Reinaut Formation: Platyotocanthus

 The Reinaut Formation in the south of the continent called Guralta is one of, if not the most extensive fossil site from the late Bobossic. Dated to have been formed between 125 and 122 million Eryobian years ago, the Reinaut Formation offers a glimpse of what life was like in the Kikilian, the latest stage of the Bobossic right before the devastating mass extinction dubbed “The World Scarring” happened.
Back when it was formed, the Reinaut Formation was likely a subtropical or temperate open woodland subject to seasonal rains. The fossils discovered in the Reinaut Formation so far, have mostly been megafaunal animals which tended to fossilise better than smaller animals in the conditions that were present in Reinaut 122 million years ago.

Reinaut was filled with incredible creatures that seem both familiar and alien when compared to the modern fauna of Eryobis, but in general they were all animals that one could describe as “typically late Bobossic”. Kampourischiids, Ceratanodires and Saurocheniids were all present in Reinaut as well as the majority of late Bobossic fossil sites around the globe. But Reinaut was also home to an animal that seems completely out of place and time: a Syrinchotid. The very last Syrinchotid in fact, dubbed Platyotocanthus inexpectatus, it was highly derived compared to its ancestors that lived in the Phylloceous some 60 million years earlier. While other Syrinchotids are known from Bobossic deposits, there’s a significant 20 million year gap between Platyotocanthus and the previous youngest known genus, Otocanthula. In addition, P. Inexpectatus highly differs in morphology from other Syrinchotids such as the well studied Dixiphotocanthus brachycorythius from the Gerritsen Formation 176-180 million years ago. Platyotocanthus had short robust legs tipped with very large flat claws. It had a long whip like tail that was lined with small sharp spikes. But what’s the most character of Platyotocanthus was its short sail. Unlike the tail flattened sails of other Syrinchotids, Platyotocanthus had a short sail that curved outwards to form an almost “T” like shape. As with all Syrinchotids, the lateral line organ and thus the ears of these animals were located on top of the sail. The flattened top of the sail of P. Inexpectatus indicates that it a very well developed sense of hearing. This combined with its small eyes, short legs and large claws, has led most researchers to believe it was a fossorial and perhaps nocturnal herbivore that relied mostly on sound to detect threats.