Xenopermian Biota of the Ural Sea: Palonatator beccus, a desmodont 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.  Last week, we looked at the walrodont, Psittacops makradens.   

This week we are going continue with the anomodont therapsids with a some of the close relatives of the walrodonts, the desmodonts.  Specifically, we are going to be taking a look at Palonatator beccus.

Palonatator beccus is an example of another fictional and derived member of the clade Thassalothere which are a clade of the dicynodonts, an important group within the anomodonts.  These are in turn therapsids like the gorgons, therocephalians and cynodonts.  That last is inclusive of the mammals like you, you hairless ape, you!

During the great Churn of the XenoPermian, the dicynodonts branched out into different clades.  The dicynodonts were already very successful herbivores and as the innovation took place within the clade, the dicynodonts started to exploit new resources.  One of these was the waterways.  It had long been thought dicynodonts were semiaquatic, but it turns out they were not by and large in our time line.  Approximately 250 million years ago, when the Siberian Traps started erupting, the basal most thassalothere took to the swampy regions.  From there, they branched out into what would be informally called the hippodonts (river dwellers), walrodonts (sea residents) and desmodonts (swamp dwellers).

The desmodonts are in some ways more derived than their cousins.  They developed a parasagittal stance convergent with the neodicynodonts.  They also were rather more gracile than most of the other thassalotheres.  They picked up a number of traits in their adaptation to the water that reminded of the desmostylians.  Hence where they got their informal nickname.  However, they were very much dicynodonts and retained the beak and grinding mill.  One of the most striking differences is that they have lost the canine which the dicynodonts are most famous for.

However, they are nowhere as nearly derived as the walrodonts, of course.

Palonatator beccus is a pretty generic member of the clade.  They, like their relatives, inhabit swampy ground where they can eat both aquatic and waterside flora.  They are relatively quick and can out run many larger predators and those they cannot, they run into deeper water where the predators fear to tread.

They do have problems with the temnospondyls and reptilomorphs inhabiting the waterways of the swamps.  Their young are the most vulnerable.  However, on land the giant derived gorgons are dangerous even tot he adult P. beccus.  However, moving in herds does help with the predator problems.

The desmodonts are confined to the Ural Sea and along the Tethys Sea.  They are not, largely due to being unable to spread along the coastline, resident in the deltas of the Panthalassa.  Speculation is the waters are simply too cold.

The desmodonts will exist for approximately 25 million years.  They originated 10 million years before the current snapshot of the XenoPermian.  They will last until the X-J Extinction which is coming up rather soon, in 15 million years from the time of the snapshot we have here of the XenoPermian.  The Mesozoic will have different animals fill the roles the desmodonts fill.