New plesiosaurian specimens (Reptilia, Plesiosauria) from the Upper Cretaceous (Turonian) of Goulmima (Southern Morocco)
Introduction
Plesiosaurians are extinct predatory marine reptiles that represent one of the longest-ranging groups of Mesozoic marine reptiles, extending stratigraphically from the Upper Triassic to the uppermost Cretaceous (Vincent et al., 2011, Benson et al., 2012). During the Late Cretaceous, they achieved a worldwide distribution, including high-latitude seas surrounding Antarctica (e.g., Gasparini et al., 2003, Vandermark et al., 2006, Novas et al., 2015, Sachs et al., 2015). Compared to in other continents, the fossil record of plesiosaurians is scarce in Africa where only seven valid taxa are known (see Vincent et al., 2011, Vincent et al., 2013, Allemand et al., 2017).
The Turonian deposits (Upper Cretaceous) of the Goulmima area, in the Southern slope of the High Atlas (see Fig. 1A), have yielded a diverse marine fauna including ammonites, chondrichthyans (Underwood et al., 2009), bony fishes (Cavin, 1995, Cavin, 1997, Cavin, 1999, Cavin, 2001, Cavin et al., 2001, Cavin et al., 2010) and large marine reptiles, such as a turtle, the basal mosasauroid Tethysaurus nopcsai Bardet et al., 2003a (Bardet et al., 2003a, Bardet et al., 2008) and three major families of Cretaceous plesiosaurians (Angst and Bardet, 2015). The Elasmosauridae are represented by Libonectes morgani (Carpenter, 1997), the Polycotylidae by Thililua longicollis Bardet, Pereda Suberbiola and Jalil, 2003b and Manemergus anguirostris Buchy, Métayer and Frey, 2005, and the Pliosauridae by Brachauchenius lucasi Williston, 1903 (Bardet et al., 2003b, Buchy, 2005, Buchy et al., 2005, Angst and Bardet, 2015, Sachs and Kear, 2017, Allemand et al., 2017). The taphonomical preservation in Goulmima is particular in that fossils are contained in one or several ovoid calcareous nodules (Cavin et al., 2010), in which the siliceous material prevents complete preparation of the specimens and fossilized bones in the nodules are often completely dissolved, making their extraction from the host rock and their study difficult or impossible. This preservation can often prevent a complete access to the fossil anatomy and the use of computed microtomography represents a suitable solution to circumvent these technical issues.
The present study examines two new plesiosaurian specimens (D1-8213 and MNHN F-GOU14) from the area of Goulmima in Southern Morocco (Fig. 1). Although their exact location remains unknown, the calcareous matrix surrounding the specimens is nevertheless consistent with the vertebrate-bearing nodules known from the Unit T2a of the Akrabou Formation (Ettachfini and Andreu, 2004). These nodules are concentrated near the top of a Cenomanian-Turonian calcareous succession and considered as early Turonian in age based on the ammonite assemblage (mainly Mammites) (Cavin, 1995, Cavin, 1997, Cavin, 1999, Cavin, 2001, Cavin et al., 2001, Cavin et al., 2010, Bardet et al., 2003a, Bardet et al., 2003b, Ettachfini and Andreu, 2004, Buchy, 2005, Buchy et al., 2005, Kennedy et al., 2008, Allemand et al., 2017). Both specimens are preserved in incompletely prepared nodules and we used X-ray computed microtomography in order to reveal anatomical details that are not otherwise directly observable.
D, Musée de Rhinopolis, Gannat, France; MNHN, Muséum National d'Histoire Naturelle, Paris, France; NHMUK, Natural History Museum, London, UK; ROM, Royal Ontario Museum, Toronto, Ontario, Canada; SGU, Saratov State University, Saratov, Russia; SMNK, Staatliches Museum für Naturkunde Karlsruhe, Germany; SMNS, Staatliches Museum für Naturkunde, Stuttgart, Germany; SMU SMP, Shuler Museum of Paleontology, Southern Methodist University, Dallas, U. S. A.
Section snippets
Material and method
The two specimens, MNHN F-GOU14 and D1-8213 (Fig. 2), are respectively housed in the Muséum National d'Histoire Naturelle (Paris, France) and the Rhinopolis Museum (Gannat, France) collections. These two specimens are preserved in a nodule in two pieces that fit perfectly. The complete nodules enclosing MNHN F-GOU14 and D1-8213 measure 36, 12, 11 and 41, 15, 12 cm long, wide and high respectively. The specimens are incompletely prepared. In both cases, the anterior half of the nodule shows
Systematic palaeontology
SAUROPTERYGIA Owen, 1860
Order PLESIOSAURIA de Blainville, 1835
Super Family PLESIOSAUROIDEA Welles, 1943 (sensu Ketchum and Benson, 2010)
Family ELASMOSAURIDAE Cope, 1869
Genus LIBONECTES Carpenter, 1997
Type species: ELASMOSAURUS MORGANI Welles, 1949
Synonym. Libonectes atlasense Buchy, 2005 (sensu Sachs and Kear, 2017).
Holotype. SMU SMP 69120, skull and mandible, atlas-axis complex, 48 successive cervical vertebrae, fragmentary thoracic ribs, gastralia and associated gastroliths (Welles, 1949,
Diagnostic features and paleobiological implications
According to Sato et al. (2011), it is usually difficult in plesiosaurians to determine whether a particular feature of the braincase is diagnostic to a species or shared within a higher taxonomic rank because of the difficulties to access this region. Here, the description of two plesiosaurian specimens provides additional knowledge about their braincases. We considered their variability and, as in the study performed by Sato et al. (2011), to focus on their potential phylogenetic signal and
Conclusion
The plesiosaurian braincase is a part of the skull poorly known due to either poor preservation and/or insufficient preparation. Here, the use of computed microtomography provides new anatomical information about the braincase and the palate of two Moroccan plesiosaurian specimens difficult to study by direct observation because of their particular mode of preservation. This contribution emphasizes the importance to have access and consider these regions in order to identify plesiosaurian taxa,
Acknowledgments
This work was supported by a grant from the Agence Nationale de la Recherche under the LabEx ANR-10-LABX-0003-BCDiv, in the program “Investissements d'avenir” ANR-11-IDEX-0004-02. We are grateful to the Rhinopolis Museum for the loan of the specimen D1-8213. We thank the AST-RX platform at the MNHN for access to the CT-scan, M. Garcia Sanz (MNHN, UMS 2700 OMSI) for producing the CT scans and F. Goussard (MNHN, UMR 7207 CR2P) for assistance with 3D digital reconstructions and imaging based on CT
References (84)
- et al.
A new mosasauroid (Squamata) from the Late Cretaceous (Turonian) of Morocco
Comptes Rendus Palevol
(2003) - et al.
A new polycotylid plesiosaur from the Late Cretaceous (Turonian) of Morocco
Comptes Rendus Palevol
(2003) Comparative cranial anatomy of two North American Cretaceous plesiosaurs
Osteology and phylogenetic relationships of the teleost Goulmimichthys arambourgi Cavin, 1995 from the Upper Cretaceous of Goulmima, Morocco
Eclogae Geologicae Helvetica
(2001)- et al.
L'évolution paléoenvironnementale des faunes de poissons du Crétacé supérieur du bassin du Tafilalt et des régions avoisinantes (Sud-Est du Maroc): implications paléobiogéographiques
Compte Rendu de l'Académie des Sciences de Paris, Sciences de la Terre et des planètes
(2001) - et al.
Vertebrate assemblages from the early Late Cretaceous of southeastern Morocco: an overview
Journal of African Earth Sciences
(2010) - et al.
Le Cénomanien et le Turonien de la plate-forme Préafricaine du Maroc
Cretaceous Research
(2004) - et al.
First record of Polycotylidae (Sauropterygia, plesiosauria) from the Upper Cretaceous of Antarctica
Cretaceous Research
(2015) - et al.
Redescription of Tuarangisaurus keyesi (Sauropterygia; Elasmosauridae), a key species from the Uppermost Cretaceous of the Weddellian province: internal skull anatomy and phylogenetic position
Cretaceous Research
(2017) - et al.
Le premier squelette de Plesiosaure de France sur le Causse du Larzac (Toarcien, Jurassique inférieur)
Géobios
(1990)
Morphological and taxonomic clarification of the genus Plesiosaurus
Zarafasaura oceanis, a new elasmosaurid (Reptilia: Sauropterygia) from the Maastrichtian Phosphates of Morocco and the palaeobiogeography of latest Cretaceous plesiosaurs
Gondwana Research
New plesiosaur specimens from the Maastrichtian Phosphates of Morocco and their implications for the ecology of the latest Cretaceous marine apex predators
Gondwana Research
Plesiosaurs from the Upper Cretaceous (Cenomanian–Turonian) tropic shale of southern Utah, part 2: polycotylidae
Journal of Vertebrate Paleontology
Virtual re-examination of a plesiosaurian specimen (Reptilia, Plesiosauria) from the Late Cretaceous (Turonian) of Goulmima (Southern Morocco) thanks to computed tomography
Journal of Vertebrate Paleontology
A Descriptive Catalogue of the Marine Reptiles of the Oxford Clay. Based on the Leeds Collection in British Museum (Natural History), Part II
A new record of the pliosaur Brachauchenius lucasi Williston, 1903 (Reptilia: Sauropterygia) of Turonian (Late Cretaceous) age, Morocco
Geological Magazine
A new elasmosaurid plesiosaur from the Lower Jurassic of Southern France
Palaeontology
The Cenomanian–Turonian (Late Cretaceous) radiation of marine squamates (Reptilia): the role of the Mediterranean Tethys
Bulletin de la Société Géologique de France
Cranial anatomy of Thalassiodracon hawkinsii (Reptilia, Plesiosauria) from the Early Jurassic of Somerset, United Kingdom
Journal of Vertebrate Paleontology
High diversity, low disparity and small body size in Plesiosaurs (Reptilia, Sauropterygia) from the Triassic–Jurassic boundary
PLoS ONE
A new leptocleidid (Sauropterygia, Plesiosauria) from the Vectis Formation (Early Barremian–early Aptian; Early Cretaceous) of the Isle of Wight and the evolution of Leptocleididae, a controversial clade
Journal of Systematic Palaeontology
Description de quelques espèces de reptiles de la Californie, précédée de l'analyse d'un système général d'Erpétologie et d'Amphibiologie
Nouvelles Annales du Muséum (national) d'Histoire Naturelle de Paris
A taxonomic reappraisal of the families Elasmosauridae and Cryptoclididae (Reptilia: Plesiosauria)
Revue de Paléobiologie
Osteological redescription of the skull of Microcleidus homalospondylus (Sauropterygia, Plesiosauria) from the Lower Jurassic of England
Journal of Paleontology
An Elasmosaur (Reptilia: Sauropterygia) from the Turonian (Upper Cretaceous) of Morocco
Carolinea
Osteology of Manemergus anguirostris n. gen. et sp., a new plesiosaur (Reptilia, Sauropterygia) from the Upper Cretaceous of Morocco
Palaeontographica, Abteilung A
Goulmimichthys arambourgi n. g., n. sp., un Pachyrhizodontidae (Actinopterygii, Teleostei) d'une nouvelle localité a nodules fossilifères du Turonien inferieur marocain
Comptes Rendus de l'Académie des Sciences, Paris, Série IIa
Nouveaux Teleostei du gisement du Turonien inférieur de Goulmima (Maroc)
Compte Rendus de l'Académie des Sciences de Paris
Occurrence of a juvenile teleost, Enchodus sp., in a fish gut content from the Upper Cretaceous of Goulmima, Morocco
Palaeontology
Synopsis of the extinct Batrachia and Reptilia of North America
Transactions of the North American Philosophical Society
A Lower Cretaceous pliosauroid from South Africa
Annals of the South African Museum
A new marine reptile (Sauropterygia) from New Zealand: further evidence for a Late Cretaceous austral radiation of cryptoclidid plesiosaurs
Palaeontology
Osteology of a new plesiosaur from the Lower Cretaceous (Albian) Thermopolis Shale of Montana
Journal of Vertebrate Paleontology
Skeletal anatomy of an exceptionally complete specimen of a new genus of plesiosaur from the Early Cretaceous (Early Albian) of northeastern Alberta, Canada
Palaeontographica Abteilung A
A phylogeny of Plesiosauria (Sauropterygia) and its bearing on the systematic status of Leptocleidus Andrews, 1922
Zootaxa
A New Genus of Plesiosaur (Reptilia: Sauropterygia) from the Pliensbachian (Early Jurassic) of England, and a Phylogeny of the Plesiosauria
The elasmosaurid plesiosaur Aristonectes Cabrera from the latest Cretaceous of South America and Antarctica
Journal of Vertebrate Paleontology
Preliminary description and phylogenetic position of a new plesiosaur (Reptilia: Sauropterygia) from the Toarcian of Holzmaden, Germany
Journal of Paleontology
Biogeographic and biostratigraphic implications of Australian Mesozoic marine reptiles
Australian Biologist
A new elasmosaurid plesiosaur from the Lower Cretaceous of Queensland, Australia
Journal of Vertebrate Paleontology
Reassessment of the Lower Cretaceous (Barremian) pliosauroid Leptocleidus superstes Andrews, 1922 and other plesiosaur remains from the nonmarine Wealden succession of southern England
Zoological Journal of the Linnean Society
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A new cuspidate ptychodontid shark (Chondrichthyes; Elasmobranchii), from the Upper Cretaceous of Morocco with comments on tooth functionalities and replacement patterns
2022, Journal of African Earth SciencesCitation Excerpt :The Akrabou Formation also includes marly limestones, marls, and other impure micrites with ovoid calcareous concretions (see “Asfla Member” in Fig. 2B) testifying to middle to outer ramp early Turonian marine environment (e.g. Lézin et al., 2012; Meister et al., 2017; Villalobos-Segura et al., 2019; Cooper and Martill, 2020; Veysey et al., 2020). Local people commonly excavate various localities in the Goulmima area (e.g. the villages of Tadirhoust and Asfla; see white asterisk in Fig. 2), searching for macrofossils, such as exceptionally preserved vertebrate remains usually embedded in calcareous nodules (e.g. Bardet et al., 2003a, b; Cavin et al., 2010; Claeson et al., 2013; Angst and Bardet, 2015; Allemand et al., 2018; Cooper and Martill, 2020; Villalobos-Segura et al., 2021). In particular, a sequence of alternating facies succession consisting of fossiliferous packstones, chalky marls, cherts and vertebrate-bearing nodular horizons belonging to the Asfla Member (Fig. 2B) of the Akrabou Fm of the Asfla area are targeted for vertebrate fossils (e.g. Cavin et al., 2010; Claeson et al., 2013; Angst and Bardet, 2015; Villalobos-Segura et al., 2019; Cooper and Martill, 2020).
Late Cretaceous marine reptiles from Malyy Prolom in Ryazan Oblast, Central Russia
2021, Cretaceous ResearchCitation Excerpt :However, the putative account of ‘Polpytychodon patagonicus’ Ameghino, 1893 from the southern Atlantic margin of Argentina (see Madzia, 2016) has been reinterpreted as an indeterminate plesiosaurian (O'Gorman and Varela, 2010). Like brachauchenine pliosaurids, elasmosaurids and polycotylids were geographically ubiquitous Late Cretaceous plesiosaurian clades, but with numerous Cenomanian–Turonian records (including trans-Atlantic species ranges, e.g., Libonectes morgani: Sachs and Kear, 2017) from European Russia to Western Europe (e.g., Persson, 1963; Milner, 1987; Bardet and Godefroit, 1995; Storrs et al., 2000; Kear et al., 2014; Sachs et al., 2016, 2017, 2018), North Africa (e.g., Bardet et al., 2003a; Allemand et al., 2017; Sachs and Kear, 2017; Allemand et al., 2018; Fischer et al., 2018; Allemand et al., 2019), and North America (e.g., Carpenter, 1996, 1997, 1999; Storrs, 1999; Sachs and Kear, 2015; Sachs et al., 2021). Similarly, Late Cretaceous ophthalmosaurid ichthyosaurians were globally distributed, and apparently diversified within the epicontinental seas covering what is now the Russian Platform prior to their final extinction at the end of the Cenomanian (Fischer et al., 2016).
The most complete specimen of Kawanectes lafquenianum (Sauropterygia, Plesiosauria): New data on basicranial anatomy and possible sexual dimorphism in elasmosaurids
2021, Cretaceous ResearchCitation Excerpt :and SGU 251/1 (Zverkov et al., 2018). In some cases the presence of the posterior interpterygoid symphysis precludes direct observation of the posterior limit of the parasphenoid as in Callawayasaurus colombiensis and Libonectes morgani, however in the two mentioned species the parasphenoid reaches at least the anterior margin of the posterior pterygoid symphysis (Welles, 1962; Carpenter, 1997; Allemand et al., 2017, 2018). The parasphenoid shows a ventral keel in K. lafquenianum, as in Callawayasaurus colombiensis, Libonectes morgani, Tuarangisaurus keyesi and Aristonectes quiriquinensis Otero, Soto-Acuña, O'Keefe, O'Gorman, Stinnesbeck, Suárez, Rubilar-Rogers, Salazar, Quinzio-Sinn, 2014 and the SGU 251/1 (Welles, 1962; Wiffen and Moisley, 1986; Carpenter, 1997; O'Gorman et al., 2017; Sachs et al., 2017; Allemand et al., 2017, 2018; Otero et al., 2018; Zverkov et al., 2018).