We visited the Academy of Natural Sciences at Drexel University in a mad rush. Fortunately, we snapped photos to capture a lot of information because the Academy has an excellent exhibit focusing on Paleozoic animals, and Permian vertebrates in particular.
Configuration of land and seas during the Permian.Diplocaulus model, actual size. Related to present-day newts and salamanders, I believe.Ennatosaurus an early synapsid.Ennatosaurus, rear legs. Note that they still had scapula homologs rather than hips.Dimetrodon, another synapsid.Dimetrodon rear ‘scapulae’ had not fused to the vertebrae to become hips yet.Dicynodon, view of rear legs. Here, some fusion to the adjacent vertebrae has begun.Lystrosaurus, a very successful and common land animal of the late Permian.Rear scapulae have evolved parallel to the spine, and probably were linked to it by short, strong tissues. They have also lengthened forward and rearward to support more advantageous leg-muscle configurations.Inostrancevia, a gorgonopsid. Pre-Mesozoic animals got big. Roughly the same size as most Jurassic dinosaurs and most Miocene/Pliocene mammals. The massive Cretaceous dinosaurs are very uncharacteristically huge, relative to the vertebrates that came before and after them over the last 250 million years.Inostrancevia hips and rear legs & feet.
