ceratitid

…the conodonts and many Triassic ceratitid ammonoids became extinct. Only the phylloceratid ammonoids were able to survive, and they gave rise to the explosive radiation of cephalopods later in the Jurassic Period. In addition, many families of brachiopods, gastropods, bivalves, and marine reptiles also became extinct. On land a great

…crisis, but their descendants, the ceratitids, provided the rootstock for an explosive adaptive radiation in the Middle and Late Triassic. Ammonoid shells have a complex suture line where internal partitions join the outer shell wall. Ceratitids have varying external ornamentation, but all share the distinctive ceratitic internal suture line of…