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Re: Why did small dinos become extinct?



----- 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).