Ophiacodontidae (or Ophiacodonts) were pelycosaur synapsids. They appeared in the Late Carboniferous period. Archaeothyris, and Protoclepsydrops, which were oldest synapsids (though Protoclepsydrops being the first synapsid is still unconfirmed because its fossils were fragmentary), were the members of ophiacodontidae, and ophiacodon was a member too. Some ophiacodonts were semi-aquatic, and few were fully aquatic, but some were fully terrestrial like Archaeothyris. They resembled lizards in shape. They have strange, elongated skulls, they also have massive shoulder girdles, probably to provide muscle attachment to support the weight of the huge head. This family is the oldest synapsids and may have been ancestral to all pelycosaurs - which includes therapsids and ultimately mammals. By the Middle Permian, the ophiacodontids were becoming rare, and they were eventually replaced by anomodonts, the diapsid reptiles, and the evolving theriodonts.

External links

• Ophiacondontidae - at Paleos