Re: Why did small dinos become extinct?

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

----- Original Message -----
From: "John Scanlon" <riversleigh@outbackatisa.com.au>
Sent: Monday, December 17, 2007 3:30 AM

> Philip Chalmers wrote:
>
> > Despite the thoroughness of David Marjanovic's response

Sorry that I haven't provided one more; I've had little time lately.

> Might I humbly point to the success of squamates in the small terrestrial
> predator niches?  Varanoids and snakes commonly reach larger body sizes 
> than
> Compsognathus et al., are well equipped for gobbling granivores and
> insectivores but need much less energy than similar-sized mammals (or
> probably dinosaurs), and they were more or less global in distribution by
> the end of the Cretaceous after only starting to show up in the mid-Early 
> K.

This is a very good point. The terrestrial crocodiles of Outer Gondwana are 
also all Cretaceous (and, in South America, younger) in age; Asia had 
another clade of (much smaller) terrestrial crocs all the way to the 
Maastrichtian.

Furthermore, *Compsognathus* wasn't _so_ small. The famous 60-cm-long 
specimen is a juvenile. The other specimen, which is adult, was 1.4 m long. 
This comes close to the smallest flightless theropod of the Hell Creek 
Formation, *Dromaeosaurus* (1.8 m), and is surpassed by several Campanian 
and Maastrichtian gila-monsters-playing-Komodo-monitor like *Estesia* and 
*Palaeosaniwa* ( ~ 3 m).