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Re: Crocodile program on Discovery channel
On Fri, 13 Oct 1995, Achut Reddy wrote:
> Jerry D. Harris writes:
> > Yes, crocs were around before
> > the dinos (although the eusuchians didn't pop up 'til what, the
> > Cretaceous), but in the sense of "what animal filled most of the global
> > niches of big terrestrial reptile after the dinosaurs?," crocs fit the bill
> > nicely. (coupled, methinks, with big birds!)
> But the crocs _didn't_ fill most of the global niches.
> They are found only in and around rivers. They certainly did
> not have anywhere near the range that the dinos did.
> In the Tertiary, mammals and birds filled more niches
> than crocs.
The believe that crocs have changed little since first appearing
in the late Triassic over 225 mya (_around_ the same time as the earliest
dinosaurs :o)) is a common one. Living crocodylians (alligators,
crocodiles, and gavials), while confirming to the standard eusuchian base
plan, give no hint of the vast range of diversity of those now extinct.
Indeed, the niche-filling capabilities of crocs should not be
underestimated. Early crocodylomorphs such as sphenosuchians and
protosuchians appear to have been gracile, quick-moving terrestrial
predators. It wasn't until the Middle Jurassic that crocodylomorphs
adopted the amphibious mode of life they came to dominate so successfully.
However, these taxa, known as mesoeucrocodylians, in addition to the
classic amphibious ambush predator, filled many roles. Thallatosuchians
successfully adapted to marine life, evolving flippers and a heterocercal
tail. Hsisosuchians and sebecids seem to have been terrestrial, evolving
laterally compressed snouts and trechant, serrate teeth like those of
carnivorous dinosaurs - traits also found in several eusuchian taxa which
may also have been terrestrial (for example, pristichampsines and
mekosuchins). The relatively short-snouted notosuchids may also have
been terrestrial. The blunt, intricately fluted teeth of uruguaysuchians
and some notosuchids were very similar to those of herbiverous dinosaurs
and lizards, suggesting these animals may also have been herbiverous.
It's just a shame things like this aren't around today :o(
Vertebrate Palaeontology Laboratory
School of Biological Sciences
University of NSW