Cretaceous

A broken concretion with fossils inside; Late Cretaceous Pierre shale, near Ekalaka, Montana.

Anacleto and Allen fms. (Upper Cretaceous) in Auca Mahuida, Neuquen, Argentina.

Map of Cretaceous-aged dinosaur fossil localities of Mongolia. Gobihadros mongoliensis was collected from Bayshin Tsav in Area C. Open squares indicate Late Cretaceous sites, solid squares represent Early Cretaceous localities. Abbreviations: A, Localities of Western Gobi Desert in Mongolia, mainly group of localities of Nemegtian age (early Maastrichtian), Late Cretaceous; B, Localities of Central Gobi Desert in Mongolia, mainly Djadokhtian age (Campanian), Late Cretaceous; C & D- Localities of Eastern Gobi Desert in Mongolia, mainly Baynshirenian age (Cenomanian-Santonian), Late Cretaceous. Figure has been modified from Tsogtbaatar et al. 2014, Figure 1 [24].

Anacleto fm. (Upper Cretaceous) in Auca Mahuida, Neuquen, Argentina.

Candeleros fm. (Upper Cretaceous) near Cerro El Vagon, Neuquen, Argentina.

Plotosaurus bennisoni is a mosasaur from the Upper Cretaceous (Maastrichtian) North America.

A 1.7cm tall tooth from Liodon anceps. Cretaceous, Phosphate beds, Kouribga, Morocco.

Main evolutionary steps proposed for the morphofunctional and postural changes of the sauropod pedes. (A) Sauropod body mass through time (in metric tons) based on the sauropod body mass estimations of (41) (NB: data lacking for the second half of the Upper Cretaceous so illustrated here faded, in continuity with the data recorded in the Cretaceous). Schematic outlines of selected large specimens illustrated in the curve, including (from left to right) P. engelhardti, Vulcanodon karibaensis, R. brownei, G. brancai, Cedarosaurus weiskopfae, and Notocolossus gonzalezparejasi. (B) Projected evolutionary changes occurring in the sauropod pes associated with trend in body mass, including 1, skeletal and functional digitigrade pedal posture among basal non-sauropod sauropodomorphs with an incipient soft tissue pad (ISP) (see figs. S34 and S35); 2 and 3, expansion of a well-developed soft tissue pad beneath the elevated pedal bones (SP), resulting in a functionally plantigrade pes + retention of skeletal posture within a range of digitigrady; 4, retention of a soft tissue pad and yet undetermined trend toward more elevated bones; 5, conservation of the neomorphic soft tissue pad within all lineages. Selected examples of well-preserved non-sauropod sauropodomorph and sauropod pedal tracks illustrated above the trends, including (from left to right) Evazoum siriguii; Pseudotetrasauropus bipedoida, Eosauropus isp., Lavinipes cheminii; Kalosauropus pollex, Liujianpus shunan, Polyonyx gomesi; Parabrontopodus mcintoshi; Brontopodus birdi; Titanopodus mendozensis; and unnamed Asian sauropod track. Source of adapted drawing and notes are listed in table S9 and data S2.

Main evolutionary steps proposed for the morphofunctional and postural changes of the sauropod pedes. (A) Sauropod body mass through time (in metric tons) based on the sauropod body mass estimations of (41) (NB: data lacking for the second half of the Upper Cretaceous so illustrated here faded, in continuity with the data recorded in the Cretaceous). Schematic outlines of selected large specimens illustrated in the curve, including (from left to right) P. engelhardti, Vulcanodon karibaensis, R. brownei, G. brancai, Cedarosaurus weiskopfae, and Notocolossus gonzalezparejasi. (B) Projected evolutionary changes occurring in the sauropod pes associated with trend in body mass, including 1, skeletal and functional digitigrade pedal posture among basal non-sauropod sauropodomorphs with an incipient soft tissue pad (ISP) (see figs. S34 and S35); 2 and 3, expansion of a well-developed soft tissue pad beneath the elevated pedal bones (SP), resulting in a functionally plantigrade pes + retention of skeletal posture within a range of digitigrady; 4, retention of a soft tissue pad and yet undetermined trend toward more elevated bones; 5, conservation of the neomorphic soft tissue pad within all lineages. Selected examples of well-preserved non-sauropod sauropodomorph and sauropod pedal tracks illustrated above the trends, including (from left to right) Evazoum siriguii; Pseudotetrasauropus bipedoida, Eosauropus isp., Lavinipes cheminii; Kalosauropus pollex, Liujianpus shunan, Polyonyx gomesi; Parabrontopodus mcintoshi; Brontopodus birdi; Titanopodus mendozensis; and unnamed Asian sauropod track. Source of adapted drawing and notes are listed in table S9 and data S2.

Thescelosaurus neglectus, a hypsilophodont from the Late cretaceous of North America

Paleoartistic depiction of a Cretaceous forest of what is today the Tanis site, in North Dakota, hours after the K-Pg impact. We observe a burnt carcass of a Thescelosaurus, a impaled nanhsiungchelyid turtle, a small multituberculate mammal and a small ornithuran avialan.

Dorsal vertebra of platecarpus, a cretaceous. Mosasaur from the Niobrara Chalk of Kansas etc. General Collections Keywords: prehistoric archaeology; Paleopathology; Moodie, Roy Lee

Crâne de mosasaure d'espèce Platecarpus tympaniticus (squamates, mosasaures). Provenance : Smoky Hill Chalk, Kansas (aux Etats-Unis). Date : Crétacé supérieur, période du Campanien, 88 millions d'années avant notre ère. Collections du Muséum national d'histoire naturelle de Paris (France). Exposé à l'occasion de l'exposition "Un T-Rex à Paris" au Muséum national d'histoire naturelle de Paris (France) du 6 juin au 2 septembre 2018. Légende du fossile dans cette exposition : "Les mosasaures ne sont pas des dinosaures mais des reptiles marins, très répandus à la fin du Crétacé. Certains genres comme Globidens et Halisaurus sont connus aussi bien aux Etats-Unis qu'au Maroc. Ces animaux étaient d'excellents nageurs, capables de traverser l'Atlantique."

Holotype specimen TMP 2000.29.01 of the ophthalmosaurian ichthyosaur Athabascasaurus bitumineus from the Lower Cretaceous Clearwater Formation of Alberta, in Royal Tyrrell Museum, Drumheller, Alberta, Canada.

Life restoration of the mosasaurine mosasaurid Eremiasaurus, with unknown portions and soft tissues based primarily on Prognathodon and supplemented with Mosasaurus where needed. References Leblanc, A.R.H.; Caldwell, M.W.; Bardet, N. (2012). "A new mosasaurine from the Maastrichtian (Upper Cretaceous) phosphates of Morocco and its implications for mosasaurine systematics". Journal of Vertebrate Paleontology 32 (1): 82–104. Lindgren, J.; Kaddumi, H.; Polcyn, M. (2013). "Soft tissue preservation in a fossil marine lizard with a bilobed tail fin". Nature Communications 4: 2423. DOI:10.1038/ncomms3423. Konishi, T.; Brinkman, D.; Massare, J.A.; Caldwell, M.W. (2011). "New exceptional specimens of Prognathodon overtoni (Squamata, Mosasauridae) from the upper Campanian of Alberta, Canada, and the systematics and ecology of the genus". Journal of Vertebrate Paleontology 31 (5): 1026–1046. Russell, D.A. (1967). "Systematics and morphology of American mosasaurs". Bulletin of the Peabody Museum of Natural History 23: 1–241.

Simple drawing of Ankylosaurus magniventris, a North American Cretaceous ankylosaurid. Based on skeletal reconstruction in Paul 2010.