A "counterweight mechanism" in Hettangian ammonites?

In most ammonites the siphuncle runs ventrally down the centre of the shell. However, many Hettangian taxa have a siphuncle that is displaced from the midline of the venter accompanied by an asymmetric septal suture line. The ventral lobe is shifted to one side of the whorl where the suture becomes simplified. The ammonites almost became extinct at the end of the Triassic and a single group became the rootstock of the subsequent adaptive radiation. The offset siphuncle is already prevalent in several of the earliest Hettangian genera and by the Late Hettangian, it is widespread throughout two of the three superfamilies. The displacement of the tissue and blood filled siphuncle would have affected the position of the shell’s centre of mass. In order for the ammonite animal to remain vertical in the water column, a "counterweight" system may have been developed. We use computer modeling and data on shell structure to examine this question.