Posts Tagged 'Anchiornis'

Multiple specimens

This post is, in a way, an excuse to show off this specimen of Anchiornis which I was surprised to see on display at the IVPP. Surprised because I hadn’t seen it before and didn’t know it was in the collections, but even in these times of endless publications, not all specimens get illustrated in the literature. This leads me reasonably onto the area of multiple specimens of taxa, something that does seem to cause confusion for some people, perhaps because it’s simply never discussed.

While the fossil record is famous for being incomplete, and while a great many vertebrate taxa are named from a single and often very incomplete specimen, that does not mean that all fossils species are like that. Predators are, naturally, rather rarer than herbivores but there’s over 30 specimens of Allosaurus known (and probably quite a few more knocking around in various basements) over 15 Tyrannosaurus and who known how many of Coelophysis. Even so, often only the single best specimen of a given species is illustrated in a paper and that one image can be endlessly reproduced in papers or in books and these days online too. That means it can be easy to fall into the trap of thinking these is only one specimen out there when there may be dozens.

Microraptor (yes, that again) serves as a good example – search for images of this genus and you’ll find hundreds of photos of the holotpye of M. gui. You could be forgiven for thinking that this was the only one, but this was the second species to be named in the genus. On top of that, the holotype was one of six specimens listed in the 2003 description that named M.gui. Since then plenty more specimens have been uncovered and are in various museums but few have been described since they don’t contain much more information than is available in the holotype and are unlikely to be anyone’s top priority.

Given the readership of this blog, this is likely stating the obvious, but the short version is that (as noted before) there are a lot of fossils out there, and often far more than you might realise. Certainly there are a lot more specimens of some taxa that you might ever see going by images used by the media, or books, or even in some cases the scientific literature itself. After all, if you want to quickly and effectively communicate what Microraptor looks like, you’d include a photo of the M. gui holotype and not a half incomplete one with no skull and no feathers preserved. However, that won’t stop the others from existing or any information on the genus as a whole being based on multiple specimens, something that seems to bypass at least a few people from time to time.

Anchiornis and the temporal paradox

So after the original Anchiornis paper and now the follow up things should be pretty clear about the identity of this animal – it’s a troodontid that looks an awful lot like a basal bird. This is no surprise given that birds and troodontids are very close relatives and that Anchiornis is an especially basal troodontid and thus is probably closer in appearance to other basal birds than many others of its kind, and of course the original specimen in lacking a head did not have all the characters that might have helped us solve this earlier. So now onto the issue of time and evolution which is nicely demonstrated here by the new find – the oft quoted and very misleading temporal paradox.

Continue reading ‘Anchiornis and the temporal paradox’

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