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Unwin's ternary diagram question
A few years back (2001?) David Unwin was showing a ternary diagram based on
femur, tibia and metatarsus lengths, I think. Only saw it briefly in a PPT
presentation. Does anyone know if it has been published?
I bring it up because I just finished playing with Jim Clark's ternary diagram
(Nature Feb 26, 1998) of the three digits in pedal digit 3 of pterosaurs and
birds. The spread is a little larger than Jim lets on. Batrachognathus comes
out on top of the swift. MPUM 6009, the basal pterosaur, comes out below and to
the right of rhea. Austriadactylus joins the most of the birds in the middle.
The reduction to a disc of p3.2 in most pteros moves most of them to the right
of the diagram, as Clark indicates, but the trickling few with all the
variation were left out.
IMHO the difference lies more in the way birds sit on branches without using
their hands, while most pterosaurs appear better suited â?? from the golf grip
on the lateral pedal PILs + their hand claws â?? to cling to tree trunks. In
other words, the abilities and niches of pteros and birds probably cannot be
compared on the basis of the proportions of pedal digit III.