The mid-Ordovician noticed the primary cephalopods with septa solid plenty of to manage Together with the pressures connected with deeper h2o, and could inhabit depths higher than a hundred200 m.[139] The route of shell coiling would demonstrate Squid to be very important to the long run achievement of your lineages; endogastric coiling would only allow big sizing for being attained with a straight shell, Whilst exogastric coiling at first alternatively