Ophiacodon Mounted specimen on display at the American Museum of Natural History, NYC. Reconstructio

Ophiacodon Mounted specimen on display at the American Museum of Natural History, NYC. Reconstruction by Dmitry Bogdanov When: Late Carboniferous to Early Permian (~305 - 280 million years ago) Where: North America What: Ophiacodon is a basal synapsid, meaning it is more closely related to mammals than modern reptiles. It was a fearsome predator of its day, with a long snout (over half of its skull length) full of pointy teeth. These teeth are so sharp that they are reminicent of the fangs of snakes - the name Ophiacodon means ‘Snake Tooth’. Ophiacodon reached up to 10 feet (~ 3 meters) in length and is thought to have preyed upon its fellow tetrapods rather than insects, as many previous predators focused on.  Ophiacodon occurs very early in synapsid evolutionary history, it is even more basal than the ’sailbacks’; almost at the base of the spilt between the major living aminote clades. Ophiacodon is part of the group Ophiacodontidae, which ranged from Mid Carboniferous to the Early Permian. About a half dozen genera are known for this group, and they all were good sized predators. Ophiacodontids and other basal synapsid clades were once grouped together under the name pelycosaurs, however, this group is not monophyletic/a natural group. That means that some synapsids that were held as pelycosaurs are more closely related to mammals than they are to other 'pelycosaurs’. 'Pelycosaurs’ can be though of as an evolutionary grade in the synapsid lineage; these are the members of our group that more closely resemble reptiles - they had sprawling gaits and their their teeth were not differentiated - there is not even a distinct canine. Ophiacodon and its kin are assuredly synapsids, however, as shown by the single opening behind their eye sockets - their single temporal fenestra.  -- source link

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