Among modern Anisospondyls, there are few as diverse as the Eusymmetrodactyla. The bulk of their species and diversity comes from their flying members, the Stauropterygians, which were obviously able to disperse and diversify around the globe quite easily.
But the second most successful group of Eusymmetrodactyls is nothing to scoff at either.
The Monotoalosia are often considered to be the dominant macrofaunal herbivores of Eryobis. They can be found on every major landmass except Rubiëra and are usually counted among the megafauna wherever they exist.
The Monotoalosia are a rather odd looking group, even for Eryobian standards, and have an interesting but unexpected evolutionary past. Genetic testing and paleontological evidence suggests they split off from other Eusymmetrodactyls shortly after the Stauroptergyians split off, possibly placing their origin as early as the start of the Recrescian, some 106 million years ago. Their earliest and most basal members seem to have been small, gliding, rodent like animals and curiously, one family of these most basal members survived to modern times in the tropical rainforests of Bloëca, the Paleovolyidae.
The revelation of Paleovolyids as Monotoalosians was a quite recent one. It was previously assumed that they were members of Polyotoalosia that simply had only one pair of auricular filaments and a beak at the end of their mandibles. But a reexamination of their foot anatomy, in which their front feet are oriented "sideways", and some molecular testing revealed that they were in fact closer related to Kadriomorpha than to any other Eusymmetrodactyls.
It would be this discovery that led to the answer of a question that scientists had been asking since the very beginning of Eryobian exploration: how did Kadriomorphs get those odd traits?
Indeed, Kadriomorpha are ranked among the strangest looking of Anisospondyls. But not for their alien looks, no rather for the fact that they don't look like aliens. Their appearance has a lot of similarities with hoofed animals from Earth and like them, Kadriomorphs are almost all completely quadrupedal with heavily reduced visendal front limbs. Often all that remains of their former front limbs is a long spike like claw, sprouting from their shoulders.
No one could figure out why until Paleovolyids were revealed as their cousins and the group Monotoalosia was officially created. The Kadriomorphs inherited their traits from ancestors that were specialized in gliding.
It is speculated that Kadriomorphs evolved from Paleovolyid like creatures that left the trees and instead decided to make a living on the ground. They would have used their caecal front limbs and hind limbs to walk, while their visendal front limbs supported the patagium and were likely held off the ground.
Soon they would have lost the ability to climb and glide completely in favor of a terrestrial lifestyle.
Some of these early Kadriomorphs would have used their former wing arms to grab and manipulate food, eventually leading to modern creatures like the Nothrungulatids.
Others were reducing the wing arms and elongating the claws to serve as defense weaponry to attacks from above. Prokadrians and Bounindriids are leftovers from this stage.
As Kadriomorphs were becoming more and more adapted to a cursorial lifestyle, the visendal limbs became more reduced, their other legs become longer and stronger and their claws would become hooves. They became the Kadrians.
The Kadrians are easy to recognize. They often bear an uncanny resemblance to terran herbivores like antelopes, rhinoceroses and horses.
The most basal Kadrians are the aptly named Protokadrids. These creatures are some of the only Kadrians alive that still walk on their toes and just their hooves and sport visendal limbs that still very much resemble hands with long claws. Some scientists doubt whether Protokadrids aren't even true Kadrians at all and not just advanced Kadriomorphs because of these primitive traits.
All other Kadrians share a number of traits that distinguish them from Protokadrids. The most noticeable of these are their completely unguligrade feet and visendal limbs that have been reduced to nothing but a single metacarpal that supports a large claw.
Or so we thought.
Turns out there are two families of Kadrians that do not conform to these standards. The Lagokadrids of Tlèëa have two digits and thus two claws on their visendal limbs and the Camelokadrids of western Miesjeta also still have two visendal claws and do not walk on their hooves, rather being digitigrade.
Because of this, a new group was made: the Eukadria, the true Kadrians. Besides all the aforementioned traits, Eukadrians also all share a large and well developed, chambered digestive tract that extends beyond their hips and makes the base of their tails look bulbous. In addition to their beaks, they have highly specialized linguopalatal jaws that are very long for Cryptognath standards. This second pair of jaws is able slide and can move both back-and-forth and up-and-down, making them extremely efficient in chewing tough plant matter.
The Rhamphoceratids are the most basal of the Eukadrians. In the past, this family also contained a number of gracile genera that resembled other Eukadrians more, but nowadays the Rhamphoceratids are large bulky animals that are the most massive of the living Kadrians.
Eukadria knows two major branches that are ever so slightly more related to each other than either is to the Rhamphoceratids. The less "derived" of the two are the Plesiokadria. These are typically stocky and heavy set animals with primitive hooves.
The other branch, the Neokadria, on the other hand are the more typical animals people imagine when they hear the word Kadrians. They are gracile, slender legged, often vaguely deer or antelope like animals that put all their body weight on a single hoof per leg.
Curiously, the hippopotamus like Lurdukadrids of Hatèmica have recently been proven to be more closely related to Neokadrians than to Plesiokadrians, despite bearing a greater resemblance to the latter.
Back when Kadriomorphs first started appearing, the landmasses of Guralta, Lachoba, Hatèmica, Bloëca, Azchèda and western parts of Tlèëa were united in the supercontinent called Kwispuul. This may partially explain why some relatively closely related groups can be found oceans apart.
Eukdria appear to have their origin in Guralta, which is where the Rhamphoceratids, a number of Plesiokadrians and basal Neokadrians can be found.
It seems however that some groups like the Acanthatheriids and Lurdukadrids managed to get to other continents before Kwispuul had fully broken apart.
But then there the Embolokadrids of Hatèmica and the Ceratokadria of Miesjeta. The molecular clocks of these groups suggest that they only appeared after Kwispuul was already supposed to have broken up.
Some scientists suggest that the ancestors of these groups rafted over, but given the nature of Kadrians, that is rather unlikely.
Most seem to believe in the theory that there must have been island chains or temporary landbridges connecting Hatèmica and Miesjeta to Guralta at some point in the past, and that these wayward Kadrians island hopped to their current locations.
In the last few years, researchers added a new and highly unexpected member to the Monotoalosia family tree: the bizarre Bouvijasiren.
This cat sized aquatic creature was for a long time, and due to a lack of proper studying, considered to be a Brachiostomatan because of its arms located below its mouth. An actual proper examination of the animal however revealed that it was not a Brachiostome at all, but rather a Cryptognath. Not just any Cryptognath too, but a relative of the Kadriomorpha whose closest living relatives appear to be the gliding Paleovolyids.
How exactly this odd critter evolved or where it came from is not yet understood, although some fragmentary fossil evidence seems to hint at it being the last relic of a once more diverse group. All that is currently known about it is that it lives exclusively in brackish and freshwater systems of the island called Bouvija and its surrounding smaller islands in the farsouthern regions of Rubiëra.
