MadSci Network: Evolution

Re: Why did turtles lose their teeth and get beaks?

Date: Mon Apr 14 10:59:35 2003
Posted By: David Hubble, Consultant/Owner
Area of science: Evolution
ID: 1046288619.Ev

Hi Mark

Good question, however as far as I know, nobody has really worked out the 
answer yet. The earliest fossil turtles found so far are from Germany and 
Thailand in rocks from the late Triassic period, about 225 million years 
ago. The oldest, called "Proganochelys", still had a few teeth as well as 
its beak but was otherwise similar to modern turtles with a full shell. As 
yet nobody has found an intermediate form to show exactly how turtles 
evolved, but other creatures with beaks instead of teeth existed too. 
During the late Permian period (250 million years ago), reptiles 
called "dicynodonts" also had beaks that they used to cut up the plants 
that were their food. So, maybe turtles developed beaks for the same 
reason - as an efficient feeding mechanism  - but at present all we really 
know is that turtles came from an evolutionary branch of egg-laying 
animals in the late Carboniferous period about 300 million years ago, and 
then developed very differently from all other reptiles into the animals 
we see today.

I hope that helps even though there is no definite answer - maybe someone 
will discover it soon.


Dr David Hubble, UK


1. The Book of Life - edited by Stephen Jay Gould, published by Hutchinson.
2. Vertebrate Life - by F. Pough, J. Heiser and W. McFarland, published by 

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