Fossil Record

 

Nothosaurs are known from the middle to late Triassic Period (245-200 million years ago). Fossil finds mostly come from Europe and China. Nothosaurs were named in by G. von Meunster in 1834.

 

Plesiosaurs are known from the early Jurassic to the end of the Cretaceous period (200-65 million years ago). The fossil record of plesiosaurs is very good, and many complete specimens have been found. The first complete Plesiosaurus specimen was discovered by famed Victorian fossil hunter Mary Anning in 1823. Many more plesiosaur fossils have been found since, on every continent of the world.

 

Skull of Pliosaur: Plesiosaurus macrocephalus. Found in Lyme Regis, Dorset.

 

Placodonts are known from the middle and late Triassic (245-200 million years ago), and have been found in Europe, North Africa and the Middle East. The first specimens were discovered in 1830 by Georg Munster, and the placodonts were recognised as a new group of reptiles by Richard Owen in 1858.

 

The earliest known ichthyosaurs are from the early Triassic (250 million years ago), and are found mainly in China and Japan. The last Ichthyosaurs occurred in the mid-Cretaceous (90 million years ago), when they became extinct.

Mary Anning is also responsible for the finding of many ichthyoosaur specimens, most of which were discovered in the Jurassic limestone cliffs of Lyme Regis, Dorset.

Some ichthyosaur specimens have been found containing embryos (as in the pictire below), or in the process of giving birth, providing evidence that they gave birth to live young.

 

Ichthyosaurus cf. communis. Found in Somerset in 1985. This female was pregnant when she died. The white arrow indicates the position of the embryo.

 



Author: Rachel Jennings
Last updated: 22/11/2005
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Websites produced by students on the MSc Palaeobiology programme in the Department of Earth Sciences at the University of Bristol for academic year 2005-6