Wow...I cannot believe I just typed all of the those words in the title together. Today's issue of Nature magazine includes an article on a new heterodontosaurid ornithischian (Tianyulong confuciusi) from the Cretaceous of China. Not only are heterodontosaurs pretty much unknown from the Cretaceous (previously restricted to the Latest Triassic (?) and early-middle Jurassic only), this one is covered with patches of filaments similar to the protofeathers found in many saurischian taxa.
These filaments are already known from the basal ceratopsian Psittacosaurus; however, a heterodontosaurid with feathers pushes this occurence to the base of Ornithischia (Butler et al. 2008).
It is not entirely clear whether the ornithischian filaments and saurischian protofeathers are the same, but if they are this would strongly suggest that protofeathers may be plesiomorphic for Dinosauria, and it is even hypothetical now that the successive ornithodiran outgroups to the dinosaurs may have also possessed this character. Now we just need a silesaurid from these Chinese deposits now or some better preservation in the Triassic! You can read more about this here, here, and here.
REFERENCES
Butler, R., Upchurch, P., & Norman, D. (2007). The phylogeny of the ornithischian dinosaurs Journal of Systematic Palaeontology, 6 (01) DOI: 10.1017/S1477201907002271
Zheng, X., You, H., Xu, X., & Dong, Z. (2009). An Early Cretaceous heterodontosaurid dinosaur with filamentous integumentary structures Nature, 458 (7236), 333-336 DOI: 10.1038/nature07856
It was too young for a heterodontosaur, wasn't it?
ReplyDeleteThis is very cool stuff. I should point out that Sereno, Norman & Barrett have all (correctly, in my opinion) identified Echinodon, from the earliest Cretaceous of England, as a late-surviving heterodontosaurid, so another Cretaceous taxon isn't totally unexpected. However, this is the first definite heterodontosaurid from Asia, and the first definite published post-Early Jurassic heterodontosaurid.
ReplyDeleteLots of interesting stuff beyond the 'protofeathers'. Check out that dentition (which the authors barely discuss) and imagine what that critter was feeding on. Moreover, although I still favour a basal position for the group within Ornithischia, this taxon shows yet more similarities to marginocephalians (notably the reduced postpubic process)...
And suddenly pterosaur "hair" becomes highly, highly relevant.
ReplyDeletePerhaps that occurence of filamentous appendages in a heterodontosaur and also in pterosaurs is not suprising after all - developmental biologists comparing avian and crocodilian skin were saying it all along that there is a strong similarity in the embryonic epidermis from which crocodilian scales, avian scales, turkey beard bristles and avian feathers arise (and also the types of beta keratin are alike). In particular Sawyer & Knapp (2003) concluded that the ability of the epidermis to give rise to functional structural beta keratin elements was plesiomorphic for birds and crocodilians.
ReplyDeleteSawyer RH, Knapp LW (2003): Avian skin development and the evolutionary origin of feathers. - Journal of Experimental Zoology 297B: 57- 72.
This is the part where my brain explodes. IT EXPLODED.
ReplyDeleteLots of interesting stuff beyond the 'protofeathers'. Check out that dentition (which the authors barely discuss)
ReplyDeleteTo be fair, the editors at Nature kind of demanded that more focus be given to the integument; one would hope that a longer, more detailed paper is forthcoming...!
Richard Butler wrote:
ReplyDeleteMoreover, although I still favour a basal position for the group within Ornithischia, this taxon shows yet more similarities to marginocephalians (notably the reduced postpubic process)...
I would also aver that the shallow, parallel-sided jugal and the tiny humerus, along with the caudal ossified tendons, implies a close association to the base of pachycephalosaurs like Goyocephale which, had it lacked a cranium, would also likely be tied to heterodontosaurs if for no reason other than its dentition.
Yes, so far, the teeth have been very overlooked, especially what appears to be a very carnivore-like set of semi-ziphodont anterior teeth (hooked) and non-chisel-like "cheek" teeth. More support for the "omnivore" hypothesis for basal ornthischians, at least.
Very amazing blog.
ReplyDeleteRussian Bride