Fossil taxa described in 1903

Brachiosaurus () is a genus of sauropod dinosaur that lived in North America during the Late Jurassic, about 155.6 to 145.5 million years ago. It was first described by American paleontologist Elmer S. Riggs in 1903 from fossils found in the Colorado River valley in western Colorado, United States. Riggs named the dinosaur Brachiosaurus altithorax; the generic name is Greek for "arm lizard", in reference to its proportionately long arms, and the specific name means "deep chest". Brachiosaurus is estimated to have been between long; body mass estimates of the subadult holotype specimen range fr

Ornitholestes (from Ancient Greek ὄρνις (órnis), meaning "bird", and λῃστής (lēistḗs), meaning "robber", and thus, "bird robber") is a small theropod dinosaur of the late Jurassic (Brushy Basin Member of the Morrison Formation, middle Kimmeridgian age, about 154 million years ago) of Western Laurasia (the area that was to become North America).

Haplocanthosaurus (meaning "simple spined lizard") is a genus of diplodocoid sauropod dinosaur. Two species, H. delfsi and H. priscus, are known from incomplete fossil skeletons. They lived during the Late Jurassic (Kimmeridgian stage), 155 to 152 million years ago in North America. The type species is H. priscus, named in 1903 John Bell Hatcher , and the referred species H. delfsi was discovered by a young college student named Edwin Delfs in Colorado, United States and described by Jack McIntosh and Michael Williams in 1988. Haplocanthosaurus specimens have been found in the lowermost layer

Telmatosaurus (meaning "marsh lizard") is a genus of basal hadrosauromorph dinosaur from the Late Cretaceous of Romania. It was relatively small for its group, measuring approximately in length and in body mass, which has been explained as an instance of insular dwarfism.

Therocephalia is an extinct group of therapsids (mammals and their close extinct relatives) from the Permian and Triassic periods. The therocephalians ("beast-heads") are named after their large skulls, which, along with the structure of their teeth, suggest that they were carnivores. Like other non-mammalian synapsids, therocephalians were once described as "mammal-like reptiles". Therocephalia is the group most closely related to the cynodonts, which gave rise to the mammals. Indeed, it had been proposed that therocephalians themselves may have given rise to the cynodonts, and therefore that

Brachauchenius (meaning 'short neck') is an extinct genus of pliosaurs that lived during the Late Cretaceous in what are now North America and North Africa. Only one species is known, B. lucasi, initially described by Samuel Wendell Williston in 1903 from a partial fossil skeleton discovered in a quarry in Kansas, United States. Many other fossil specimens attributed to the species were subsequently discovered, including an individual from Morocco whose presence was made official in 2016. Many contemporary pliosaur specimens were formerly attributed to Brachauchenius, but have since been reide

Proterosuchus is an extinct genus of archosauriform reptiles that lived during the Early Triassic. It contains three valid species: the type species P. fergusi and the referred species P. alexanderi and P. goweri. All three species lived in what is now South Africa. The genus was named in 1903 by the South African paleontologist Robert Broom. The genus Chasmatosaurus is a junior synonym of Proterosuchus.

Glyptotherium (from Ancient Greek for 'grooved or carved beast') is a genus of glyptodont (an extinct group of large, herbivorous armadillos) in the family Chlamyphoridae that lived from the Early Pliocene, about 3.9 million years ago, to the Late Pleistocene, around 15,000 years ago. It was widely distributed, living in the United States, Mexico, Guatemala, Costa Rica, Honduras, El Salvador, Panama, Venezuela, Colombia, and Brazil. Fossils that had been found in the Pliocene Blancan Beds in Llano Estacado, Texas were named Glyptotherium texanum by American paleontologist Henry Fairfield Osbor

Dyrosauridae is a family of extinct neosuchian crocodyliforms that lived from the Campanian to the Eocene. Dyrosaurid fossils are globally distributed, having been found in Africa, Asia, Europe, North America and South America. Over a dozen species are currently known, varying greatly in overall size and cranial shape. A majority were aquatic, some terrestrial and others fully marine (see locomotion below), with species inhabiting both freshwater and marine environments. Ocean-dwelling dyrosaurids were among the few marine reptiles to survive the Cretaceous–Paleogene extinction event.

Metacheiromys ("next to Cheiromys") is an extinct genus of placental mammals from extinct paraphyletic subfamily Metacheiromyinae within extinct paraphyletic family Metacheiromyidae in extinct order Palaeanodonta, that lived in North America (what is now Wyoming) from the early to middle Eocene.

Paramylodon is an extinct genus of ground sloth of the family Mylodontidae endemic to North America during the Pliocene through Pleistocene epochs, living from around ~4.9 Mya–12,000 years ago.

Toretocnemus (meaning 'perforated tibia') is an extinct genus of ichthyosaurs that lived during the Carnian stage of the Upper Triassic in what is now North America. Two species are known, T. californicus and T. zitelli, first described in 1903 by John Campbell Merriam from fossils discovered in the Hosselkus Limestone, Shasta County. The second species was first seen by Merriam as belonging to a distinct genus, but in 1999 it was reclassified into the original taxon. Toretocnemus fossils are primarily known from California, although some specimens are also reported from Alaska and Mexico. Wit

Lycosuchus is a genus of early therocephalian (an extinct type of therapsid, the group that modern mammals belong to) that lived roughly 260–258 million years ago, straddling the boundary of the Middle and Late Permian period, from what is now the Karoo Basin of South Africa. The type and only species is L. vanderrieti, named by paleontologist Robert Broom in 1903. Lycosuchus is known from a handful of well-preserved specimens mostly preserving the skull and lower jaw; the holotype specimen itself being a nearly complete and undistorted occluded skull and jaws. Other specimens have revealed mo

Megalohyrax is an extinct hyrax-grouped genus of herbivorous mammal that lived during the Oligocene, about 33-30 million years ago. Its fossils have been found in Africa and in Asia Minor.

Gemuendina stuertzi (named for Gemünden from where it was discovered) is a placoderm of the order Rhenanida, of the seas of Early Devonian Germany. In life, Gemuendina resembled a scaly ray with an upturned head, or a large-finned stargazer. G. stuertzi is often invoked as an example of convergent evolution- with its flat body and huge, wing-like pectoral fins it has a strong, albeit superficial similarity to rays. Unlike rays, however, both Gemuendina`s eyes and nostrils were placed atop the head, facing upward. Furthermore, G. stuertzi's upturned mouth would have enabled it to suction prey t

thumb|left|Life restoration Scylacosaurus is an extinct genus of therocephalian therapsids that lived during the Permian period. It contains one species Scylacosaurus sclateri.

Batrachosuchus is a genus of temnospondyl that existed from the Early to Middle Triassic of southern Africa (Ntawere Formation of Zambia and Burgersdorp Formation of South Africa) and the Blina Shale of Australia. The holotype is a skull registered at the Natural History Museum UK (NHMUK PV R 3589).

species of mollusc

Mantelliceras is an extinct ammonoid cephalopod genus belonging to the family Acanthoceratidae and type for the subfamily Mantelliceratinae, that lived from the Late Albian to the late Cenomanian stage of the Late Cretaceous.

Apatomerus (meaning "deceptive femur"), is a genus of extinct reptile known from a single fossil (KUVP 1199) from the Albian-age (Lower Cretaceous) Kiowa Shale of Kansas, USA. This bone, collected in 1893, was first identified as the thighbone of a crocodilian, but was described in 1903 by Samuel Wendell Williston as belonging to a pterosaur. This identification held through the 1970s, but has been abandoned. Recent summaries of pterosaur genera, such as Wellnhofer, 1991 and Glut, 2004 did not include it, and Mike Everhart, an authority on the rocks of the Western Interior Seaway (including th

Smilodectes is a genus of adapiform primate that lived in North America during the middle Eocene. It possesses a post-orbital bar and grasping thumbs and toes. Smilodectes has a small cranium size and the foramen magnum was located at the back of the skull, on the occipital bone.

thumb|left|Restoration by Charles R. Knight upright|thumb|left|Mare and foal at Ashfall Fossil Beds Neohipparion (Greek: "new" (neos), "pony" (hipparion)) is an extinct genus of equid, from the Neogene (Miocene to Pliocene) of North America and Central America.

species of mammal

Scymnosaurus is a dubious genus of therocephalian therapsids from the Middle Permian of what is now South Africa based upon the fossils of large, but indeterminate, early therocephalians. The genus and its type species S. ferox was named by Robert Broom in 1903, followed by S. watsoni in 1915. A third species, S. major, was named by Lieuwe Dirk Boonstra in 1954, who also referred many more specimens to the genus as Scymnosaurus sp.

Diceratosaurus is an extinct genus of nectridean tetrapodomorphs within the family Diplocaulidae. Fossils of Diceratosaurus were first described by Edward Drinker Cope in 1874. The species D. brevirostris is well known from Jefferson County, Ohio, with approximately 50 specimens having been collected from the Ohio Diamond Coal Mine. The mine was situated in the village of Linton, which became obscure soon after operations were completed and the mine closed in 1921. Diceratosaurus brevirostris dates back to the Mascovian period, 370 years ago.

Hughmilleria is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of Hughmilleria have been discovered in deposits of the Silurian age in China and the United States. Classified as part of the basal family Hughmilleriidae, the genus contains three species, H. shawangunk from the eastern United States, H. socialis from Pittsford, New York, and H. saetiger from Pennsylvania.'''''' The genus is named in honor of the Scottish geologist Hugh Miller.

Proterix is an extinct genus of erinaceid mammal from the Late Oligocene to the Early Miocene of North America.

Trigenicus is an extinct genus of small artiodactyl in the family Protoceratidae, endemic to North America. It lived from the Late Eocene 37.2—33.9 Ma, existing for approximately . Trigenicus resembled deer, but were more closely related to camelids.

Ictidosaurus was a therapsid genus found in the Abrahamskraal Formation of South Africa, which lived during the middle Permian period. Fossils of the type species were found in the Tapinocephalus (Capitanian age, 265.8-260.4 Ma), and the base of the Eodicynodon (Wordian age, 268–265.8 Ma) assembly zones, of the Karoo Basin. Older classifications of the species, along with many other specimens found in the Iziko South African Museum archives, were originally classified within therocephalian family names, in this case the Ictidosauridae, which has been reclassified as belonging to the Scylacosau

thumb|left|Fauna and depositional environment of the coeval Hakel and [[Hjoula localities, including Libanopristis]] Libanopristis is an extinct genus of ganopristid sclerorhynchoid that lived in Lebanon during the Late Cretaceous. One female specimen with nine embryos preserved in situ represents one of the first fossil evidence of batoid ovoviviparity.