|A gorgeous new specimen of Hupehsuchus (ZMNH M8127).|
A new taxon was briefly reported in Carrol & Dong (1991) but they noted that since the specimen (IVPP V4070) lacked any solid bones—only natural casts of the skeleton—it would not do as a holotype. In 2010, a second specimen (WGSC V26020) of this mystery taxon was discovered and prepared. Thankfully, it consists largely of a bony skeleton. Nonetheless, it is clearly a second individual of Carrol & Dong’s mystery animal. In 2015, Chen et al. named it Eretmorhipis carroldongi.
|That's WGSC V26020 on top and IVPP V4070 on the bottom.|
While the two specimens differ in some minor ways, the authors still confidently consider them to be the same species. Additionally, Eretmorhipis differs in significant ways from Parahupehsuchus, so they are not synonymous. Further, Chen et al. did not refer the still-undescribed “polydacylous hupehsuchian” (briefly described in my last post) to Eretmorhipis based largely on the fact that, despite being ontogenetically younger, it has two full extra ossified digits in the hand.
|The foreflippers of Eretmorhipis.|
Now, we still need somebody to fully describe SSTM 5025—the “polydactylous” hupehsuchian. I cannot fathom why this hasn't happen yet, given all the other hupehsuchians being described lately.
|That's SSTM 5025's forelimb on the far left. Freaky.|
|The Triassic was a wild time for all of us.|
On to a slightly different topic: you may recall that Motani et al. (2014), in their description of short-snouted ichthyosaur Cartorhynchus, erected a new taxon—Ichthyosauromorpha—to include the last common ancestor and descendants of Ichthyosaurus and Hupehsuchus. In other words, hupehsuchians are ichthyosauromorphs. Basal ichthyosaurs and hupehsuchians share a number of subtle features that I won’t get into here.
|Here's Cartorhynchus, who totally has a snub-nose.|
|Which means this must be Sclerocormus. Note the very long tail.|
It could also just mean that ichthyosaurs hadn't evolved deep-diving capabilities yet, which they eventually did in the Late Jurassic.
So I wonder what Cartorhynchus, Sclerocormus, and hepehsuchians were eating, and why did they go extinct?
Certainly, Hupehsuchus and its cousins weren’t being subjected to intense competitive pressure by other lunge-feeders--even if Shatasaurus and Shonisaurus were filter-feeders, they were not contemporaries. Maybe they experienced an ecological shift that affected their favored prey? Certainly, hupehsuchians must have been vulnerable, as they all lived at the same time and in the same place. Snuffing out the entire group might not have been too difficult.
*Why not Cartorhychidae?