Late Cretaceous sauropod tooth morphotypes may provide supporting evidence for faunal connections between North Africa and Southern Europe

Femke M Holwerda,Jelle W.F Reumer,Alejandro Blanco,Verónica Díez Díaz,Roel Montie

doi:10.7717/peerj.5925

Abstract

The Cretaceous Kem Kem beds of Morocco and equivalent beds in Algeria have produced a rich fossil assemblage, yielding, amongst others, isolated sauropod teeth, which can be used in species diversity studies. These Albian-Cenomanian (∼113–93.9 Ma) strata rarely yield sauropod body fossils, therefore, isolated teeth can help to elucidate the faunal assemblages from North Africa, and their relations with those of contemporaneous beds and geographically close assemblages. Eighteen isolated sauropod teeth from three localities (Erfoud and Taouz, Morocco, and Algeria) are studied here, to assess whether the teeth can be ascribed to a specific clade, and whether different tooth morphotypes can be found in the samples. Two general morphotypes are found, based on enamel wrinkling and general tooth morphology. Morphotype I, with mainly rugose enamel wrinkling, pronounced carinae, lemon-shaped to (sub)cylindrical cross-section and mesiodistal tapering towards an apical tip, shows affinities to titanosauriforms and titanosaurs. Morphotype II, characterized by more smooth enamel, cylindrical cross-section, rectangular teeth with no apical tapering and both labial and lingual wear facets, shows similarities to rebbachisaurids. Moreover, similarities are found between these northwest African tooth morphotypes, and tooth morphotypes from titanosaurs and rebbachisaurids from both contemporaneous finds from north and central Africa, as well as from the latest Cretaceous (Campanian–Maastrichtian, 83.6 Ma–66.0 Ma) of the Ibero-Armorican Island. These results support previous hypotheses from earlier studies on faunal exchange and continental connections between North Africa and Southern Europe in the Cretaceous.

Highlights

The early Late Cretaceous of northwestern Africa is well-known for its rich vertebrate fauna, many taxa having been described in particular from the Albian–Cenomanian (∼113–93.9 Ma) Kem Kem beds of Morocco, and the Albian–Cenomanian equivalent continental intercalaire of Algeria
Most fossil material consists of isolated elements from theropods and chondrichthyans (e.g., Spinosaurus, Carcharodontosaurus, Onchopristis, Läng et al, 2013; C Underwood, pers. comm., 2018)
The general crown outline is similar in all the teeth of the sample: parallel-sided crowns showing slight labiolingual compression with mesial and distal carinae, which express a higher amount of protrusion in BSPG 1993 IX 331B, BSPG 1993 IX 2A, BSPG 1993 IX 2D, Palaeontological Museum of the University of Zurich (PIMUZ) 0823c and PIMUZ A/III 0823 h

Summary

Introduction

The early Late Cretaceous of northwestern Africa is well-known for its rich vertebrate fauna, many taxa having been described in particular from the Albian–Cenomanian (∼113–93.9 Ma) Kem Kem beds of Morocco, and the Albian–Cenomanian equivalent continental intercalaire of Algeria. The Moroccan Kem Kem beds include aquatic fauna such as sharks, lungfish, coelacanths, bony fish, amphibians, turtles, crocodylomorphs, as well as terrestrial vertebrates such as squamates, pterosaurs, sauropods, and an abundance of theropods (Lavocat, 1954; Russell, 1996; Sereno et al, 1996; Wellnhofer & Buffetaut, 1999; Cavin et al, 2010; Richter, Mudroch & Buckley, 2013; Läng et al, 2013; Mannion & Barrett, 2013) Despite this large diversity, most fossil material consists of isolated elements from theropods and chondrichthyans Studies of sauropod material from this region far found Rebbachisaurus garasbae, and other rebbachisaurids (Lavocat, 1954; De Lapparent & Gorce, 1960; Russell, 1996; Mannion & Barrett, 2013; Wilson & Allain, 2015) as well as several titanosauriform remains, and a possible titanosaurian (De Broin, Grenot & Vernet, 1971; Kellner & Mader, 1997; Mannion & Barrett, 2013; Lamanna & Hasegawa, 2014; Ibrahim et al, 2016). De Lapparent & Gorce (1960) mentioned brachiosaurid finds, these remains are considered to be rebacchisaurid or titanosauriform (Mannion, 2009; Mannion & Barrett, 2013)

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