Osteology ofRebbachisaurus garasbaeLavocat, 1954, a diplodocoid (Dinosauria, Sauropoda) from the early Late Cretaceous–aged Kem Kem beds of southeastern Morocco

Abstract

The holotype of the sauropod dinosaur Rebbachisaurus garasbae was discovered in infra-upper Cenomanian horizons of the Kem Kem region of southeastern Morocco in the 1940s and 1950s. The original materials included part of a vertebral column, some of which was found in articulation, and a scapula, a humerus, and an ischium. Of these remains, only the scapula and one of the dorsal vertebrae have been described, but in abbreviated form. Following complete preparation of the partial skeleton, careful examination and fitting of scores of fragments collected with these materials, and computed tomography imaging of the most complete vertebra, we present a complete description of the holotype of Rebbachisaurus garasbae. Our description identifies several autapomorphies of the dorsal and caudal vertebrae, both relating to the shape of the vertebrae and the architecture of their laminae. Based on our reassessment of its anatomy, Rebbachisaurus is recovered as a member of an Afro-European clade that includes Nigersaurus and Demandasaurus. Due to the large size of one of its dorsal vertebrae (ca. 1.45 m tall), Rebbachisaurus has been considered to be a large sauropod. The size of the vertebral centra and the length and cross-sectional area of the humerus of Rebbachisaurus, however, indicate this individual weighed 7915-12,015 kg, which is slightly larger than Amargasaurus but comparable in size to some individuals of Dicraeosaurus. The dorsal vertebrae of Rebbachisaurus and other rebbachisaurids have been suggested to be highly mobile, but results suggest that anatomical features of the vertebrae actually limited rotation and increased resistance to dorsoventrally directed forces applied to the transverse processes.

Taxonomic affinities of the putative titanosaurs from the Late Jurassic Tendaguru Formation of Tanzania: phylogenetic and biogeographic implications for eusauropod dinosaur evolution

“…A fully resolved Nigersaurinae recovers Demandasaurus and the Isle of Wight caudal vertebra as sister taxa, with Tataouinea, Rebbachisaurus, and Nigersaurus as successively more 'basal' nigersaurines. The recovery of Rebbachisaurus within Nigersaurinae prompted Wilson and Allain (2015) to propose that Rebbachisaurinae should replace Nigersaurinae (Whitlock, 2011a), following Article 36 of the International Code of Zoological Nomenclature, which states that: "coordinate nominal taxa of the family group have the same type genus". However, the position of Nigersaurus as the sister taxon of all other members of Nigersaurinae (see also Fanti et al, 2015) means that Nigersaurinae and Rebbachisaurinae do not necessarily have to have the same composition, i.e.…”

A new species of Coloborhynchus (Pterosauria, Ornithocheiridae) from the mid-Cretaceous of North Africa

“…Partial skeletons include a variety of fishes (Cavin et al, 2015), a sauropod dinosaur, Rebbachisaurus garasbae (Lavocat 1954), and the predatory dinosaurs Deltadromeus agilis and Spinosaurus aegyptiacus (Sereno et al, 1996, Ibrahim et al, 2014. A rich and highly diverse vertebrate assemblage is preserved, consisting of freshwater osteichthyans (Cavin and Brito, 2001;Yiabumoto and Uycno, 2005;Forey et al, 2011;Cavin et al, 2015), sharks (Dutheil and Brito, 2009;Martill and Ibrahim, 2012), amphibians (Rage and Dutheil, 2008), turtles (De Broin, 2002;Gaffney et al, 2002Gaffney et al, , 2006, snakes (Klein et al, 2017), crocodyliforms (Larsson and Sues, 2007;Sereno and Larsson, 2009), pterosaurs (Ibrahim et al, 2010;Martill et al, 2018;Rodrigues et al, 2011) and dinosaurs (Sereno et al, 1996;Cau et al, 2012;Ibrahim et al, 2014Ibrahim et al, , 2016Mannion and Barrett, 2013;Wilson and Allain, 2015). In addition, the Kem Kem assemblage also preserves a diverse ichnofauna (Ibrahim et al, 2014), notably rare dinosaur footprints.…”

Peer Review #2 of "How has our knowledge of dinosaur diversity through geologic time changed through research history? (v0.1)"

“…The general patterns of 'global' subsampled diversity shows a steady increase from Middle to the end of Jurassic with a decline through J/K transition Tennant et al 2016b). The relatively high Late Cretaceous subsampled diversity levels can at least be partially explained by the constant discovery of new titanosaurian taxa, especially from Gondwanan continents (Vieira et al 2014;de Jesus Faria et al 2015;Bandeira et al 2016;Poropat et al 2016), and only recently a more appreciated diversity of diplodocoids (e.g., dicraeosaurids, rebbachisaurids) from relatively poorly sampled regions such as Africa (Mannion & Barrett 2013;Wilson & Allain 2015;Ibrahim et al 2016).…”