Xenopermian Biota of the Ural Sea: Psittacops makradens, a walrodont dicynodont

The Xenopermian is a collaborative effort between Scott, Raven, Zach and myself to outline a very different, speculative world. In some ways this is not all that different than the exercises of Dougal Dixon, After Man and The New Dinosaurs. Rather than speculating on what the dinosaurs would be like if they had not gone extinct, much like his New Dinosaurs or the Spec World Project, or project into the future with After Man or The Future is Wild, our team asked the question of ‘what if the Permian Extinction did not happen?

This is the next post about the fauna of the Xenopermian in the Ural Sea region. We have talked about a ‘fossil’ and a faux controversy associated it with. We have talked about the geological staging differences in the XenoPermian timeline, and have even talked about the differences in the world in general under such a different period. We have generalized about the fauna, but now we want to get into specifics. In our first post, we talked about the first faunal member of the Xenopermian, Graviloricanasus roma, a pseudochelonid and very derived pareiasaur. Then we talked about Elyardia hensonii, a very derived anomodont. Then we talked about the alternate pterosaur, Maralae whittoni.  Last time we talked about the trematosaurine temnospondyl Chronoperifronius thassalicus.

Today we return to the therapsids.  Specifically, we are returning to the anomodonts and one rather peculiar branch of the most famous of anomodonts (dicynodonts) called we, their creators, have been affectionately calling the 'walrodont:' Psittacops makradens.

Psittacops makradens: Parrot face Walruses, erm, long teeth of the Ural Sea

Psittacops makradens is an example of a derived anomodont. Anomodonts are one of the major clades of therapsids, very derived synapsids that superceded the pelycasaurs like Dimetrodon. Other famous derviced clades are the gorgonopsids, therocephalians and cynodonts (of which mammals – and you! – are a part of).

During the Great Churn, when the Siberian Traps long erupted long and slow at the start of the XenoPermian, rather the short and quick according to our timeline, some of the dicynodonts actually adapted to being semiaquatic.  The irony is that the dicynodonts have been called semiaquatic for a long, long time, but generally were not.

This branch of dicynodonts became what the cross time paleontologists would call the Thassalotheres.  These in turn would develop clades which were more derived and specialized as forms that would be labeled based on their general form as Hippodonts, desmodonts and walrodonts.  These were not their scientific names, but work well enough for our purposes.  The hippodonts became the dominant forms in lakes and rivers.  The more gracile desmodonts became dwellers of the swampy lands.  Finally, the walrodonts would take to the open oceans.

P. makradens is modestly sexually dimorphic species having a lot of parallels with our own pinnipeds and walruses.  They come onto the beach to sun and bare their young.  They bare live young, which they take care of, but are relatively developed.  They could give birth at sea, but the sea is a dangerous place, in some ways more than land.  However, even so land is still dangerous and the the walrodonts will form colonies to protect each other and the young. 

On land, they must protect against raids by the giant gorgonopsids, gracile canid and venomous felid-like therocephalians, Xenosuchus and temnospondyls.  The latter are often a problem as the walrodonts transition from land to water or vice versa.  However, none of these are nearly as dangerous as the hovasaurs.  These newt-ish basal diapsids have developed into mosasaur-like predators in the sea where they are a real danger to the young.  They didn't develop the fish-like tail though.

The walrodonts are herbivores.  They dive to eat the kelp-like algae forests.  P makradens eats the ones growing throughout the Ural Sea, even becoming something of a deep diver since the Ural Sea is so well mixed.  They will occasionally take a shelly bivalve for the mineral supplement.  They have coevolved with the local marine forest algae where the algae grows rather fast and sometimes had been called sea kudzu.  A colony of walrodonts might mow their way through the algae forest only for it to be largely regrown in a matter of weeks.  

Psittacops makradens is not the only species of walrodont.  There are four others.  Two others are of the same genera and live in Tethys.  Psittacops erythros is common in the western Tethys on the shores of the mainland and Psittacops corvus resides in the islands and archipelagoes of the eastern Tethys.  In the Panthalassa, on the northern mainland of Pangaea coast resides Ododenodon millerensis, a very robust and heavily tusked species (pictured above).  A cogeneric species, O. amos is on the southern coast of Pangaea.  

The walrodonts would survive through the XenoPermian-Jurassic Extinction.  However, they would not make it past the Jurassic-Cretaceous transition, save for a single species.  It would die out though by the time of Middle Cretaceous during the anoxic events.  Their form would not be replicated by Juxtarodentia in the Allozoic, the surviving lineage of dicynodonts would not return to the sea.  Therocephalians would have a chubby descendant that would like vaguely like a walrus, but without the tusks in the Allozoic glaciations though.