[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Antetonitrus

Matthew Bonnan wrote:

For someone who is not a systematist, these changes in phylogenetic interpretation lead to a whole new series of functional ramifications. Call them whatever you like, and argue about what they should be called, but what Yates, Kitching, and some others have been doing is prodding the rest of us into re-
evaluating the beginnings of the largest dinosaur giants, and that to me is what is most significant about this recent announcement.

Adam Yates wrote:

To Tim I would say that Lessemsaurus, Blikanasaurus and Anchisaurus HAVE got a whole lot more sauropod-like.

I agree with both statements (and everything else said by Matt and Adam) wholeheartedly. Above _Saturnalia_-_Thecodontosaurus_- _Efraasia_ there would appear to be a split in sauropodomorph evolution, with one line leading to sauropods (via _Anchisaurus_ and melanorosaurids) and the other leading to plateosaurs. I find this fascinating - not the least of which because it implies a shift from bipedality to increased quadrupedality occurred independently in both lines.

Anchisaurids are indeed more sauropod-like than plateosaurs. However, myself (and I believe Mickey too) were trying to douse any suggestion that by putting _Anchisaurus_ in the Sauropoda that this critter had suddenly become a big, lumbering, broad-footed quadruped. My point was that the inclusion of _Anchisaurus_ in the Sauropoda is *not* due to the fact that it fits the archetypal view of a "sauropod" - after all, _Anchisaurus_ is still a modest-sized slender-limbed runner. Rather, _Anchisaurus_ finds itself in the Sauropoda because of its new place in sauropodomorph phylogeny, which means that it is now captured by the phylogenetic definition of the "Sauropoda". I think this is terrific, and I see no reason why the term Sauropoda should be re-defined because it includes non-traditional sauropods like _Anchisaurus_.

As for the other basal sauropods... In contrast to _Anchisaurus_, melanorosaurids and blikanasaurids have long been considered "sauropod-like". Both families did include hefty-sized, broad-footed, lumbering quadrupeds. The question has been whether or not the sauropod-like traits of melanorosaurids and blikanasaurids indicated a close relationship to sauropods, or were due to convergence. The excellent work of Yates and Kitching indicates the former. Great stuff!


The new MSN 8: smart spam protection and 2 months FREE* http://join.msn.com/?page=features/junkmail