asymmetry is a primitive trait, led to these Cryptognaths being labeled as "Paleodactyls". While this term has partially held up, its counter part, the term "Symmetrodactyls", has not.
Symmetrodactyls were grouped based on the fact that the toes on the lacrimal and neural limbs were equal in number and thus symmetrical.
Although the digits of Eusymmetrodactyls and Parasymmetrodactyls may look superficially similar, having a standard number of three digits on all front limbs, the differences in structure between the two groups already starts shortly after conception. Where Eusymmetrodactyls lost the fourth digit on their lacrimal limbs, the Parasymmetrodactyls lost their first digit to achieve digit symmetry. So while leaving similarly looking footprints, genetic testing found that Parasymmetrodactyls are actually more closely related to the Effingodactyls than to the Eusymmetrodactyls.
Yet, their relation to Effingodactyls is not a close one, having split well before the World Scarring event occurred. As such, Parasymmetrodactyls are a very diverse clade.
There are a number of physical traits that nearly all Parasymmetrodactyls share such as a scale covered hide, ectothermy and an olfactory organ located above the visendal mouth corner. This organ is often accompanied by a bony growth or spike and likely evolved from a taste organ that migrated outside the mouth to act as a nostril, as the Parasymmetrodactyls lost their true, fish-like ancestral nostrils.
The most basal members of Parasymmetrodactylae are the Siludrilidae, a family of serpentine Anisospondyls native solely to Hatèmica. Not much is known about these creatures as they all appear to be either fossorial, aqautic or a combination of both. From the specimens we have recorded and studied, we've found out that Siludrilids have very small, almost rudimentary eyes and instead rely on a pair of barbels on their mandibles to sense their surroundings.
Genetic evidense suggests that Siludrilids are the sister group to all other living Parasymmetrodactyls, which are classified as the Xenosauropsia. This group in turn seems to be into two major branches which likely diverged in the Recrescian stage of the Anaktisian period around 100 million years ago.
First of these branches is known as the Novocordea. What marks this group is the anatomy of their hearts and the fact that they do not seem to be completely ectothermic, with one family, the fully aquatic Sirenosauridae, being in fact homeothermic animals. These often marine animals are mostly herbivores that stay close to coastlines around Eryobis that will feed on seaweeds, though many supplement their diet with invertebrates and some are fully durophagous with a diet consisting largely of pectinauts.
Vyarisauria
Like the Sirenosaurids, many other Novocordeans seem to be aquatically inclined. The Vyarisauria are a clade consisting of several families of Xenosauropsians that are hypothesised to have originated on the shores of the Vyaris Ocean when it was forming as the paleocontinent Kwispuul broke apart. The least aquatic Vyarisaurs are the members of the Tarandrosauridae. The species in this family are often iguana like animals and are often omnivorous or herbivorous. The most striking characteristic of this family is that most males grow large horn- and antler like structures from their mandibles. These structures can actively impede their ability to feed, so it is likely that females use them to judge the fitness of males. In addition, some species have been recorded using these stuctures for both intraspecific combat and defense.
The great majority of crocodilian resembling Anisospondyls belong to the aptly named family Eryosuchidae. Much like terran crocodiles, these Vyarisaurs are often semiaquatic, armour plated carnivores. Eryosuchids can be found in tropical and subtropical regions all around the world where they prey on a wide variety of animals ranging from small fish to large game. While all Eryosuchids can swim, the degree to which they do this can vary quite a lot per species and region, as some Erysuchids will spend almost their entire lives living on land.
Another family of semiaquatic Vyarisaurs isthe Phocasauridae. These creatures can also be found all around the world, but unlike Eryosuchids have an elevated metabolism and higher body temperate that allows them to venture into temperate water as well. Much like the animals they derive their name from, the pinnipeds of old Earth, Phocasaurs can often be seen resting, alone or in colonies, on beaches and rocky outcrops in the sea. Phocasaurs can be extremely large animals, with the largest species reaching over 8 meters in length, though their long and muscular tail does take up half that length. As such, the diets of Phocasaurs can also differ quite a bit per species. Some are small fish specialists, sporting rows of jagged interlocking teeth that form a cage no fish can escape from. Others are large prey specialists, feeding on other marine Anisospondyls like aquatic Stauropterygians and Chalacheiropterans or even other Phocasaurs and then others are durophages or specialise in soft bodied invertebrates.
Cynerpetoidea
Curiously, despite being the most aquatic of the Novocordeans, the Sirenosaurids are not that closely related to the Vyarisaurs. Instead these marine grazers appear to be at or near the base of a superfamily known as the Cynerpetoidea. Unlike their closest living relatives, all members of this superfamily are mostly terrestrial. While bearing a vague resemblance to ancient land crocodilians of Earth, the Cynerpetoids are not Eryosuchids, with the similarities in appearance, most notably the rows of osteoderms and large scales likely being the result of convergent evolution.
The smallest and most widespread Cynerpetoids are the members of the family Suchocyonidae. These animals tend to be on the smaller side compared to some of their relatives, usually not exceeding 50 kilograms in weight. They are more omnivorous and often live in burrows. While they likely originated in Bloëcan Miesjeta like the other members of their superfamily, the Suchocyonids somehow crossed the Vyaris Ocean around 10 million years ago, likely rafting from Azchèda to Hatèmica and Lachoba. How they did this remains somewhat of a mystery, though one theory is that Suchocyonids have a higher salt tolerance than Cynerpetoids.
The Cynerpetidae on other hand, have always remained in Miesjeta. Among their relatives, it is the Cynerpetids with the highest metabolisms, which is perhaps why they of their relatives are most common in the older regions of the continent such as Azchèda and Lotharca. These creatures are fast animals that often hunt by chasing their prey down over a short distance. They also appear to among the most intelligent Xenosauropids besides Phocasaurs and Sirenosaurs and it is Cynerpetids that have been domesticated by the Eryobian natives in some regions.
The Cipehyolidae family contains some of the largest land carnivores alive on Eryobis. These carnivores are often the apex predators in the regions where they live, with especially the tropical and subtropical forest and wetland regions of Bloëca falling under their domain. Some biologists have compared Cipehyolids to ancient terran carnivores like Rauisuchians and Sebecids for these creatures also resemble land crocodiles. The biggest Cipehyolids of tropical Bloëca have been rumoured to stand up to 2 meters tall at the hip and measure over 10 meters from head to tail, which would indeed make them among the largest land predators of Eryobis and also some of the biggest terrestrial carnivores Humanity has ever encountered.
Eucryocardia
The second large branch of the Xenosauropsia is the one leading up to the Eucryocardia. As the name might suggest, all members of this clade are entirely ectothermic, which recent studies have shown might actually be a derived trait rather than the ancestral condition. The majority of modern Parasymmetrodactyls are Eucryocardians, with a majority of the latter belonging to the Eryolacertilia. Despite having been determinded to be the sister group to all other Eucryocardians and thus being the most basal, Eryolacertilians can be found on every continent except Rubiëra and fill most of the niches we'd associate with lizards on Earth and other colonies. They are a very diverse group and most are quite small, with only a handful surpassing 1 meter in length.
Plicataventria
Some of the strangest animals on Eryobis, which is saying something, are members of the group called Plicataventria.
At the base of this group are two families of aberrant creatues that vaguely remind of tortoises. The Irrisiidae, a family native soley to Hatèmica, are the most basal Plicataventrioids. They are odd creatures. They walk quadrupedally, but not in a way comparable to any other Anisospondyl. They walk soley on both pairs of their front limbs, with their hindlimbs being very small and located at the rear of their bodies. Because of this, they have extremely large pectoro-pelvic girdles that connect their front limbs, which makes their bodies rather stiff. This type of locomotion and stiff body morphology can be seen across all members of Plicataventria. Irrisiids have small osteoderms on their backs and are mostly omnivores. It has been reported that they use their small hindlimbs in the digging process as well as with mating.
A slighly more derived family of Plicataventroids are the Opistonychidae. Native to deserts all across Miesjeta, these creatures invoke the sense of "tortoise" more than perhaps any other Anisospondyl. They possess an anatomy that is very similar to that of the Irrisiids, though Opistonychids sport large plate like osteoderms on their back and evolved their hind limbs for a different purpose than digging. Rather Opistonychids have elongated the claws on their hindlimbs and turned them into defensive spikes. Akin to terran porcupines, Opistonychids will turn their spiky rears towards potential threats for defense and as they retain control over individual claws, they can quite accurately stab their aggressors if necessary.
The higher Plicataventria can be divided into four groups.
Most basal of these is the family known as Plicatachelidae. These animals are almost exclusively aquatic and can only be found in the Rukard Sea, the inland sea that lies on the border between southern Miesjeta and Azchèda, and the rivers and lakes that are connected to it. Plicatachelids are mostly herbivores or feed on invertebrates. Though their bodies and osteoderms are covered by a thick layer of leathery skin, their skeletons reveal that their bodies are folded. The arms below the mouths of Plicatachelids are in fact their hind limbs.
It is currently thought that Plicatachelids were pushed into the aquatic niches they hold in modern times from another, closely related group that began spreading around Bloëca around the same time the former appear in the fossil record, the Corythostegoidea. This superfamily clearly displays the folded body that Plicataventrians are known for. With rows of hard keratin covered bony plates running all along their backs, the well armoured creatures tend to be herbivores and omnivores and are often quite small.
Across the Vyaris Ocean in Lachoba and Guralta is where two other families of Plicataventrians can be found. Most notable of these are the Apelathedontidae, a family of carnivores that are among the largest terrestrial Plicataventrians. In a curious case of convergent evolution, Apelathedonts have evolved large bony projections from their mandibles akin to Tarandrosaurids. They use them for completely different purposes however, as Apelathedonts seem to have evolved these structures to help them tackle large prey. In addition, these carnivores have have and blade like claws on their hind limbs, which are located below the mouth, to help them tear into live prey and carcass alike.
The Entomosauridae are the other Plicataventrian family that can be found in the western hemisphere, with members from Lachoba all the way to southern Tlèëa. Much like their cousins, Entomosaurids are a bit more carnivorous than their Miesjetan counterparts, though the majoirity of Entomosaurids are also quite small creatures that can very often be found scurrying in the undergrowth.
Saurrhamphia
Besides the peculiar Plicataventria, there is another major branch of Eucryocardians that can be found on Eryobis, the Saurrhamphia. As much be indicated by the naming, the members of this clade all have some form of beak or keratinous structure at the tips of their mandibles. Because of this, some researchers have proposed that the ancestral members of this clade were quite specialised herbivores that would later radiate into a wider range diets.
A good supporter for this ancestral herbivory theory comes in the form of the Asaurocnidae, which have been shown to be basal to all other Saurrhamphians. This is a family of slow moving arboreal herbivores that can often be found hanging upside down from tree branches much like sloths of old Earth, except these creatures are truly ectothermic. With strong limbs and very large curved claws, Asaurocnids are experts at not moving much.
Another family of arboreal Saurrhamphians are the Salitostiliidae, whose members are best characterised by their large hind limbs that allow them to jump between the canopy. Salitostiliids often have beaks that strongly curve downwards. It is believed that this allows them to break into tree bark to access arthropods living beneath, though they also include leaves and "fruits" into their diet.
Some of the most charismatic creatures on Eryobis are members of the Microdrakonidae, which as their name would imply, can indeed look like little dragons. These somewhat skink like creatures are quite common across Guralta and Tlèëa where they mainly feed on plant matter such tubers and also feed on various kinds of arthropods. Microdrakonids are often covered in extensive bony plates, osteoderm stubs and spikes, which makes them quite well protected from a large portion of the potential predators they share their habitats with.
The Eryobiguanidae were for a long considered to be members of Eryolacertilia before DNA testing showed them to be Saurrhamphians. It is easy to see the mistake, as Eryobiguanids retain many basal Xenosauropsian traits that are commonly associated with Eryolacertilians, such as a rather lizard like body shape. Eryobiguanids, much like the terran iguanas they share their name with, Eryobiguanids are mostly herbivores, though a few omnivorous and carnivorous species also exist.
Some of the strangest faces of any Anisospondyls belong to the members of the Arpazognathidae. These Saurrhampians represent the third time a group of Xenosauropsians evolved to look and behave like iguanas since the World Scarring and all evolved on a different continent in a glaring way of convergent evolution, with the Tarandrosaurs in Guralta, Lachoba and Tlèëa, the Eryobiguanids in Miesjeta and the Arpazognathids in Hatèmica.
Much like their ecological counterparts, Arpazognathids are mostly herivores with a few exceptions. Curiously similarly to the unrelated Tarandrosaurs, Arpazognathids also display sexual dimorphism with males growing large bony structures on their heads. These often include spikes growing from the beak on the mandibles, which are often accompanied by a large arching horn that grows from between the eyes. Male Arpazognathids have often been seen duelling with other males in a way strangely reminiscent of certain beetles from Earth.
At some point though, a mutation occured in some Arpazoganthoids that made females also grow such structures. It would not have taken long for this mutation to become accompanied by an increasingly carnivorous diet as they began to use this additional weaponry to hunt other animals. It would be from such mutated populations that the Ginguridae would evolve. They would take the use of their bony growths to new extremes as they developed a unique jaw mechanism that allows them to move their mandibles up and down in addition to opening them side to side as is typical for Anisospondyls. Because of the mechanism, which bears some similiarity to that which was seen in Haidomyrmecinae ants of Cretaceous Earth, Gingurids can slam their prey against the "roof" of their jaws which evolved from the horn that grew from between their eyes. Gingurids are a relatively new family that have seen great success and quickly spread around Eryobis, filling the niche of semiaquatic ambush predators like crocodiles. The fossil record and even modern reports show that whenever Gingurids occur in the same region as Eryosuchids, the Gingurids tend to dominate and even can even replace them completely in an ecosystem.
When one observes the distribution of Parasymmetrodactyls across Eryobis, it becomes clear that they are a very "western" group, as none of their ancestrally terrestrial members can be found in Rubiëra in the east.
This points to Parasymmetrodactyls having evolved in the ancient supercontinent of Kwispuul and rather than spreading across oceans, merely drifted to new locations as tectonics pulled Kwispuul apart, with a few exceptions where some must've rafted over. Additionally, the Parasymmetrodactyls seem to be more aquatically inclined than any other kind of Anisospondyl, with a number of families independently evolving to live mostly in the water. Their specialisation in ectothermy and energy conservation allows them to fill completely different niches to Eusymmetrodactyls and Effingodactyls, which gives them an evolutionary edge like no other.
Currently they exist all over the world except in the coldest of regions and are likely to continue to do so for many millions of years to come.
The most reptilian looking and behaving of all Anisospondyls, many Parasymmetrodactyls are quite popular as pets for both natives and humans alike
