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GEOL 104 Dinosaurs: A Natural History

Fall Semester 2017
Dragons of the Air: Pterosaurs


Detail from "Azhdarchid in Flight" by Mark Witton

Key Points:
•Cladistics (phylogenetic systematics) is a method for approximating the evolutionary relationships among taxa.
•Cladistics works by trying to reconstruct the pattern of common ancestry rather than finding direct ancestor-descendant relationships.
•Not all traits are equally useful for reconstructing phylogenetic relationships: only shared evolutionary transformations help us determine phylogenetic patterns.
•Phylogenetic information can be used as a basis for taxonomy; as a means of inferring missing and ancestral information; and for determining the time of divergence between lineages.

Not all reptiles of the Mesozoic were dinosaurs. There was a diversity of reptiles on land, and also in the sea and in the air.

A number of Permian & Triassic gliding reptiles, but only two powered flying groups:

Pterosaurs:

No evidence of direct competition between birds and pterosaurs.

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Last modified: 6 July 2017

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Detail from "Dimorphodon on the Chase" by Mark Witton