Re: Preservational bias revisited

[Dinogeorge@aol.com]

In a message dated 97-06-26 10:00:52 EDT, jbois@umd5.umd.edu (John Bois)
writes:

<< Then do you believe that the smallest end-K/T non-avian dinosaurs were
 smaller than one meter (and something like 30 kg.)--i.e., some sort of
 protoceratops?  I thought you had once argued that a possible contributing
 factor for dinosaur extinction was the lack of small species among their
 number.    >>

The smallest end-K-T dinosaurs were indeed less than a meter long, some
probably only 15-20 cm. They were >birds.< As far as I can tell, these were
the only dinosaurs  of this size remaining just before and during K-T times,
which is likely why only those dinosaurs survived. The very late Cretaceous
is well sampled in North America, and remains of tiny, Compy-size and
smaller, non-avian dinos just don't turn up. Virtually all other terrestrial
small-animal niches were occupied exclusively by mammals, which evidently had
progressively replaced the small dinosaurs (e.g., the smallest
ornithischians) during the span of the Cretaceous. Lack of small species is
not a contributing factor in extinction itself, but rather the reason that
dinosaurs didn't return (except, as we might expect, in the form of giant,
flightless predatory birds) in the Cenozoic.

I really should put this kind of stuff onto a BCF web site sometime, where
interested readers can refer to it, review it, comment on it, and so forth.