Megalosauridae, Fitzinger, 1843

Monvoisin, Evariste, Allain, Ronan, Buffetaut, Eric & Picot, Laurent, 2022, New data on the theropod diversity from the Middle to Late Jurassic of the Vaches Noires cliffs (Normandy, France), Geodiversitas 44 (12), pp. 385-415 : 408

Indeterminate Megalosauridae

B1, MNHN.F.RJN471, NMH1 are referred to an indeterminate Megalosauridae .

Although it is incomplete, the premaxilla B1 shows important similarities with the megalosaurid Torvosaurus . It is indeed higher than long below the external naris and possess as described by Britt (1991) a snout that slops rearward. Moreover, according to Carrano et al. 2012, an acute snout (inferior to 70°) with an anterior rather than ventral development of the premaxilla relative to the external nares is synapomorphic of Megalosauridae . Thus, the assignment of B1 to this clade seems appropriate. Noteworthy that it differs from Torvosaurus by having four premaxillary teeth instead of three ( Britt 1991). The presence of a close relative of Torvosaurus is supported by the German Callovian megalosaurid Wiehenvenator albati Rauhut, Hübner & Lanser, 2016 which appears to be the sister-taxon of Torvosaurus ( Rauhut et al. 2016) . Torvosaurus is one of the largest Jurassic theropod known. During the Late Jurassic, it is present in North America with Torvosaurus tanneri ( Britt 1991) but also in Europe ( Portugal) with T. gurneyi Hendrickx & Mateus, 2014 . As a result, the palaeobiogeographical and palaeoecological context supports the hypothesis of a torvosaurid relative in the Vaches Noires.

On the distal end of the two femora MNHN.F.RJN471 and NMH1, the absence of a large depression on the anterior surface of the medial condyle is a characteristic of megalosauroids ( Benson 2010; Carrano et al. 2012; Hendrickx & Mateus 2014). Moreover, the remarkable mesiodistal crest in MNHN.F.RJN471 running from the medial condyle to the midline of the distal shaft is similar (although more pronounced here) to Torvosaurus . Thus, it seems appropriate to assign this femur to a Megalosauridae close to Torvosaurus . This femur is a massive bone, indicating a very large theropod. It is probably the largest theropod femur hitherto found in France, as compared with other femoral remains ( Buffetaut 1994b; Buffetaut et al. 1995; Allain 2001, 2005). It is clearly different from the anterior surface of the femur of Streptospondylus, in which a such developed mesiodistal crest is absent, and thus belongs to another taxon. The NMH1 femur described by Buffetaut (1994b) presents a similar thick mesiodistal crest (although it is weaker) and based on this shared feature both specimens are interpreted as belonging to the same taxon. However, MNHN.F.RJN471 is larger so that they indicate two different individuals.