Crétacé

Comparison of cranial features between closely related southern Laramidian taxa; (A), Akainacephalus johnsoni (UMNH VP 20202) from the Late Cretaceous Kaiparowits Formation of Utah; and (B), Nodocephalosaurus kirtlandensis (SMP VP-900) from the Late Cretaceous Kirtland Formation of New Mexico, in left lateral views. Various synapomorphies are shared with N. kirtlandensis (highlighted in black and white arrows) and includes “flaring nostrils”; enlarged, laterally projecting, loreal osteoderms that are situated directly dorsal to the external nares. Other synapomorphies include pyramid-shaped nasal and frontal osteoderms positioned on the dorsal regions of the skull. A number of significant differences have been observed between both specimens; in A. johnsoni, the anterior, and posterior supraorbital bosses form an enlarged element that is somewhat backswept, whereas in N. kirtlandensis, the posterior and anterior supraorbital bosses are clearly defined as individual osteoderms, and are much smaller in size. Additionally, the squamosal horn in Akainacephalus is very small but is prominent and tetrahedrally shaped in Nodocephalosaurus. The quadratojugal horn in Akainacephalus is massive, has a subtriangular morphology in lateral view and projects almost entirely ventral, whereas in Nodocephalosaurus, the quadratojugal horn is smaller and has a typical fin-shaped morphology. Study sites: asob, anterior supraorbital boss; ext naris, external naris; laca, lacrimal caputegulum; loca, loreal caputegulum; naca, nasal caputegulae; orb, orbit; psob, posterior supraorbital boss; qjh, quadratojugal horn; sqh, squamosal horn.

Digital illustration of the Sauropod Dinosaur Isisaurus colberti from the Late Cretaceous (Maastrichtian) of India (72.2-66 MYA). References include Jain & Bandyopadhyay (1997), several papers from Wilson et al. and skeletal reconstruction by Scott Hartman. Illustrated by Ansh Saxena. About Isisaurus– Isisaurus colberti (=Titanosaurus colberti) was a species of Titanosaurian Sauropod Dinosaur from the Late Cretaceous (Maastrichtian) age in the Indian Subcontinent. Isisaurus lived sympatrically with another Titanosaurian Sauropod Jainosaurus. It also lived alongside Theropods like Rajasaurus, Rahiolisaurus, Indosuchus etc. Remains of Isisaurus come from the Lameta formation of Central India.

Eonatator sternbergi, a mosasaur from the Late Cretaceous of Kansas. Digital.

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

A photograph of partial specimen American Museum of Natural History (AMNH) 22555, posterior dorsal vertebrae, and the sacrum and pelvis (both iliae, and right ischium and pubis) of Anhanguera sp. (formerly often assigned to Anhanguera santanae),[1] from the Early Cretaceous Romualdo Formation (former Romualdo Member of the Santana Formation) of NE Brazil in dorsal view.

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

Reconstruction of Agustinia ligabuei from the Early Cretaceous of Argentina as a rebbachisaurid following Bellardini et al. 2022

Agustinia ligabuei, a sauropod from the Early Cretaceous of Argentina. Digital.

Pliosaurus (Luskhan itilensis) lived on the territory of the Volga region in the Hauterivian age of the Early Cretaceous period. Discovered in 2002 by G.N. Uspensky on the banks of the Volga near the village of Slantsevy Rudnik. This is the most complete pliosaurus skeleton found in Russia. This pliosaurus was not a predator and preferred to feed on fish and cephalopods.

Reconstruction of brachauchenin pliosaurid Luskhan itilensis. Early Cretaceous of Ulyanovsk region. 2017.

Reconstruction of Bissektipelta archibaldi an ankylosaurid dinosaur from the Late Cretaceous of Uzbekistan

Calvarius is a genus of styracosternan ornithopod from the Late Cretaceous of Spain. The name alludes to its chronostratigraphic proximity to the extinction event that wiped out the non-avian dinosaurs at the end of the Cretaceous. The highly modified metatarsal that is known from shows an example of convergent evolution, as it is more similar to non-iguanodontian ornithopods than to other styracosternans. It is thought that this is due to fulfilling a niche in its island habitat, resulting in Calvarius becoming a small-bodied animal, capable of rapid locomotion.

Astigmasaura is a medium-sized rebbachisaurid sauropod dinosaur from the Late Cretaceous period of what is now Argentina. Rebbachisaurids had highly pneumatized bones that helped them to hold their weight on their four pillar-like legs, and extremely long tails. Astigmasaura was likely a ground-level browsing herbivore.

Rebbachisaurids are the latest known sauropod dinosaurs outside the titanosaur lineage. Cienciargentina is a rebbachisaurid from the Late Cretaceous, making it among the most recent. It had many hollow bones, and likely had batteries of teeth used for chewing, a rebbachisaurid feature unique among sauropods.

Campananeyen is a rebbachisaurid sauropod that lived approximately 100 million years ago in the Late Cretaceous of what is now Argentina. Rebbachisaurids are the main group of diplodocoidea to have lived past the Jurassic, and had a more horizontal posture than contemporary sauropods, mainly the titanosaurs. They are unique among sauropods for having batteries of teeth used for chewing, rather than the typical peglike teeth sauropods used to strip leaves off branches.

Samrukia nesovi was originally described as a giant bird, but is now considered a pterodactyloid pterosaur of uncertain placement and validity. References: Naish, D., Dyke, G., Cau, A., Escuillié, F., & Godefroit, P. (2011). A gigantic bird from the Upper Cretaceous of Central Asia. Biology Letters, 8(1), 97–100. doi:10.1098/rsbl.2011.0683 Buffetaut, E. (2011). Samrukia nessovi, from the Late Cretaceous of Kazakhstan: A large pterosaur, not a giant bird. Annales de Paléontologie, 97(3–4), 133–138. doi:10.1016/j.annpal.2011.10.001