Yixian ornithischians

The ornithischians don’t often get much of a look in here on the Musings, however I did see several nice specimens while in Liaoning so this seemed like a good opportunity to mention them and give this huge clade (a good 2/5ths of the known dinosaurs though you wouldn’t know it from here or most other dinosaur blogs) a bit more coverage.

First off is the ubiquitous Psittacosaurus, a small and basal ceratopsian from the Early Cretaceous that is probably the dinosaur with the most known specimens. We must have several dozen here at the IVPP and I have yet to visit any Chinese collection without at least a few. There are certainly hundreds in museums and quite possibly thousands (and who knows how many that are illegally collected and exported – they are constantly turning up in foreign mineral shows). Anywhere you dig in eastern Asia in the right time and you will likely find them, I can think of at least a dozen sites in Mongolia and China plus I know of several more in Thailand and Russia too. It’s also the most diverse dinosaur known in that there are more than a dozen named and valid species described, though of course this may have a lot to do with the fact that we have so many – it may not really be any more diverse than most others. Despite the number of specimens found it has not had the attention paid to it that more charismatic dinosaurs have and this really should change – fossil tetrapods known from dozens, let alone hundreds, of specimens are rare and we can gain a great deal from their study (like growth, diversity rates, character evolution, intraspecific variation etc.) and should take the opportunity.

Next we have the little known Jeholosaurus, a small ornithischian that according to the latest study is a basal ornithopod, despite some features that would put it close to the marginocephalae (that is the ceratopsians and pachycephalosaurs) such as the skull ornaments that you can sort of see here. There’s not much to say here until the longer description of this animal appears but like many ornithischians it is known from quite a few well preserved specimens.

Finally we have the igunaodontid Jinzhousaurus ­– proof that the Jehol is not just small dinosaurs and leaves as this 5 m long animal shows. There are a number of specimens of this animal that have been found in the Yixian and somewhat unusually the ones that I have seen have tended to be somewhat crushed but far closer to being 3-D than most of the things in the formation. The holotype at the IVPP is especially nice and I happen to know a new description is on its way for this specimen at least. The one I have shown here is the not half as nice skull of a specimen in the rather appropriate Jinzhou museum. There’s not too much to see here bar the overall shape of the skull and the teeth and while the rest of the material was rather better I couldn’t get a good photo of it.

Well that is probably more on ornithischians in one post than I have managed collectively over the last 15 months so I hope it was worth the wait. Still yet more on the Liaoning trip to come so stay tuned.

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