The earliest (Early Cretaceous) record of a vasid gastropod and its importance for understanding the diversification of Neogastropoda

Le résumé fourni par la source

Abstract The emergence of Neogastropoda in the Early Cretaceous and its rapid radiation in the Mid-Cretaceous remain poorly understood due to the extremely limited number of their early fossils. This is why each record from that critically important interval is essential for documenting the early history of the order, as well as for studies utilizing molecular clocks to test hypotheses about evolutionary rates and timing. Here, we describe a new vasid species, Fimbrivasum bulgaricum sp. nov., with a preserved protoconch and a shell morphology with prominent ornamentation and characteristic columellar folds. The specimen also exhibits the earliest occurrences of some functional traits, such as varices and a labral tooth, in Neogastropoda. This finding suggests a much earlier origin of the family Vasidae than previously believed, dating it as the Barremian. It also indicates that neogastropod diversification was well underway in the earliest Cretaceous. We also review the earliest records of living neogastropod superfamilies and their diversification in the Cretaceous showing that the fossil record does not fit well with the molecular phylogeny in the current state of knowledge highlighting the poor fossil record of the group outside of Europe and the United States, and challenges in identification of early members of particular clades.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.