A Long-Snouted Predatory Dinosaur from Africa and the Evolution of Spinosaurids

Abstract

Fossils discovered in Lower Cretaceous (Aptian) rocks in the Ténéré Desert of central Niger provide new information about spinosaurids, a peculiar group of piscivorous theropod dinosaurs. The remains, which represent a new genus and species, reveal the extreme elongation and transverse compression of the spinosaurid snout. The postcranial bones include blade-shaped vertebral spines that form a low sail over the hips. Phylogenetic analysis suggests that the enlarged thumb claw and robust forelimb evolved during the Jurassic, before the elongated snout and other fish-eating adaptations in the skull. The close phylogenetic relationship between the new African spinosaurid and Baryonyx from Europe provides evidence of dispersal across the Tethys seaway during the Early Cretaceous.

Mesozoic dinosaurs from Brazil and their biogeographic implications

“…These records are congruent with the already mentioned abundance of spinosaurids in the Cenomanian of North Africa (Fig. 2, 4b) (Russell 1996, Sereno et al 1998, Dal Sasso et al 2005. Carcharodontosaurids are also common in the Aptian to Cenomanian of Africa and South America (Holtz et al 2004, Sereno et al 2004, Novas et al 2005a, Brusatte and Sereno 2007, Casal et al 2009), as well as in older Laurasian deposits (Holtz et al 2004).…”

“…2, 4b-c) (Upchurch et al 2004). Naish et al (2004) suggested the occurrence of some faunal interchange between Europe and South America via Africa in the Early Cretaceous (see also Sereno et al 1998). Indeed, several dinosaur clades recovered in northeastern Brazil in Albian-Cenomanian strata, e.g., Rebbachisauridae, Spinosauridae, Carcharodontosauridae, and Compsognathidae, have older Laurasian records (see above).…”

“…2) has been recorded in the Barremian of Europe (Charig andMilner 1997, Buffetaut 2007) and Early Cretaceous of Thailand and China (Buffetaut andIngavat 1986, Buffetaut et al 2008), but reached its greatest diversity in the Aptian-Cenomanian of northern Africa (Fig. 4b, Stromer 1915, Taquet and Russell 1998, Sereno et al 1998, Buffetaut and Ouaja 2002, Dal Sasso et al 2005, when faunistic similarities with northeastern Brazil are evident. Typical Laurasian theropod clades have been tentatively reported in the Romualdo Member of the Santana Formation.…”

Theropod teeth from the Middle-Upper Jurassic Shishugou Formation of northwest Xinjiang, China

“…The mesial teeth are lanceolate and have a strongly twisted mesial carina and fluted lingual surface (Carrano et al 2002;Hendrickx and Mateus 2014a). In spinosaurids, the mesial and distal serrations are minute or absent, the mesial carina always reaches the cervix, the enamel texture is deeply veined (except in Irritator) and the crowns are subcircular in cross-section and sometimes fluted on one or both lingual and labial surfaces (e.g., Charig and Milner 1997;Sereno et al 1998;Sues et al 2002;Hendrickx and Mateus 2014b).…”

On a pterosaur jaw from the Upper Jurassic of Tendaguru (Tanzania)

“…A few isolated bones have been found at various Cretaceous localities (Swinton 1948, Monteillet et al 1982, Kellner and Mader 1996, Mader and Kellner 1997, 1999, Sereno et al 1998, Martill pers comm. 1999), but only one location, Tendaguru, has yielded Jurassic material.…”