Attempted predation on Early Paleozoic cornulitids

Cornulitids appeared in the Middle Ordovician, and the earliest repairs to their shells are reported from the Upper Ordovician (Katian) of Baltica and North America (Hirnantian). Shell repair is common in the Silurian (Sheinwoodian) unattached cornulitid Cornulites cellulosus from the Baltica and is interpreted here as a result of failed predation. Scalloped, divoted and embayed type of shell repairs occur in three species of Cornulites. The species with the most repairs, C. cellulosus, yielded a shell repair frequency of 20.7% with 29 specimens. There are probable antipredatory adaptations, such as spines and extremely thick vesicular walls, in the morphology of Silurian cornulitids. The morphological and ecological evolution of cornulitids could thus have been partially driven by predation.