SHELL-BREAKING PREDATION ON CRETACEOUS SEA URCHINS: SPATIAL AND TEMPORAL PATTERNS

Geographical and temporal patterns of shell-breaking predation on Cretaceous atelostomate sea urchins (Heteraster, Micraster, Echinocorys, Hemipneustes) have been analyzed quantitatively. Evidence of predation comes from predatory bitemarks and regenerated injuries of failed attacks. Especially the holasteroid genus Echinocorys provides an excellent tool of studying predation in space and time: it is a widespread, common and long-ranging genus (Cenomanian to Paleocene), which preserves predatory traces excellently. There is a significant increase of both, predation intensity and diversity of predatory traces from the Late Campanian to the Early Maastrichtian. Investigation of bitemarks using methods developed by forensic odontologists suggest durophaguous sharks (e.g. Heterodontidae, Ginglyostomatidae) as most probable predators. Escape strategies evolved through time include defensive armor (thickening of the test, defensive spines), increase of size and migration into environments where predation intensity is low.