Cladistics: Rubieroptera

Stauropterygians are a very old group. Possibly diverging as early the late Thyellian and being even older than the Monotoalosia, they are the most basal living Eusymmetrodactyls.

But they are by no means primitive. In fact, Stauropterygians are the single most diverse species rich and diverse order of Anisospondyls to have ever existed.

But because they are so old, they have a decent number of ancient "leftovers" among their ranks.

While there a good amount of those leftovers are true relics and often the last remaining members of their respective prehistoric families, there is one group of basal Stauropterygians that does actually appear to be a (mostly) monophyletic grouping: the Rubieroptera.

This group of mostly, but not exclusively flightless Stauropterygians are hypothesized to have evolved from some of the very first Stauropterygians to reach the paleo-continent Magna-Rubiëra, which ofcourse was completely isolated from the paleo-continent Kwispuul where Stauropterygians evolved. Even to this day, the majority of morphological diversity among Rubieroptera can be found in the Rubiëran archipelago, from which the group draws its name.

The most basal living members of the group look exactly like what one would expect a secondarily flightless basal Stauropterygian to look like.

They are usually small bodied creatures no bigger than a turkey, with a long tail, a short beakless but toothed skull and small arms with clawed fingers and often a small remnant of what used to be the wings.

It is likely all other Rubieropterans evolved from animals like this.

One noticeable family of Rubieropterans that still live in Rubiëra are the Thanatrigidae, a family of large bodies predators that are the undisputed terrestrial apex predators of the Rubiëran isles. Some species like Thanatrix imperator can weigh up to 400 kilograms. These fierce predators often hunt by lying in ambush or lunging from trees and will try to impale their prey with their large and strong claws before delivering the killing bite. 

A family of Rubieropterans that are relatively closely related to the Thanatrigidae are the Inermavidae. The bulk of this family lives in Augadrian Tlèëa, with some species also occuring in Wyndraë and Lehseppi. These flightless and in fact completely armless Rubieropterans did not reach Tlèëa by island hopping, but were brought there by plate tectonics as Magna-Rubiëra broke apart and the Inermavids were marooned on the northern part that drifted towards Tlèëa.

The largest group within Rubieroptera is the Exypnophonea. The most basal members of this group are small to medium sized arboreal carnivores that live all over the Rubiëran archipelago. Uniquely among Stauropterygians, Exypnophoneans have wrists that can be pronated and possess opposable "thumbs", allowing for incredible maneuverability in the canopy.

This, combined with their high intelligence, makes such Exypnophoneans a threat for everything that lived in the trees in the Rubiëran isles.

But a strange thing happened when some Exypnophoneans got stranded on Lotharca when it broke apart from Magna-Rubiëra. As the landmass started becoming more arid and the forests the Exypnophoneans called home started disappearing, they were forced to adapt or go extinct. And adapt they did.

From these Exypnophoneans that were forced out of the trees evolved the Keshtaridae, a family of large to very large hypercarnivores. With their long legs, straight backs, long tails and large arms and claws, they bear some resemblance to the Megaraptorids of Cretaceous Earth. Like them, the Keshtarids mainly hunt by using their sharp claws to inflict deep slashing wounds and cuts on their prey to induce massive blood-loss. 

Curiously, they evolved their caecal pair of front limbs to be permanently held below the mouth and act in tandem with the jaws, an adaptation akin to the Brachiostome condition. 

These claws have been observed to be used to help manipulate food, serve a function in communication and to be used to dig deep into (often still living) prey. Additionally, the skin between these arms has grown together and has created a pouch which they often use to transport their young, food and trophies.

Which is perhaps the most terrifying aspect of the Keshtarids. They are extremely intelligent.

They are social creatures that typically live in family groups, communicate through a great number of vocalizations and body language and have been observed to use tools and elaborate schemes to hunt their prey. 

Just exactly how intelligent they are has not yet been determined, but it seems that all of them are at least on par with Hominids and Corvids, although some legends among the natives suggests that they are able to understand and even speak the languages of the native tribes they share territory with.