Data from: An ecomorphospace for the Ammonoidea

The fossil conchs of ammonoids provide valuable information about the life
habits of this extinct group. A new conch measurement, the apertural
surface area, is introduced here along with modelled sizes of the buccal
mass and the hyponome, based on ratios of these organs in comparison with
the aperture height from the Recent Nautilus pompilius. A principal
components analysis was performed using the three main characters (1)
apertural surface area index (i.e., the ratio of the apertural surface and
the conch diameter), (2) buccal mass area index (i.e., the ratio between
the buccal mass area and the apertural surface area) and (3) coiling rate
of the conch and reveals an ecomorphospace where life history traits can
be tentatively assigned to species of the Ammonoidea. In this morphospace,
Recent Nautilus has a marginal position, being one of the ectocochleate
cephalopods with best properties for active life (capacity for handling
large food items, rather good mobility). In contrast, most ammonoids
possessed, at comparable conch sizes, much smaller buccal apparatuses and
hyponomes, suggesting a more passive life history with reduced mobility
potential and reduced capacities for larger prey items.