SEA DRAGONS

  In the seas of the Triassic lived five major groups of marine reptiles: Pachypleurosauria, Placodontia, Nothosauria, Plesiosauria and Ichthyosauria. Each group is adapted to aquatic life in a very different way and altogether represent an important adaptive radiation to aquatic predators whose origins are probably independent.     Pachypleurosaurs…

Leggi

DO NOT CALL THEM DINOSAURS

   Pterosaurs and dinosaurs belong to the group of Ornithodira, but are classified under two different superorders, the Pterosauromorpha and the Dinosauromorpha. The genetic distance between them is therefore the same as between a bear and a flying lemur. Define pterosaurs “Flying Dinosaurs” is therefore incorrect. The word “pterosaur” means…

Leggi

THE GUIDE FOSSILS

The guide fossils are used for the relative dating of rocks. It is the remains of organisms, which fulfil specific requirements: a wide geographical distribution; a relative abundance of large populations and therefore readily found in sedimentary rocks in the period of their existence; evolved rapidly: thus have a very…

Leggi

TRILOBITES

Trilobites are a group of marine arthropods of small and medium-sized, lived during the Paleozoic Era disappeared completely at the end of the Permian, about 230 million years ago, although their mass extinction occurred at the end of the Devonian.     Trilobites are found in marine deposits of a…

Leggi