Concepts and Controversy

Bipedal or Quadrupedal Page 2

Pterosaur Pelvii

Other conclusions have been based on the morphology of the pelvis. In vertebrates with a bipedal stance the pelvic girdle is often fused along the ventral surface and across the right and left halves. This fusion allows the hip socket to be placed outward and downward. In vertebrates that have unfused pelvis girdles, the limbs tend to sprawl to the sides; the hip socket is still placed outward but has been rotated upward.



Top View
Pteranodon (fused)

Lateral View
Rhamporhynchus (unfused)

Top View
Pteranodon (fused)

Top View
Rhamporhynchus (unfused)

© 1991 Christopher McGowan
Dinosaurs, Spitfires & Sea Dragons.
ons.

Amongst Pterosaurs there is evidence for both a fused and unfused pelvis. In the Rhamphorhynchoidea, the pelvis seems to be predominately unfused (Rhamphorynchus), however there are examples of genus that have a fused pelvis. The Pterodactyloid also show this disparity; there are examples of both once again. The question should be asked if pelvic structure is even indicative of stance and locomotion.

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© Patrick Lyons 1998.