Contribution to the reappraisal of the mid Paleogene ichtyofauna of Western Africa with three new enigmatical elasmobranchs from Thanetian–Lutetian of Senegal

Abstract

We report here three new elasmobranch fossil taxa from Thanetian-Lower Lutetian nearshore marine deposits of northeastern (Matam region) and central-western (Sine-Saloum region) Senegal. These three new taxa represent the oldest species of the enigmatical elasmobranch Odontorhytis, the oldest putative representatives of marine potamotrygonid, and an uncertain dasyatoid genus with the smallest grinding dentition ever described. These new taxa, representing the second Cenozoic elasmobranch remains formally described from Senegal, broaden our understanding of their evolutionary and biogeographic history in the equatorial Eastern Atlantic during this time period. Their occurrences confirm hypothesised stratigraphically correlations between the top of Matam Fm. and the base of Lam Lam Fm., refine the marine connections between these two Senegalese regions, and suggest that these genera were broadly distributed within the shallow marine settings of the equatorial Eastern Atlantic during latest Paleoceneearly Middle Eocene.

Diversity and renewal of tropical elasmobranchs around the Middle Eocene Climatic Optimum (MECO) in North Africa: New data from the lagoonal deposits of Djebel el Kébar, Central Tunisia

“…Abundant in Djebel el Kébar, this species was also recovered from Priabonian deposits of Egypt (BQ, QS, KM), including coastal deposits with fresh water influence in BQ2 (Murray et al, 2010). This genus is likely to be known since the Middle Eocene of West Africa (Sambou et al, 2020) and Pachygymnura attiai nov. gen. was also observed in material from EG (pers. observ.…”

“…The generic attribution to this uncertain shark, only known from the Paleogene (see Cappetta, 2012;Sambou et al, 2020), is noticeable considering its peculiar tooth morphology. Attribution to the Namibian species Odontorhytis pappenheimi is also sustainable, the latter being characterised by the lack of lateral cusplets, a labio-median cutting edge, and by an apico-lingual barb (Case and Cappetta, 1990;Adnet et al, 2011;Cappetta, 2012) even if Case and Cappetta (1990) and Cappetta (2012) noticed that there were probably several species remaining so far undescribed.…”

“…In fact, the distinction of both species is somewhat tenuous, thereby suggesting that both species are present in KEB-1. Alternatively, we suspect that both species illustrate in fact different ontogenetic stages (see also Sambou et al, 2020) of a unique species. We currently retain the attribution to the formal species O. pappenheimi, pending further studies focused on the heterodonty of this peculiar genus.…”

A new Monodontidae (Cetacea, Delphinoidea) from the lower Pliocene of Italy supports a warm-water origin for narwhals and white whales

“…The fossil record of urolophids is poor when compared with the other stingray lineages, possibly because their isolated teeth are often mis-assigned to the wastebasket genus Dasyatis. Beside Arechia crassicaudata other occurrences of the genus are reported from the Ypresian to Lutetian of northern and western Africa (Cappetta, 1983(Cappetta, , 1987(Cappetta, , 2012Cappetta and Traverse, 1988;Noubhani and Cappetta, 1997;Tabuce et al, 2005;Sambou et al, 2017Sambou et al, , 2020, and possibly Mississippi, U.S.A., the Netherlands, and France (Bor, 1985;Cappetta, 2012). Urolophus was reported by Hasse (1882) in the Lutetian of Belgium, and by Noetling (1885) in the Lutetian of Russia, on the basis of vertebral centra.…”