Re: Triassic dino tracks in this week's Science

[Dann Pigdon <dannj@alphalink.com.au>]

"Thomas R. Holtz, Jr." wrote:
> 
> Thulborn, T. 2003. Comment on "Ascent of Dinosaurs Linked to an Iridium
> Anomaly at the Triassic-Jurassic Boundary." Science 301: 169.
> 
> A comment on Olsen et al.'s paper last year, suggesting that a) an impactor
> is the cause of the Tr-J extinction and b) such extinction allowed the rise
> of giant theropods, among others.  Thulborn discusses trackways and prints
> from Molteno Formation of southern Africa and the contemporaneous Ipswich
> Coal Measures of southeastern Queensland, Australia (both Carnian).  These
> prints are big: one is 43 cm long, and thus Allosaurus-sized.

They've obviously lost some weight in the last five years. Thulborn 1998
has them at up to 46cm. See:

Thulborn, R.A. 1998 Australia's earliest theropods: footprint evidence
in the Ipswich coal measures (Upper Triassic) of Queensland. Gaia
15:301-311
http://www.mnhn.ul.pt/Gaia%2015%20papers/Gaia%20(15T-P301-311)-THULBORN.pdf

> In response, Olsen et al. point to features of the Aussie tracks with those
> of big pentadactyl tracks from the Carnian of North Carolina
> (Parachirotherium, which may be from pseudosuchians).  The latter can be
> misinterpreted as theropod tracks if digits I and V are poorly preserved.

In the Ipswich Coal Measures, they co-exist with much smaller
*Grallator* prints. Aren't *Grallator* considered by some to be a size
variant of *Eubrontes* (or vice versa)?

-- 
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Dann Pigdon                   Australian Dinosaurs:
GIS / Archaeologist         http://www.geocities.com/dannsdinosaurs
Melbourne, Australia        http://www.alphalink.com.au/~dannj/
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