[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Latest K dinosaurian diversity trends
----- Original Message ----
From: "Harris, Jerald" <firstname.lastname@example.org>
>>you can split the only
North American Late Maastrichtian hadrosaurid (Edmontosaurus) into 3 taxa if
you like, but it's still only the one clade, whereas in the Campanian we had
multiple clades (3-4 hadrosaurines, 3-4 lambeosaurines). So diversity is just
modified by a multiplier depending on whether you are a splitter or not.
> This doesn't make any sense. Using this same logic (using clades, rather
than species, to define diversity), one could say that there's only one clade
present in the Late Maastrichtian terrestrial gnathostome fauna: Gnathostomata.
Really low diversity, that. Or among arthropods, one could say that there's
Yes, I'm not sure I have the words as to how to put this properly. Maybe this
works: There is less morphological diversity among late Maastrichtian dinosaurs
compared to Late Campanian dinosaurs. Whether or not you split the taxa into
multiple species does not alter this. I would say that the low morphological
variation is probably reflective of true taxonomic diversity, and that most of
the described taxonomic variation is actually ontogenetic or stratigraphic,
(which are both testable hypotheses and not merely individual judgement calls).
I'd love to go into further details of species in the Hell Creek, but its other
people's (in progress) research.