Dinosauria

A cast of BYU 9025, the holotype fossil of the sauropod dinosaur Supersaurus, a giant scapulocoracoid measuring 2.4m long. • The source photo was taken at the Dinosaur Journey Musuem. • Notes regarding the file; This image was edited and extracted from the original seen here. [1] The Photoshop CC lens correction profile and a 'perspective warp' correction were applied.

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.

Saurexallopus, a four toed dinosaur or bird trace fossil (jr syn Exallopus

Fossil samples – e.g. ‘primitive’ bony fish (1, 2), a skull of a temnospondyl ‘amphibian’ (probably a metoposauroid) in dorsal view (3), a skull of an archosaur of the crocodile lineage (probably a phytosaur) in palatal view (4), holotype of the “gliding reptile” Icarosaurus siefkeri [1] (5) and Atreipus-Grallator-type dinosaur tracks (bottom right) – from the Newark Supergroup, i.e. a series of mainly Late Triassic to Early Jurassic sedimentary rocks of eastern North America ↑ Edwin H. Colbert: A gliding reptile from the Triassic of New Jersey. American Museum Novitates, 2230. American Museum of Natural History, New York 1966, digitallibrary.amnh.org, cf. fig. 3 therein.

An Ankylosaurus head (cast of specimen AMNH 5214), on display at the Museum of the Rockies in Bozeman, Montana. This is from a specimen collected in Custer County, Montana. The Ankylosauria were armored dinosaurs that lived from 122 million years ago to 66 million years ago in western North America, Europe, and East Asia. There were two subgroups: The Nodosauridae and Ankylosauridae. The Ankylosauridae contained six species, and a single subfamily -- the Ankylosaurinae. There 18 genus within the subfamily, of which Ankylosaurus is the best known. Ankylosaurus as the last of these, and lived 65.5 to 66.5 million years ago. Ankylosaurus was about 20.5 feet long, 5 feet wide, and 5.5 feet tall at the hip. It walked on all fours, with the rear legs longer than the front ones. They ripped vegetation, and swallowed it whole. Their defining feature was their armor. They body was covered in thick, heavy bony plates, and most of the plates were fused together to make them even stronger. Embedded in the skin were more knobs of bone, and the outer skin above these knobs covered in keratin (the same stuff fingernails are made of). Ankylosaurus had a tail club, which consisted of several large osteoderms fused to the last few tail vertebrae. Ankylosaurus was discovered in 1908.

The "Dinosaurs in Their Time" exhibit at the Carnegie Museum of Natural History. Pictures from some of my free time during the Project Zero Perspectives conference (#PZPGH) in Pittsburg, Pennsylvania - May 2017.

Musango is a basal sauropodomorph dinosaur that lived during the Late Triassic period in what is now Zimbabwe. Typical of early sauropodomorphs, or "prosauropods," it was an obligate biped with a long neck, and a long tail for counterbalance. Musango grew to approximately 5 m in total body length.

Uragasaurus is a sauropod dinosaur, and the first mamenchisaurid known from Thailand. Mamenchisaurids exhibit the basic sauropod body plan, processing their herbivorous diet in their large gut. Uniquely, mamenchisaurid necks, like that of Uragasaurus, are proportionately long, even by sauropod standards.

Restored profile of the oviraptorid dinosaur Heyuannia yanshini by Matt Martyniuk.

Vitosaura is an abelisaurid theropod dinosaur that lived in what is now Argentina. It was a medium sized bipedal carnivore reaching around 6 m in total body length. Though only known from the pelvic girdle, Vitosaura likely had a blunt rugose snout, and extremely short arms, as these are typical traits of abelisaurs.

Isasicursor santacrucensis, an elasmarian ornithopod dinosaur.

Graph of relative Dinosaur fossil populations from each period of geologic time in the Mesozoic, ordered by major clade

Holotype skull of the centrosaurine ceratopsian dinosaur Diabloceratops eatoni from the Late Cretaceous (Campanian) of the Wahweap Formation, Grand Staircase-Escalante National Monument, Utah. Photograph by Nick Longrich, 2023.

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.

Figure 1. Evolution of macroecological traits in Dinosauria. Large scale event in dinosaur evolution (a); the origin of dinosaurs (star), hyperthermals (volcano), the earliest fossil Avialae (bird), the earliest fossil angiosperm (flower), the Cretaceous/Palaeogene mass extinction (asteroid). Phylogeny of dinosaurs (b) redrawn from Sereno and adapted to the current consensus and upon which an ancestral state reconstruction of temperature niche (mean annual temperature) after Chiarenza et al. is plotted; Mesozoic palaeogeographies (c) for Triassic (T), Jurassic (J) and Cretaceous (K). Silhouette colours symbolize body mass for each of the taxa represented; information on dietary habits are plotted after Barrett and Zanno & Makovicky; numbers represent clades discussed through this study: 1, Ornithischia; 2, Thyreophora; 3, Ornithopoda; 4, Hadrosauroidea; 5, Marginocephalia; 6, Ceratopsia; 7, Saurischia; 8, Sauropodomorpha; 9, Sauropoda; 10, Theropoda; 11, Ceratosauria; 12, Tetanurae; 13, Coelurosauria; 14, Maniraptoriformes; 15, Maniraptora; 16, Deinonychosauria; 17, Avialae; 18, Ornithothoraces. Palaeogeographies modified from original plots via R package ‘mapast’ using plate models by Scotese.

Diagram illustrating the "Temporal paradox" in paleontology. First given it's nickname by Alan Feduccia, the paradox is made up by the fact that almost all feathered dinosaurs are dated to have lived millions of years after Archaeopteryx, the oldest bird (late Jurassic, believed to have existed about 150 million years ago). Only a few of the feathered dinosaurs/birdlike dinosaurs are given an older date than Archaeopteryx.