MORPHOLOGICAL DESCRIPTION OF THE EXTINCT NORTH AMERICAN SUCKER, MOXOSTOMA LACERUM, (OSTARIOPHYSI, CATOSTOMIDAE), BASED ON HIGH-RESOLUTION X-RAY COMPUTED TOMOGRAPHY

Abstract

Moxostoma lacerum was the first member of the North American ichthyofauna to be documented as extinct. The oral morphology of the species has been of interest, as it is unusual and unique, as was its diet of small snails. Because of the rarity of specimens, and the disarticulated condition of available skeletons, we take this opportunity to describe the oral skeletal morphology, using the HCTC technology to reconstruct the skeleton digitally. We find that the premaxillary bones lie posteromedial to the maxillae and that maxilla shape is asymmetrical; it is likely that the animal sucked snails from their shells holding the shells with a keratinized mandibular shelf.