Skeletal remains of the oldest known pseudocoracid shark Pseudocorax kindlimanni sp. nov. (Chondrichthyes, Lamniformes) from the Late Cretaceous of Lebanon

Patrick L Jambura,Sebastian Stumpf,Jürgen Kriwet

doi:10.1016/j.cretres.2021.104842

Patrick L Jambura, Sebastian Stumpf + Show 1 more

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https://doi.org/10.1016/j.cretres.2021.104842

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Journal: Cretaceous Research	Publication Date: Apr 4, 2021
Citations: 4	License type: CC BY 4.0

Affiliation: University of Vienna

Abstract

A new fossil mackerel shark, Pseudocorax kindlimanni sp. nov. (Lamniformes, Pseudocoracidae), is described from the Cenomanian Konservat-Lagerstätte of Haqel, Lebanon. The new species is based on the most complete fossil of this group to date, which comprises an associated tooth set of 70 teeth, six articulated vertebral centra, numerous placoid scales and pieces of unidentifiable mineralized cartilage. The dentition of P. kindlimanni sp. nov. is marked by a high degree of monognathic heterodonty but does not exhibit the characteristic “lamnoid tooth pattern” known from other macrophagous lamniform sharks. In addition, P. kindlimanni sp. nov. shows differences in tooth microstructure and vertebral centrum morphology compared to other lamniform sharks. These variations, however, are also known from other members of this order and do not warrant the assignment of Pseudocorax outside the lamniform sharks. The new fossil is the oldest known pseudocoracid shark and pushes the origin of this group back into the Cenomanian, a time when lamniform sharks underwent a major diversification. This radiation resulted not only in high species diversity, but also in the development of a diverse array of morphological traits and adaptation to different ecological niches. Pseudocorax kindlimanni sp. nov. was a small, active predator capable of fast swimming, and it occupied the lower trophic levels of the marine food web in the Late Cretaceous.

Highlights

The Cretaceous represents a fundamental stage for the early evolution and adaptive radiation of numerous marine clades, including marine reptiles (Nicholson et al, 2015), bony fish (Guinot and Cavin, 2016), and elasmobranchs
The holotype specimen of P. kindlimanni sp. nov. represents the most complete fossil of this family to date, as it consists of 70 teeth, six vertebral centra, placoid scales, and pieces of calcified cartilage
In this study we described a new species of Pseudocorax from the Cenomanian of Haqel, Lebanon

Summary

Introduction

The Cretaceous represents a fundamental stage for the early evolution and adaptive radiation of numerous marine clades, including marine reptiles (Nicholson et al, 2015), bony fish (Guinot and Cavin, 2016), and elasmobranchs (sharks and rays; Underwood, 2006; Guinot and Cavin, 2016). Various basal lamniforms occurred during the ValanginianeBarremian Bricen~o et al, 2019) that subsequently experienced a dramatic diversification during the Cenomanian (Underwood, 2006; Guinot, 2013; Guinot and Cavin, 2016), and culminated in lamniform sharks becoming a dominant group during the Cretaceous and Palaeogene. Lamniform diversity declined during the Neogene, and 15 taxa within seven different families occur today (Guinot and Cavin, 2016; Condamine et al, 2019)

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