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Re: My Gr. 9 Science Fair Project: Questions



>>Parsimony would
>>have us take a more sedate line in reconstructing hadrosaur-crocodile
>>interspecific activities: the closes analogue of that situation appears to
>>be herding mammal-crocodile interelationships occuring in modern Africa.
>>There the herding mammals, despite their numbers and communication
>>abilities etc etc, still fall prey to lurking crocs and the same is
>>probably likely for the hadrosaurs and crocs all those years ago.
>
>Well, some say it's a big jump from dinosaurs to mammals, but okay.  Am
>I right that modern African herd animals are in no danger of extinction
>from the croc scourge?  Do relatively few meet their fate in the jaws of
>a croc?
>
>Wouldn't parsimony suggest the same relationship between hadrosaurs and
>crocs?

Enough meet their fate in the jaws of crocs to make croc predation a
significant factor on mammal numbers. There are very few situations where
predation puts a population at risk of extinction, and I have not been
arguing that crocs sent hadrosaurs extinct. Rather I have been trying to
counter an argument that hadrosaurs were able to evade croc predation to an
extent that croc predation had no significant effect on hadrosaur numbers.

>Crocs eat meat and swim fast with their big tails.  African herd mammals
>eat plants and swim slowly with their hoofs.  Duckbills had big tails.
>Does parsimony dictate that because they ate plants, they must have swum
>as slowly as modern herd mammals?

No, this would not be logical. But, just because hadrosaurs had deep tails
does not mean that they were good swimmers. While a deep tail can be an
effective swiming mechanism, it is unlikely that they evolved in hadrosaurs
for this purpose.

Cheers, Paul


Dr Paul M.A. Willis
Consulting Vertebrate Palaeontologist
Quinkana Pty Ltd
pwillis@ozemail.com.au