A new pliosaur; Makhaira rossica has been discovered in western Russia with unique teeth similar to an ancient crocodile, the species adds to knowledge on the diversity and ecology of these animals. How this species relates to crocodylomorphs has also been illuminated.
The Mesozoic period hosted some of the largest animals to ever live in the oceans. The pliosaur was one of these, a large carnivorous marine reptile of the plesiosauria order. These animals fed on fish, small sea dinosaurs and marine reptiles like the ichthyosaur, which were also very large measuring up to 23 metres long and compared to modern whales or dolphins. The pliosaurs mainly lived in the ancient seas which are now mainland Europe although other fossils have been found in South America, Australia and the Arctic.
These pliosaur fossils suggest the group shared evolutionary success due to its diversity and a unique adaptability in relation to feeding strategies. With large fins to propel it, thought to provide excellent acceleration used in ambush situations, a large head, similar in shape to the closely related crocodile, a short neck and also unique teeth giving clues into the prey a particular species favoured. The group known as sauropterygia includes pliosaurs which lived from the Triassic to the end of the cretaceous and are believed to be the longest living marine tetrapod’s (animals with four legs). Being at the top of the food chain these species were considered to be an apex predator.
The discovery of a new pliosaur from the banks of the Volga river in western Russia by Valentin Fischer from the University of Oxford and an international team, gave it the name “Makhaira rossica”. This word makhaira means “blade with a curved outline” and the latin rossica means “Russian”. This new species is slightly smaller than most pliosaurs unearthed, it has unique teeth which possess alveoli (sockets in the jaws in which roots of the teeth are held), are trihedral in structure, consist of finely serrated carinae and are large.
The teeth suggest this pliosaur used a form of feeding known as macrophagy; the feeding on large organisms similar to the strategies used by ancient crocodiles. The animal may have modified this distinct feature convergent with the macrophagous archosaurs or sphenacodontoids. In this respect Makhaira rossica differs to other pliosaurs, as morphological features suggest other species had a diet consisting of smaller prey. This different approach has been demonstrated by the fossils of conical and uniform teeth, lacking carinae (serrations), proportional elongation of the snout and reduction in the size and length of other anatomical characteristics. As very little is known about the pliosaurids where only two partial skeletons have been found, the Makhaira rossica may elucidate further the diversity and ecology of pliosaurids. The finding of Makhaira rossica divides the long branch leading to brachauchenines with which it shares many common traits.
The serrated teeth of Makhaira rossica imply it is closely related to metriorhynchoid crocodylomorphs, although clear connections other than this are far from evident. The team placed the animal’s phylogenetic position as the most basal member of the brachauchenines and which lived in the Hauterivian Period of the cretaceous between 133 and 129.4 million years ago. Recent studies found evidence of the youngest metriorhynchoid fossil known, which extends the duration of this species by several millions of years and details which distinguish between this species teeth and Makhaira rossica’s are almost absent.
Makhaira rossica has added to a wealth of knowledge on pliosaurs, with its relation to crocodyloforms also coming to light, how this species occupies its own unique clade is fascinating and curiosity may further illuminate these questions. These species have attained great interest as a result of films like Jurassic World, subsequently this may stimulate further interest in palaeontology and raise the chance of potential future discoveries.
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