Pliosaur tooth, giant marine reptile Troodon Crinoids are animals despite their

Crinoids are animals despite their plant-like appearance

This large enrolled trilobite is from the Devonian of the Alnif region of Morocco

Edward Hitchcock

The density of specimens in the Aspidella beds suggests levels of benthic biomass in the Neoproterozoic that could rival those of modern marine communities

Pliosaur tooth, giant marine reptile Troodon Crinoids are animals despite theirPLIOSAURUS(pronounced PLY oh SAWR us) Pliosaurus (meaning "greater lizard") was a huge, short necked plesiosaur that lived during the middle to late Jurassic period. This carnivore was a flippered marine reptile (a pliosaur and a plesiosaur, but not a dinosaur) with many sharp teeth in large, powerful jaws resembling those of a crocodile; the teeth were three sided in cross section. It was 33 40 ft (10 12 m) long and the skull was 5 6. 6 ft (1. 5 2 m)