On the origins of Dimorphodon and Eudimorphodon

At the base of the Pterosauria
there was one false evolutionary start that gave us Austriadactylus (the Austrian specimen) and Raeticodactylus. Thereafter the clades kicked into full gear with the basal dichotomy, dimorphodontids (which begat anurognathids) and eudimorphodontids (which begat everything else.)

Knowing that a picture tells the story here are the players (Fig. 1):

The origins of Dimorphodon and Eudimorphodon find a common ancestor close to Austriadactylus (the Italian specimen) and prior to that, the basal pterosaur, MPUM 6009. All are Late Triassic except Dimorphodon. The robust skull of eudimorphodontids suggests piscatory (fish eating) while the fragile skulls of dimorphodontids suggests insectivore. The enlarged naris was a legacy from the Italian specimen

The origins of Dimorphodon and Eudimorphodon find a common ancestor close to Austriadactylus (the Italian specimen) and prior to that, the basal pterosaur, MPUM 6009. All are Late Triassic except Dimorphodon. The robust skull of eudimorphodontids suggests piscatory (fish eating) while the fragile skulls of dimorphodontids suggests insectivore. The enlarged naris was a legacy from the Italian specimen

The basic dichotomy of dimorphodontids and eudimorphodontids (Fig. 1) set the pace for the rest of pterosaur evolution. One emphasized the longer, leaner snout of a fish and tetrapod eater while the other had a taller, more fragile and ultimately wider rostrum (in anurognathids) of an insect eater.

You can see (Fig. 1) with such short fore limbs and long hind limbs, with toes under the center of balance at the shoulder glenoid (arm pit) that quadrupedal locomotion was something that would have to be invented in the future of these Triassic clades.

BTW
Yesterday’s note on Atopodentatus garnered about twice as many viewers. Let me know why all the interest because I don’t have a clue.

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