GEOL 104 Dinosaurs: A Natural History

Fall Semester 2016
Dragons of the Sea and Air: Pterosaurs & Marine Reptiles

DRAGONS OF THE AIR: PTEROSAURIA:
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.


DRAGONS OF THE SEA: MESOZOIC MARINE SAUROPSIDS
Throughout Earth History, many reptiles (and other amniotes) have returned to the sea:

However, aquatic amniotes have to deal with:

First reptiles to return to an aquatic life were mesosaurs:

Most primitive relatives of Mesozoic marine sauropsids 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 sauropsids, from almost every clade:

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

A reminder of amniote phylogeny:
:

Euryapsida: more closely related to Archosauria than to Lepidosauria, so part of the larger clade of Archosauromorpha. Euryapsids:

Ichthyopterygia (ichthyosaurs):

Plesiosauria (plesiosaurs):

Mosasauridae (mosasaurs):

Marine turtles (Chelonioidea):

Recent work shows that the pelagic ichthyosaurs and plesiosaurs (and possibly the mosasaurs) had an elevated metabolism, more like endotherms than ectotherms.

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Last modified: 15 August 2016