In Depth Discovered in New Zealand, Mauisaurus was for a long time credited as one of the largest plesiosaurs. However in more recent times there have been doubts about the validity of fossils attributed to the genus since these have come from so many different locations. Mauisaurus also displays the long sharp teeth often seen … Read more
In Depth Thalassomedon is regarded as a mid-sized elasmosaurid plesiosaur, especially when compared with larger genera like Mauisaurus. The distribution of Thalassomedon remains show that it swam in the Western Interior Seaway, a Cretaceous sea that divided North America into two halves. Thalassomedon is so far only known from the early stages of the Late … Read more
In Depth Fresnosaurus was a late Cretaceous era elasmosaurid plesiosaur that seems to have the signature feature of this group of a very long neck proportionately greater than in earlier and more primitive plesiosaur forms. Like with these other genera, Fresnosaurus was probably a specialist hunter of fish and soft bodied cephalopods like squid. Fresnosaurus … Read more
In Depth Albertonectes is one of the best preserved elasmosaurid plesiosaurs to be discovered in Canada, and has a total of 76 cervical (neck) vertebrae . Elasmosaurid pesiosaurs like Albertonectes are noted for having their long necks that are proportionately much longer than earlier plesiosaur types. This would have been a specialist feeding adaptation allowing … Read more
In Depth Described from a single partially preserved skull, Alexandronectes was an elasmosaurid plesiosaur that swam in the waters around what is now New Zealand during the late Cretaceous. These were dangerous waters as fossils of large mosasaurs such as Taniwhasaurus are also known from the same formation as Alexandronectes, and these predators were certainly … Read more
In Depth The original 2012 paper of the plesiosaur Spitrasaurus included the description of not one but two species for the genus. The type species, S. wensaasi (PMO 219 718) is described from sixty articulated cervical vertebrae believed to have come from a juvenile individual. S. larseni (SVB 1450) is also known from cervical vertebrae, … Read more
In Depth Edgarosaurus seems to have been one of the first polycoylid plesiosaurs to swim in the late Cretaceous Western Interior Seaway, a shallow sea that submerged much of central North American during the Cretaceous. Like its relatives, Edgarosaurus had a typical plesiosaur body but a short neck an elongated jaws, features reminiscent of the … Read more
In Depth The type specimen of Megacephalosaurus was originally assigned to the Brachauchenius genus, leading to the idea that Brachauchenius was one of the biggest of its time. The removal of this skull has led to a size revision of Brachauchenius, and the establishment of a new genus, Megacephalosaurus. However this still means that there … Read more
In Depth Named after the legendary island of Avalon (and supposed resting place of King Arthur), Avalonnectes was a rhomaleosaurid plesiosaur. Aside from being related to the type genus of the group, Rhomaleosaurus, this meant that Avalonnectes is noted as being a genus of shorter necked plesiosaurs. Avalonnectes has been considered to be a more … Read more
In Depth Acostasaurus is a genus of pliosaur that lived during the early Cretaceous period. Acostasaurus was a small to middle sized pliosaur that seems to have differed from brachauchenisine pliosaur that were otherwise common at the time and location. This could suggest that Acostasaurus had a different lifestyle/feeding preference to other larger pliosaurs. Further … Read more