References
Reference
Evans, Mark (2004) Small heads on long necks: plesiosauroid Plesiosaur skull morphology;
Small heads on long necks: plesiosauroid Plesiosaur skull morphology
Principal Author
Mark Evans
Header
Book
Book
Not Walking with dinosaurs: the swimming and flying reptiles of the mesozoic
Publisher
Leicester Literary & Philosophical Society Geology Section. Saturday School Symposium 21 FEB 2004
Abstract
The plesiosauroid skull is a rather delicate structure prone to crushing, especially in Jurassic clays and shales. The morphology of the skull therefore needs to be reconstructed before meaningful observations on structures and their significance can be drawn. The arrangement of the bones in the cheek has become regarded as taxonomically significant in recent years, yet this area is frequently poorly preserved in crushed material.
The Middle Jurassic Muraenosaums from the well-known Oxford Clay Formation of England, and its bearing on the anatomy of the plesiosauroid cheek, is a case in point. Classically, this was thought of as a low-skulled form, and an early representative of the long-necked elasmosaurs. However recent studies have allied it to its Oxford Clay companion Cryptoclidus, although the two differ in their cheek morphology. The reconstructed skull is actually quite tall, and is more similar to Cryptoclidus than originally thought. The cheek is only adequately preserved in large and old specimens, demonstrating a route for deriving different cheek patterns by heterochrony.
The recent, and somewhat controversial, recognition of the Cretaceous polycotylids as plesiosauroids, and the possibility that a new Lower Jurassic Plesiosaur may belong to this radiation, demonstrates that the plesiosauroid skull may be more diverse than previously thought.
The Middle Jurassic Muraenosaums from the well-known Oxford Clay Formation of England, and its bearing on the anatomy of the plesiosauroid cheek, is a case in point. Classically, this was thought of as a low-skulled form, and an early representative of the long-necked elasmosaurs. However recent studies have allied it to its Oxford Clay companion Cryptoclidus, although the two differ in their cheek morphology. The reconstructed skull is actually quite tall, and is more similar to Cryptoclidus than originally thought. The cheek is only adequately preserved in large and old specimens, demonstrating a route for deriving different cheek patterns by heterochrony.
The recent, and somewhat controversial, recognition of the Cretaceous polycotylids as plesiosauroids, and the possibility that a new Lower Jurassic Plesiosaur may belong to this radiation, demonstrates that the plesiosauroid skull may be more diverse than previously thought.
Language
English