GEOL 104 Dinosaurs: A Natural History

Fall Semester 2006
Dragons of the Sea and Air: Marine Reptiles and Pterosaurs

Not all reptiles of the Mesozoic were dinosaurs.

Many reptiles (and other amniotes) have returned to the sea:

However, aquatic amniotes have to deal with:

First reptiles (some think non-reptilian sauropsids, the sister group to Reptilia) were mesosaurs:

Most primitive relatives of Mesozoic marine reptiles were similar in general form (long needle-like teeth, webbed hands and feet, deep tail, some terrestrial ability, probably shore-dwelling or fresh-water) to mesosaurs, but later forms become more specialized for life in the sea.

Many different clades of Mesozoic marine reptiles, from almost every clade:

We will cover the most diverse and highly specialized forms: euryapsids (esp. ichthyosaurs and plesiosaurs), mosasaurs, and marine turtles.

Euryapsida: the sister group to archosaurs and their relatives (Archosauriformes). Euryapsida + Archosauriformes together are called Archosauromorpha.

Two highly specialized aquatic euryapsid groups: ichthyosaurs and plesiosaurs.

Ichthyopterygia (ichthyosaurs):

Plesiosauria (plesiosaurs):

Mosasauridae (mosasaurs):

Marine turtles:

Just as several different groups of reptiles went back to the sea, some others took to the air.

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


No evidence of direct competition between birds and pterosaurs.

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Last modified: 14 July 2006