Elasmosaurus pair traverse the open ocean.
A massive marine reptile of the Cretaceous, Elasmosaurus ate fish, and possibly the odd squid to supplement the diet. At 15 metres long, Elasmosaurus was truly the largest of the Plesiosauridae, and indeed one of the most magnificent to behold. With a rosette of very thin and needle-like, sharp conical teeth, Elasmosaurus was a particularly well evolved fish catcher. Like many of its predecessors going back over 130 Million Years before the time of Elasmosaurus, (75-65 MYA) Elasmosaurus had a long and flexible neck, upon which a relatively tiny head fitted. In the murky, algae and nutrient rich waters of the Mesozoic oceans across the world, the small head, would be the only part of the immense reptile visible to a shoal of fish for instance. By the time many fish could realise the head was attached to over 48 feet of predatory Plesiosaur, it would be far too late. With a flex of the neck and snap of the interlocking needle-like teeth, it was all over for many a fish in the Late Cretaceous. What makes Elasmosaurus so special amongst a whole family of marine reptiles adapted for a pescivorous diet, was quite simply the enlarged size of the Elasmosaurus. However, in spite of the size and sheer skill of Elasmosaurus, ultimately, it was the last of a dying breed - Plesiosaurs in general, were declining. After enjoying tens of millions of years alongside the Ichthyosaurs and the Pliosaur branch of the Plesiosaur family, (the short-necked kind) newer, and more well suited animals to the conditions of the Cretaceous, were evolving to replace them. Elasmosaurus was the largest and last of the long-necked Plesiosauria. Giant Mosasaurs became the dominant predators - even Elasmosaurus was not entirely safe from the 17 metre long 'sea serpents' of the Late Cretaceous. Nevertheless, Elasmosaurus remains an important specimen of the Plesiosaur family, exemplifying just how big they could get to the world. Though difficult to estimate, the weight of Elasmosaurus could have been as much as 12-16 tonnes. Elasmosaurus was a large plesiosaur (the largest of the long necked Plesiosaur kind) from the Late Cretaceous Period. Its neck was so long that when it was discovered, it was thought to be the tail, leading American Palaeontologist Edward Drinker Cope to humiliate himself when he published a reconstruction of the great marine reptile with the neck being the tail and the head being on back-to-front on the end of the tail - which is archenemy Othneil Charles Marsh picked up on when he got to handle the specimens himself and realised (much to his amusement at the expense of his great rival of the 'Bone Wars' no doubt) Thanks to Othneil Charles Marsh, we have an accurate reconstruction of the huge 15 metre long Elasmosaurus - last and largest of the Plesiosaurs. There is a similar species of almost the same size as Elasmosaurus called, Thalassomedon, from a slightly earlier part of the Late Cretaceous (the two cousins probably met)