[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: synapsids (was RE: pdf request)
I might add that DP, though he is a good artist when painting life
reconstructions, draws skeletal pictures without reconstructing the skull of
many reptiles (i.e. he depicts them like they are preserved: crushed, as it is
in situ) Some of his images are pretty accurate, though.
----- Original Message -----
From: "David Marjanovic" <firstname.lastname@example.org>
To: "DML" <email@example.com>
Sent: Wednesday, June 13, 2012 6:05:03 PM
Subject: Re: synapsids (was RE: pdf request)
> That said, it has been occasionally suggested that Diadectes is a
> basal synapsid, although the majority of studies place it outside
> crown-group amniotes.
Not just the majority, but all done after 1992 or so (arguably 1998),
and all with a decent taxon sampling. I like the idea, but the data
don't. Diadectomorpha and Amniota are sister-groups.
(Diadectomorpha contains the herbivorous Diadectidae, the carnivorous
*Tseajaia*, and the carnivorous, probably amphibious and crocodile-like
> I will leave it for others to comment on detail, if they wish
> (David? Mickey?). But in brief, Peter's analyses have a lot to be
> desired in terms of anatomical interpretation, methodological
> approaches, etc.
A few years ago, David Peters kindly sent me an early version of his
analysis. It turned out that:
-- he had misinterpreted at least a few published line drawings of
skulls, inferring a completely wrong three-dimensional shape from them;
-- he had no idea how to make a data matrix for specifically
phylogenetic analysis. That is, he didn't even _try_ to avoid correlated
characters. There were lots of them!
I have told him so at every opportunity, in private and in public, ever
since then. He has never even tried to argue that I was wrong; nor has
he ever claimed, let alone tried to show, that he had corrected any such
You will notice I haven't mentioned his "photointerpretation technique"
( = pareidolia) above. That is probably an additional problem even
outside of pterosaurs. Next Tuesday, on the way to Teruel*, I'll stop by
in Barcelona and have a look at *Cosesaurus* so I can compare it to his
interpretation of it, which may be entirely correct but is based on a
seriously crappy photo.
* 10th annual meeting of the European Association of Vertebrate
> The wealth of data (genetic, genomic, morphological, developmental,
> etc.) pretty securely place turtles and traditional diapsids
> together in at least some combination, and the skeletal data for
> parareptiles being closer to diapsids than to synapsids is very
> The idea of a synapsid-archosaur or synapsid-diapsid clade clade has
> a long history (Diaptosauria; early non-computerized cladistic
> analyses, etc.) And you can certainly pick out a few characters to
> support it (thecodonty, for one). But it doesn't pop out in the
> really comprehensive studies of Permo-Triassic critters.
Exactly. BTW, mosasaurs, snakes, and diadectids are thecodont, too, but
the earliest synapsids (like varanopids) are not, and the sister-group
to all other diadectids (IIRC) has an intermediate condition.