Silesaurus

[Piotr Gasiorowski <piotr.gasiorowski@inetia.pl>]

Dinogeorge@aol.com wrote
Tue, 29 Oct 2002 23:30:08 EST

<< I used Google to find four Polish newspaper websites that feature articles 
on Silesaurus. My Polish is really rusty (previously used mainly to read Polish 
stamp catalogues), but I garnered that the dinosaur was about 1.5 meters long 
and that the material includes at least one nearly complete skeleton. >>

Since I happen to be a native speaker of Polish, let me add a few details 
gleaned from a public chat with Jerzy Dzik at the Gazeta Wyborcza website (26 
Oct 2002).

There are bones of about a dozen individuals including one nearly complete 
skeleton: only the tip of the tail and some finger bones are missing.

<< Describers are PAN (Polska Akademia Nauk, or Polish Academy of Sciences) 
scientists named Jerzy Dzik and Dorota Majer. The formal description will 
appear in a forthcoming issue of JVP (the American paleontological quarterly, 
as the article calls it), so it's still a nomen nudum as far as science goes. 
At 230 million years old, the dinosaur is squarely in the Middle Triassic 
Ladinian, unless someone has recently changed the geological time scale again. 
>>

Dzik actually dates _Silesaurus_ at ca. 225 Ma ago, based on the accompanying 
index taxa and the radiometric dating of analogous sites in Argentina (which 
makes _Silesaurus_ Carnian, doesn't it?). He mentions some other large reptiles 
from the same site: _Teratosaurus_ (a rauisuchian) and _Stagonolepis_ (an 
aetosaur). I suppose a journalist had "corrected" 225 to 230 to get a round 
figure.

<< Complete name is Silesaurus opolensis, named after Silesia, a region of 
Poland and Opole, the region/locale of Silesia where it was discovered. I think 
the name has actually appeared in print, in the October 25, 2002 issue of 
Gazeta Wyborcza. There are lots of websites about Jerzy Dzik and his dinosaur, 
which he believes is most closely related to Pisanosaurus. The pix show a 
quadrupedal form that looks something like Thecodontosaurus. I've been awaiting 
a form that might serve as a common ancestor for Prosauropoda and Ornithischia; 
maybe this is it. >>

He seems convinced that _Silesaurus_ is a primitive ornithischian, secondarily 
quadrupedal and *herbivorous*, judging from the pattern of tooth wear. It might 
be the oldest ornithischian found so far, but Dzik objects to calling it the 
oldest *dinosaur*. AFAIK, the still informal name first appeared in print in 
the July 2002 issue of the Polish mutation of National Geographic. The official 
description in the JVP is apparently scheduled for the first quarter of 2003.

Piotr