Dental Morphology, Palaeoecology and Palaeobiogeographic Significance of a New Species of Requiem Shark (Genus <i>Carcharhinus</i>) from the Lower Miocene of Peru (East Pisco Basin, Chilcatay Formation)

• Published in: Journal of Marine Science and Engineering
• Main Authors: Alberto Collareta, René Kindlimann, Alessio Baglioni, Walter Landini, Giovanni Sarti, Alí Altamirano, Mario Urbina, Giovanni Bianucci
• Format: Article
• Language: English
• Published: MDPI AG 2022-10-01
• Subjects: Burdigalian; Carcharhinidae; Carcharhiniformes; <i>Carcharhinus dicelmai</i> sp. nov.; Central American Seaway; clutching-type dentition
• Online Access: https://www.mdpi.com/2077-1312/10/10/1466

Nowadays, the requiem sharks comprise one of the most diverse and widespread families of selachians, i.e., Carcharhinidae. Among the carcharhinids, the genus <i>Carcharhinus</i> has the largest number of living species, namely, at least 35. Known from fossils as old as the Cretaceous, the requiem sharks did not significantly radiate before the Eocene (when <i>Carcharhinus</i> also appeared), and their diversification mainly occurred in Neogene times. Here, we describe a new species of requiem shark, <i>Carcharhinus dicelmai</i> sp. nov., based on fossil teeth from Lower Miocene (18.4–18.1 Ma) strata of the Chilcatay Formation of the East Pisco Basin (southern Peru). Upper teeth of <i>C. dicelmai</i> sp. nov. are typically provided with a slender, smooth-edged cusp; a marked coronal twist; and a distal heel that bears 1–5 coarse, angularly lobate serrae that become more prominent toward the base of the cusp. The dentition of <i>C. dicelmai</i> sp. nov. appears less akin to that of most other carcharhines to the cutting-clutching type, and seemingly testifies to the development of more predominantly clutching adaptations. A carcharhinid tooth from the Burdigalian to lower Langhian Cantaure Formation of Venezuela is reassigned to <i>C. dicelmai</i> sp. nov., suggesting a trans-Panamanian distribution for this extinct shark species.