title: Neovenatorid theropods are apex predators in the Late Cretaceous of North America.
abstract: Allosauroid theropods were a diverse and widespread radiation of Jurassic-Cretaceous megapredators. Achieving some of the largest body sizes among theropod dinosaurs, these colossal hunters dominated terrestrial ecosystems until a faunal turnover redefined apex predator guild occupancy during the final 20 million years of the Cretaceous. Here we describe a giant new species of allosauroid--Siats meekerorum gen. et sp. nov.--providing the first evidence for the cosmopolitan clade Neovenatoridae in North America. Siats is the youngest allosauroid yet discovered from the continent and demonstrates that the clade endured there into the Late Cretaceous. The discovery provides new evidence for ecologic sympatry of large allosauroids and small-bodied tyrannosauroids. These data support the hypothesis that extinction of Allosauroidea in terrestrial ecosystems of North America permitted ecological release of tyrannosauroids, which went on to dominate end-Cretaceous food webs.
authors.affiliation: 1] Paleontology and Geology Research Laboratory, North Carolina Museum of Natural Sciences, Raleigh, North Carolina 27601, USA [2] Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina 27607, USA [3] Department of Geology, Field Museum of Natural History, Chicago, Illinois 60640, USA.
authors.forename: Lindsay E
authors.initials: LE
authors.lastname: Zanno
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Makovicky
mesh_terms: D000818:Animals; D025061:Dinosaurs; D020387:Food Chain; D005580:Fossils; D009656:North America; D010163:Paleontology; D010802:Phylogeny; D011235:Predatory Behavior