Re: New theropod (or is it?) from Poland

[David Marjanovic <david.marjanovic@gmx.at>]

> To forestall the departure of David Marjanovic... :)

To anticipate my return from triassotherapy (Â Jan BrejÅa)?

Yes, on Thursday we* all went to Lisowice OOPS Lipie ÅlÄnski**, where the 
museum was opened for the public***, and we saw the humongous dicynodont and 
the supposed theropod. The site is thought to be Rhaetian or perhaps late 
Norian, thus much younger than the Carnian KrasiejÃw, and the sediment is 
different -- in KrasiejÃw it's red and green marl (mostly red = iron-III, 
but green = iron-II in some layers and around most fossils), while in Lipie 
ÅlÄnski it's uniformly gray and contains lots and lots of gagate, a kind of 
coal. The excavations are ongoing, and new finds are being made constantly.

* Participants in the excavation in KrasiejÃw, the site where *Silesaurus* 
comes from.
** After the opening ceremony, several people got very angry at Tomasz Sulej 
because the National Geographic Polska article says "Lisowice", which is the 
community that Lipie ÅlÄnski belongs to, rather than just saying "Lipie 
ÅlÄnski". It was, in any case, not his fault...
*** Pompous ceremony with a press conference, three mayors, a priest (hey, 
it's Poland), cutting of ribbons, and the like. Nice to see paleontology is 
taken seriously :o)

> David thinks (like some others) the "Dragon" may in fact be a hybrid of 
> theropod and "rauisuchian" material.

The "others" are Daniel Madzia and VladimÃr Socha, who alerted me to the 
possibility. The femur has an inturned head, which means it's not 
rauisuchian and is probably dinosaurian; the braincase is said to be 
unambiguously dinosaurian, which is something I can't tell and am willing to 
believe at face value; but all the rest could be rauisuchian, and the 
maxilla and the jugal clearly are rauisuchian. The antorbital fenestra was 
very small, far away from the ventral margin of the maxilla, and had a 
sharply tipped rostral end instead of a round edge; the lateral temporal 
fenestra was placed far more ventrally. Both features occur throughout 
rauisuchians and never in theropods. The condition looks identical to that 
of *Postosuchus* and *Teratosaurus*. The dentary also looks like that of 
*Postosuchus* (at least). Even the humeri could be rauisuchian; I recommend 
a comparison with the paper on *Postosuchus* in the latest JVP (June 2008).

Importantly, the parts of the skull between the premaxilla, maxilla and 
jugal on the one hand and the braincase on the other hand are so far 
unknown. Also, I don't know which teeth the enamel was examined of; there 
are many isolated teeth in the site.

> - the workers took this as one of the possibilities from the beginning;

In that case I'd really like to see an explanation for at least the 
antorbital fenestra.

> - the mixture of primitive ("rauisuchian"-grade), through coelophysoid, up
> to advance tetanuran features is expected in a big Late Triassic theropod;

Erm... no, it isn't. Especially the presence of _derived_ rauisuchian 
features like those mentioned above is totally unexpected, and I also don't 
see why "advanced tetanuran features" should be there.

> - foot tracks (and some of the bones, like femur) undoubtly point to a big 
> theropod, most parsimonously would be to assume that's the same animal.

A completely unknown amount of Triassic "theropod" tracks was made by 
rauisuchians like the dreaded *Effigia* and *Poposaurus*. (Well, not 
completely unknown -- those with hand prints are obviously not from 
theropods.)

To sum up:

- The dicynodont is genuine. Very big, and very late. I'm not really 
surprised, because the Triassic-Jurassic boundary mass extinction came 
later.
- It's an end-Triassic site, so I'd be surprised if theropods were 
completely absent, and indeed some material -- the Dragon's femur, the 
braincase, the material called coelophysoid -- may well belong to them, as 
may some or all of the footprints (but not necessarily all of them). In 
other words, the claims of "the first Polish dinosaur" may well be 
justified.
- However, most of the Dragon could be rauisuchian, and some of it almost 
certainly is. I'd be surprised if it were specifically *Teratosaurus 
silesiacus*, though, because it's around 20 million years younger than the 
type material of that "species".