Aristosuchus

The specimen (BMNH R178) now referred to as Aristosuchus pusillus were discovered by Reverend William D. Fox in deposits from the Isle of Wight, specifically from the Wessex Formation (part of the south-western portion of the Wealden Group). BMNH R178 was described in 1876 by Richard Owen, who regarded it as a new species of Poekilopleuron. Poekilopleuron had been named forty years prior by Jacques Amand Eudes-Deslongchamps. Owen, disapproving of how Eudes-Deslongchamps had chosen to spell the genus name, deliberately named his taxon Poikilopleuron pusillus. The species name he gave it, pusillus, originates from the Latin for "very small". Poekilopleuron was at the time believed to be a relative of crocodiles, and Owen saw his taxon in the same way. In 1887, the fossils were revisited by Harry Govier Seeley. Recognising that it differed from Poekilopleuron in key diagnostic features, Seeley opted to give Owen's taxon a new genus name, Aristosuchus. This replacement name comes from the Ancient Greek aristos ("best, superior") and soukhos ("crocodile"). While Seeley loosely supported the idea of Aristosuchus being related to crocodilians, he initially believed that it occupied a taxonomic position between crocodiles and dinosaurs. == Description ==

Aristosuchus was a bipedal, meat-eating (carnivorous) theropod dinosaur. It is thought to have been about in length, The femur of Aristosuchus has a wing-like anterior (front) trochanter and a markedly reduced fourth trochanter. == Classification ==

Since its initial classification as an intermediate between crocodilians and dinosaurs, and many authors followed suit (some regarding C. oweni as a nomen nudum). However, in two papers published in 1999 and 2002, Darren Naish demonstrated that Calamospondylus was based on a different specimen than the Aristosuchus holotype based on letters of correspondence between Richard Owen and Reverend Fox as well as discrepancies in the original description. == Palaeoecology ==

(background), Baryonyx (left), two Neovenator (right), Valdosaurus (midground), and Hypsilophodon'' (foreground). The type specimen of Aristosuchus comes from the Wessex Formation. due to there being more evaporation than precipitation, though precipitation was regardless quite high. The Wessex seems to have regularly experienced extreme storms and periodic flood events, resulting in debris flows which would have deposited dead organisms in ponds. Burned plant and insect material and fusain suggests that the environment experienced frequent wildfires, stifling for the most part the dense growth of gymnosperms. the thyreophorans Polacanthus and the ornithopods Brighstoneus, Comptonatus, Hypsilophodon, Iguanodon, Valdosaurus The pterosaur fauna of the Wessex Formation consists of Coloborhynchus, Caulkicephalus, Istiodactylus, Vectidraco, and Wightia; multiple unnamed pterosaur taxa, including a ctenochasmatid, are also known. and Vectisuchus. Limited evidence exists of elasmosaurids and leptocleidid plesiosaurs. The mammal fauna of the Wessex Formation includes the multituberculate Eobataar and the spalacotheriid Yaverlestes. Albanerpetontid amphibians are represented by Wesserpeton. The fish fauna of the Wessex Formation, both bony and cartilaginous, is extensive, including hybodontiform and modern sharks (Selachii), pycnodontiforms, Lepidotes and Scheenstia. Invertebrates are represented by an assortment of non-biting midges, hymenopterans (wasps) including multiple parasitoid taxa, coleopterans (beetles), the avicularoid spider Cretamygale, and the ostracod Cypridea''. == References ==