DEATH BY COMMON HOUSEHOLD TOOLS: MECHANICAL ANALOGY AND THE FUNCTIONAL MORPHOLOGY OF THE HYPOSTOME IN GENUS ISOTELUS (DEKAY) EVIDENCE FROM ISOTELUS IOWENSIS (OWEN)
Isotelid species including I. maximus, I. gigas, I. rex and I. iowensis all attain a relatively large size compared to other trilobites. This relates to food intake that had high nutritional value. A number of specimens of I. iowensis have been found in association with Chondrites isp. burrows. In the Maquoketa Shale, a distal tempestite bed containing anoxic mud (now pyritic shale) yields trilobites “frozen” in time. They appear to have been feeding at the level of an abundance of Chondrites isp.burrows.
The forked shape of the isotelid hypostome was an adaptation for infaunal polychete worm extraction. The flattened shovel-like cephalon was well adapted for digging into soft sediment. The morphological fits between common household tools i.e. claw hammer and spade and the hypostome and cephalon in the Genus Isotelus is remarkable. This strategy made the isotelids highly successful as predators on and in muddy infaunal environments.