Tetrapod Zoology

Long-time blog readers will know that I am atrocious at keeping promises. And I will confess that part of the reason for titling an article 'Goodbye Tetrapod Zoology' was to cause a burst of panic, a rash of visitors (the strategy didn't really work: look at the counter... no spike on the graph). In seriousness, fear ye not oh followers, as I will indeed keep the blog ticking over, it's just that the only things I'll post will be short and sweet. And, unfortunately/fortunately, some bits of news come in that just demand a quick write-up...

Lurking in the Tet Zoo shadows are a number of professional palaeontologists, zoologists, artists and other workers whom many of you would be thrilled to be rubbing proverbial shoulders with. Obviously I'm thrilled (and sometimes a little terrified) to see that I'm attracting such people. I won't name names, but on this occasion I have cause to: Mike Skrepnick (website: Dinosaurs in Art) is a regular visitor, and after the brief post on caseids he has provided both images and some awesome information. In the caseids article, I included a photo of the late-surviving Russian taxon Ennatosaurus. It turns out that Mike had reason to produce several life restorations of Ennatosaurus when he worked with Hilary Madden (based at Robert Reisz's lab: she worked on Ennatosaurus for her master's thesis). With Mike's permission, I'm reproducing those images here: this is a world first, and I'm very proud to showcase entirely new work depicting such rarely-illustrated creatures (when writing the caseid post I was tempted to finish it with another of my laments about the lack of good artwork, but I've made this point enough times already, what with the aetosaur and temnospondyl articles, and don't want to become tedious). The images are © Mike Skrepnick, all rights reserved, used with permission.

The illustration shown at the top of the article depicts a group of Ennatosaurus on a Permian hillside; they are accompanied by the low, scrubby cordiate Rufloria and the conifer Walchia. The Ennatosaurus skeleton that I showed previously (it's about 40 cm long I think) is apparently of a juvenile, and adults may have approached the giants like Cotylorhynchus in size. Big caseids like Ennatosaurus were living alongside biarmosuchians like Phthinosuchus and big dinocephalians like the predatory brithopodids Brithopus and Deuterosaurus and thick-skulled herbivorous tapinocephalids like the gigantic Ulemosaurus (Kemp 1982). Dicynodonts were doing well in Europe and southern Africa, but were rare in Russia at this time (King 1990). Anyway, some of these 'new' synapsids were big, reaching and exceeding 4 m in cases, so caseids had now been joined by other, more recently evolved giants.

As you can see from the black-and-white Skrepnick picture above, Mike confirms that caseids were likely to have been specialised diggers. Those of you wondering how the animal that owned the Oklahoma Cotylorhynchus skeleton (go here and here) might have reached the ground with its mouth will be interested to know that Madden and Reisz feel that the shoulder girdle in that specimen (and others) has been wrongly positioned, and needs to be raised so that the shoulder glenoid is higher. Furthermore, the head and neck needs to be repositioned closer to the ground. A more accurate depiction of the life posture is shown in the adjacent picture supplied by Mike (© Mike Skrepnick, all rights reserved, used with permission). The animals make more sense this way - but of course they still look plenty weird.

So there you have it. Thanks again Mike for all this - very much appreciated. Finally (before I get back to the day job), what was that weird sauropod? Yes, it was a sauropod and not a Mesozoic dead-end roller-coster. Supplied by David Hone (of Ask A Biologist fame: remember to visit and ask any question you like... within reason), it depicts the recently unveiled skeleton of the titanosauriform Huanghetitan ruyangensis from the Upper Cretaceous Mangchuan Formation of Henan Province, China. Huanghetitan was described in 2006, with the type species being H. liujiaxiaensis (that's a lot of vowels), and in 2007 the type species and the new one H. ruyangensis were awarded their own 'family', Huanghetitanidae (Lü et al. 2007). With ribs at least 2.93 m long, H. ruyangensis is apparently the dinosaur with the 'deepest known body cavity from the Cretaceous of Asia'*. H. ruyangensis is known from sacral vertebrae, part of the tail, some ribs and part of the pelvis, so the neck and head you see here are reconstructions based on those of other sauropods. If Huanghetitan really is a basal titanosauriform, you might predict that it would have had a shorter, deeper more brachiosaur-like skull and far longer and much more gracile cervical ribs that overlap with one another, but what the hey.

* This prompts the tongue-in-cheek question: ok, now we know where the body cavity was from, but where was the dinosaur from? That's not the first time that wording like this has been used: the therizinosauroid Beipiaosaurus was published as 'A therizinosauroid dinosaur with integumentary structures from China' (Xu et al. 1999). So, ok, the integumentary structures were from China, but where was the dinosaur from?

So, as you can see, my 'goodbye' was perhaps somewhat over-rated. As I've said, I will keep the blog ticking over, but don't expect longish articles, like this one. Unless anything desperately cool or ugent comes along. Which it will.

Refs - -

Lü, J. Xu, L., Zhang, X. & Hu, W. 2007. A new gigantic sauropod dinosaur with the deepest known body cavity from the Cretaceous of Asia. Acta Geologica Sinica 81, 167-176.

Kemp, T. S. 1982. Mammal-like Reptiles and the Origin of Mammals. Academic Press (London).

King, G. 1990. The Dicynodonts: A Study in Palaeobiology. Chapman & Hall (London, New York).

Xu, X., Tang, Z.-l. & Wang, X.-l. 1999. A therizinosauroid dinosaur with integumentary structures from China. Nature 399, 350-354.