Re: sauropod quantity

[Dinogeorge@aol.com]

In a message dated 9/19/99 10:11:34 AM EST, smithjb@sas.upenn.edu writes:

<<  Where is this coming from, George?  First of all, if we are talking truly
 "chicken-sized" and "sparrow-sized" in the  Triassic and Jurassic, then we 
are
 talking about the Norian to the, say Toarcian, ja?  If these are the ages we 
are
 discussing, then there are not "thousands and thousands" of tracks in this 
size
 class.  Indeed, these tracks are biased towards the mid-range (from about 4-8
 inches in track-length).  If we discuss only the Newark Supergroup 
ichnofauna,
 then I would doubt that there are more than a couple hundred such tracks. >>

Just finished reading the relevant section of Lockley's The Eternal Trail, 
wherein he notes chicken- to sparrow-size theropod tracks from Navajo 
Sandstone (prints 1.5 inches long), from Connecticut, from Newark, from 
Argentina, from Brazil (Botucatu Fm.). See pp. 121-122. I believe Ellenberger 
has tracks in this size range from South Africa, too. These small dinosaurs 
were apparently distributed worldwide during Late Triassic through Late 
Jurassic times, most widespread during Early to Middle Jurassic.

These are not Coelophysis-size tracks but several times smaller. The smallest 
dinos I can think of off the top of my head that are earlier than 
Compsognathus are Segisaurus and Procompsognathus, which might have made the 
>largest< of those small theropod tracks. There are no "sparrow-size" 
nonavian dinos known from skeletal remains (maybe some teeny teeth) at all, 
period. The tracks compare in size with, but are otherwise different from, 
those of small mammals found in the same localities.

I'm not a dino tracker, so for further information and more details I suggest 
you contact the source, Martin Lockley, himself.