New dinosaurs link southern landmasses in the Mid–Cretaceous

Abstract

Abelisauroid predators have been recorded almost exclusively from South America, India and Madagascar, a distribution thought to document persistent land connections exclusive of Africa. Here, we report fossils from three stratigraphic levels in the Cretaceous of Niger that provide definitive evidence that abelisauroid dinosaurs and their immediate antecedents were also present on Africa. The fossils include an immediate abelisauroid antecedent of Early Cretaceous age (ca. 130-110 Myr ago), early members of the two abelisauroid subgroups (Noasauridae, Abelisauridae) of Mid-Cretaceous age (ca. 110 Myr ago) and a hornless abelisaurid skull of early Late Cretaceous age (ca. 95 Myr ago). Together, these fossils fill in the early history of the abelisauroid radiation and provide key evidence for continued faunal exchange among Gondwanan landmasses until the end of the Early Cretaceous (ca. 100 Myr ago).

Neovenatorid theropods are apex predators in the Late Cretaceous of North America

“…North American mid-Cretaceous assemblages represent a transition between these extremes in that they are currently characterized by low diversity (although this may be related to sampling bias) and low to moderate endemism, with sister taxa occurring on at least two other continents 41 . A similar pattern is also evident in abelisaurid 38 and spinosaurid 42 theropods. Such low levels of theropod endemicity are closer to those observed in Early Jurassic Pangaean theropod faunas, than to the more taxonomically depauperate latest Cretaceous faunas.…”

Mesozoic dinosaurs from Brazil and their biogeographic implications

“…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). …”

“…Taxa from a variety of dinosaur clades have been recorded in the Triassic strata of the Santa Maria and Caturrita formations (Langer et al 2007a), the mid-Cretaceous of the Araripe and São Luís-Grajaú basins (Frey and Martill 1995, Kellner 1996a, b, 1999, Medeiros et al 2007, and the Late Cretaceous of Bauru endemic range, upon which all paleobiogeographic hypotheses are erected. In this paper, we provide a reevaluation of the Brazilian dinosaur record from Triassic to Cretaceous ages based primarily on body-fossils, and discuss their relevance in the light of recent hypotheses dealing with dinosaur biogeography in the Mesozoic (Upchurch et al 2002, Sereno et al 2004, Krause et al 2006, Nesbitt et al 2009). …”

A new genus of dipnoiformes from the Cretaceous of Brazil

“…Although the similarities observed in the recorded transatlantic faunal elements are obviously resultant of the major vicariant event that separated Gondwanan landmasses, the presence of dinosaur genera common to the continents of either side of the Atlantic Ocean in the Cenomanian reinforces the idea that South American and African populations would have maintained interchanges until the end of the Early Cretaceous or even until the Cenomanian (Medeiros and Schultz 2002, see Sereno et al 2004). However, the fossil record from the Laje do Coringa bone-bed in Brazil also includes apparently endemic taxa like the new dipnoiformes described here, namely Equinoxiodus alcantarensis gen. et sp.…”

“…In any case, this new record provides evidence that an effective isolation factor affecting at least some species was present by the early Cenomanian. Even in the event of a purported persistent transoceanic connection between South America and Africa through a narrow and shallow ocean (Cox 1980, Rage 1988, Buffetaut and Rage 1993, Sereno et al 2004, this would still probably represent a selective barrier for certain species.…”