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re: where have all the ornithischians gone?/Cart before horse
Tim Williams wrote:
Did your analysis include _Ctenosauriscus_?
>>>>No. As I understand it, only a vertebral spine is known. Let me know if
>>>>otherwise, but note that Arizonasaurus _is_ a rauisuchian with a high
>>>>spine, and it is not related.
>>>>Yes. Marasuchus sister to Herrarasaurus within Saurischia.
I'm curious not just about what's attracting _Silesaurus_ to _Pisanosaurus_,
but what's pulling _Silesaurus_ *away* from the basal dinosauromorphs.
>>> Name a taxon that would be a better sister taxa. I'll plug it in.
And what force is splitting _Lotosaurus_ off from the other crocodile-normal-
>>>>> The rest of Lotosaurus, other than the tarsus. Remember, croc normal
>>>>> tarsus shows up three times: in basal Rauisuchids (with Euparkeria
>>>>> showing as a precursor), in Crocodiliformes (not basal bipedal crocs),
>>>>> and in lotosaurs. The latter two as reversals from bipedal (or nearly so)
>>>>> ancestors at the base of the Archosauria.
PAUP nests everything, as you know, so I'm going to get "a hit" somewhere.
Among 124 diapsids (with no more than a few in every clade) Lotosaurus comes
out closest to Silesaurus and Pisanosaurus.
Like Jaime, I'm curious what characters unite this trio (_Lotosaurus_,
>>>> That was sent privately. I'll try to do the same over the weekend when I'm
>>>> back at the studio.
PS. Longisquama and Cosesaurus have also been PAUP analyzed. And we've all been
waiting five years for the next guy/gal brave enough to test them.
That brave guy would be Senter. His analysis is the most recent (2004) to look
at _Longisquama_. He found_Longisquama_ to be outside the Neodiapsida (so well
outside of the archosaurs), along with with the drepanosaurids. Senter didn't
examine _Cosesaurus_ directly, but it looks like a fairly conventional
>>>> Senter's paper used too few taxa (20). Taxa jump around because they are
>>>> attracted to sister taxa. Too few to choose from and you get attraction by
>>>> default, because "PAUP nests everything". In my work, I've included
>>>> everything from Gephyrostegus to Iguana and Lotosaurus, so _everyone_ is
>>>> invited to that dance. Without Huehuecuetzpalli and other squamates,
>>>> Macrocnemus and Langobardisaurus are attracted to Prolacerta as Senter
>>>> showed. Without Iguana, Sphenodon and Homeosaurus, Gephyrosaurus and
>>>> Mesosuchus are attracted to Youngina, as Senter showed. Each of these
>>>> small (smaller than 30 taxa) studies give us something to chew on, but
>>>> without the one overall study to set the blueprint up you're putting
>>>> bathrooms next to kitchens. Someone is goin to complain. Ever since
>>>> Gauthier 1986 we've been putting the cart before the horse. Once the
>>>> overall blueprint is established, we can start breaking into smaller
>>>> clades more successfully.