Plesiosauria

These are the sea reptiles famously likened to snakes being threaded through turtles. They are the long-necked plesiosaurs. Plesiosaurs appeared in the Late Triassic-Early Jurassic, and had become highly successful towards the end of the Jurassic. Though small (a ‘only’ a 10 foot long maximum to begin with) soon enough, 8 metre long fish catchers were hunting the seas of the Jurassic Towards the end of the Cretaceous Period, the Plesiosaurs on a whole, began to decline. However, the few remaining species took on special roles in the ecosystem, and often grew into comparative giants. Elasmosaurus were over 15 metres (49 feet) long, 8 metres (24 feet) across and over 12-16 tonnes in weight. Plesiosaurs were the long-lasting contemporaries of the Ichthyosaurs, the Pliosaurs (Pliosaurs themselves being the short-necked descendents of some of the early Plesiosaurs) and eventually the Mosasaurs. Throughout their long time on Earth, the basic design of the Plesiosaurs barely changed, though the size proportions of some of the last Plesiosaurs were noticeably different, being larger. As well as maintaining an almost unchanging shape, they had pretty much the same kind of diet, from the beginning to the end – Fish. Lots of Fish. Perhaps the odd squid, but perhaps not even that. Fish, and the fossil record shows that the Plesiosaurs could tackle any Fish that they fit inside their heads. This means that the large Fish were safe from them, and that the small Fish were the mainstay of the Plesiosaur diet. It is thought that the small head (and very long-neck to stretch it there) of the Plesiosaurs, allowed them to fool the Fish into thinking that the small head was the full animal, as the massive body was hidden in the murk behind it. When the small Fish realised that there was what could have been another 48 feet of carnivorous reptile attached, it would already be on its way down the Plesiosaur’ throat. Plesiosaurs, were the Mesozoic Sea-Dragons of Victorian legend.