Re: patellas

[nclark@museum.gla.ac.uk]

Betty wrote:-

>why don't 2-legged, bipedal birds have patellas?
>Therapods don't have them, but they have a severe knobby bit at the 
>knee-end of the tibia that might have acted in a similar fashion to a 
>patella.

As far as I can work out some lizards have a boney growth in a tendon 
which is possibly analogous with the patella of mammals.  I guess it is 
just a feature that evolved in the mammals and didn't develop in the 
retiliomorphs.  Dinosaurs were evolving along a particular line from 
ancestors that hadn't developed this feature (ie: I don't know why they 
don't have this feature but I guess the "knobby bit" was an evolutionary 
adaptation that went someway towards compensating for the lack of a 
patella???).

Neil