Crétacé supérieur

Phylogenetic relationships, chronostratigraphic, and paleoecological implications of M. intrepidus. a Graphic illustrating temporal range of North American tyrannosauroids including species-level range prior to the discovery of M. intrepidus, extension of current range, and hypothesized range based on isolated teeth12. The current gap in the North American tyrannosauroid record spans from the Tithonian to the Aptian. Faunal composition of Late Cretaceous ecosystems was established between the Albian and Turonian, as recognized by the stratigraphic appearance of major clades (see refs. 7,12 and references therein). b generalized phylogenetic relationships of Tyrannosauroidea, showing the appearance of select traits related to cursoriality in tyrannosaurs that are newly optimized as a result of the discovery of M. intrepidus. Tree topology follows this study using the modified dataset of Carr and colleagues27. Coelurus and Tanycolagreus are grafted as basal tyrannosauroids following Brusatte and colleagues5. c Stratigraphic distribution of Allosauria in North America (incl. Megaraptora but see ref. 70 for alternative hypotheses regarding this clade) documents overlap with M. intrepidus in early Late Cretaceous ecosystems leading to (d) refined calibration on the origin of late diverging tyrannosauroids and clade-level faunal turnover within apex predator roles throughout the Late Jurassic–Late Cretaceous of North America. Colored polygons are stylized call-outs and are not intended to reflect two-dimensional data. Temporal data corresponding to this figure are available in Supplementary Table 5

Clidastes propython, a mosasaur from the Late Cretaceous of Kansas, digital.

A map showing the distribution of paraves in Late Cretaceous with the respective paleogeographic setting.

Diuqin is an unenlagiine dinosaur from the Late Cretaceous of what is now Argentina. Unenlagiines, known exclusively from South America, are usually classified as dromaeosaurs though this is sometimes debated. Like dromaeosaurs, they were covered in feathers, carnivorous, and had the large sickle-like claw on the inner toe of each foot. Unique to unenlagiines is their elongated snout, suggesting a piscivorous diet. Diuqin was a medium-sized unenlagiine, at about 4 m in length.

Elasmosaurus platyurus, plesiosaurian from Late Cretaceous (Campanian) of North America

Elasmosaurus platyurus, plesiosaurian from Late Cretaceous (Campanian) of North America

Majungasaurus crenatissimus, an abelisaur from the Late Cretaceous of Madagascar, pencil drawing

Chasmosaurus belli ROM 843, Royal Tyrrell Museum of Paleontology. Late Cretaceous 75-74.5 millions years ago. Found at Dinosaur Provincial Park, Alberta, and prepared at the Royal Tyrrell Museum of Paleontology, Drumheller, Alberta.

Chasmosaurus belli ROM 843, Royal Tyrrell Museum of Paleontology. Late Cretaceous 75-74.5 millions years ago. Found at Dinosaur Provincial Park, Alberta, and prepared at the Royal Tyrrell Museum of Paleontology, Drumheller, Alberta.

Hypothetical reconstruction of the Late Cretaceous abelisaurid Elemgasem nubilus.

Life reconstruction of the Late Cretaceous south american paravian, Overoraptor chimentoi

Forearm and hand of Machairasaurus leptorhynchos Longrich et al. 2010 (Dinosauria: Theropoda: Oviraptoridae: Ingeniinae) from the Late Cretaceous Djadokhta Formation beds of Bayan Mandahu, Inner Mongolia, China. Digital photography and editing by Nick Longrich

Ceratonykus oculatus, Late Cretaceous of Mongolia. Digital.

Speculative reconstruction of Aoniraptor'’ from the Late Cretaceous of Argentina, here restored as a megaraptoran as recovered by most studies

Skull diagram featuring the holotype skull (ROM 1790) of the ornithomimid Rativates evadens, from the Late Cretaceous period. Abbreviations: d, dentary; f, frontal; l, lacrimal; m, maxilla; n, nasal; pm, premaxila; ps, paraphenoid.

Holotype maxilla of the lambeosaurine hadrosaurid Ajnabia odysseus from the Late Cretaceous (late Maastrichtian) of Sidi Chennane, Morocco