The mid-Ordovician saw the main cephalopods with septa strong enough to manage Along with the pressures linked to deeper h2o, and will inhabit depths higher than a hundred200 m.[139] The course of shell coiling would demonstrate to become very important to the long run good results of the lineages; endogastric coiling would only allow big sizing to get attained having here a straight shell, Whilst exogastric coiling at first alternatively