Fossil taxa described in 1891

Torosaurus (meaning "perforated lizard", in reference to the large openings in its frill) is a genus of herbivorous chasmosaurine ceratopsian dinosaur that lived during the late Maastrichtian age of the Late Cretaceous period, between 68 and 66 million years ago, though it is possible that the species range might extend to as far back as 69 million years ago. Fossils have been discovered across the Western Interior of North America, from as far north as Saskatchewan to as far south as Texas.

Brontornis is an extinct genus of giant bird that inhabited Argentina during the Early to Middle Miocene. Its taxonomic position is highly controversial, with authors alternatively considering it to be a cariamiform, typically a phorusrhacid (terror bird) or an anserimorph.

Agrosaurus (; perhaps from Greek agros meaning 'field' and sauros meaning 'lizard', "field lizard") is a potentially dubious genus of thecodontosaurid sauropodomorph probably originating from the Magnesian Conglomerate of England that was originally believed to be a Triassic prosauropod from Australia. Agrosaurus would thus be the oldest dinosaur from that country. However, this appears to have been an error, and the material actually appears to come from Thecodontosaurus or a Thecodontosaurus-like animal from Bristol, England (Avon Fissure Fill). The type species is Agrosaurus macgillivrayi.

Calamosaurus (meaning "reed lizard") is a genus of small theropod dinosaur, from the Early Cretaceous of the Isle of Wight, England. It is based on two cervical vertebrae (NHMUK PV R 901), collected by Reverend William Fox. These fossils come from sedimentary rocks of the Wessex Formation and are Barremian in age. The type species of Calamosaurus, named Calamospondylus foxi by Richard Lydekker, was named in honour of Fox. Calamospondylus, however, was a preoccupied name, forcing Lydekker to change the genus name to Calamosaurus. This has subsequently led to immense confusion, with some authors

Necrolestes (from Ancient Greek νεκρός (necrós), meaning "dead", and λῃστής (lēistḗs), meaning "robber") is an extinct genus of mammals, which lived during the Early Miocene in what is now Argentine Patagonia. It is the most recent known genus of Meridiolestida, an extinct group of mammals more closely related to therians (marsupials and placentals) than to monotremes, which were the dominant mammals in South America during the Late Cretaceous. It contains two species, N. patagonensis and N. mirabilis; the type species N. patagonensis was named by Florentino Ameghino in 1891 based on remains f

Psilopterus (Greek for "bare wing") is an extinct genus of phorusrhacid ("terror bird") from the Middle Oligocene to possibly the Late Pleistocene of Argentina and Uruguay. Compared to other phorusrhacids, members of the genus are both relatively gracile and diminutive, and include the smallest known species of terror bird: with the head raised P. bachmanni was in height and weighed about , while the largest members of the genus were only about . The birds resemble the modern cariama (Cariama cristata), except with a heavier build and considerably smaller wings. Fossil finds in Uruguay indicat

Protoceras ('first horn') is an extinct genus of Artiodactyla, of the family Protoceratidae, endemic to North America. It lived from the Oligocene to the Early Miocene 33.3—16.0 Ma, existing for approximately .

species of insect (fossil)

Prothylacinus is an extinct genus of South American metatherian, that lived during the Early Miocene.

Patagornis is a genus of extinct flightless predatory birds of the family Phorusrhacidae. Known as "terror birds", these lived in what is now Argentina during the Early and Middle Miocene; the Santa Cruz Formation in Patagonia contains numerous specimens. Patagornis was an agile, medium sized Patagornithine and was likely a pursuit predator.

genus of mammals

Palaeospheniscus is an extinct genus of penguins belonging to the subfamily Palaeospheniscinae. These penguins are apparently not closely related to the modern genus Spheniscus.

species of insect (fossil)

Catonyx is an extinct genus of ground sloth of the family Scelidotheriidae, endemic to South America during the Pliocene and Pleistocene epochs. It lived from 2.5 Ma to about 10,000 years ago, existing for approximately . The most recent date obtained is about 9600 B.P.

Aegialornis is a genus of prehistoric apodiform birds. It formed a distinct family, the Aegialornithidae, and was in some ways intermediate between modern swifts and owlet-nightjars, lacking the more extreme adaptations to an aerial lifestyle that swifts show today, but already having sickle-shaped wings like them. They do not appear to be a direct ancestor of modern swifts, however, but rather a group that retained an overall basal morphology. Altogether, they were not too dissimilar from modern treeswifts.

Theriodictis is an extinct monotypic genus of cerdocyonine canid endemic to South America during the Middle Pleistocene.

Paraptenodytes is an extinct genus of penguins which contains two or three species sized between a Magellanic penguin and an emperor penguin (Aptenodytes forsteri). They are known from fossil bones ranging from a partial skeleton and some additional material in the case of P. antarcticus, the type specimen for the genus, and a single humerus in the case of P. brodkorbi. The latter species is therefore often considered invalid; a recent study considers it indeed valid, but distinct enough not to belong into Paraptenodytes. The fossils were found in the Santa Cruz and Chubut Provinces of Patagon

Prepotherium is an extinct genus of megatheriid ground sloths that lived during the Miocene period. Fossils of Prepotherium have been found in the Collón Curá and Santa Cruz Formations of Argentina.

species of bird (fossil)

Protoryx is an extinct genus of goat-antelope. A new species, P. tuvaensis, was described by E. L. Dmitrieva and N. V. Serdyuk in 2011, from Russia.

Opisthodactylus is an extinct genus of rheiform bird from the Early to Middle Miocene Santa Cruz and Chichinales Formations and the Late Miocene (Montehermosan) Andalhuala Formation of Argentina. Three species are described: the type species, O. patagonicus, O. kirchneri and O. horacioperezi. The species O. kirchneri was described in 2017 by Noriega et al. Fossils of O. horacioperezi were found together with fossils of Patagorhacos terrificus.

Ailuravus is a genus of prehistoric rodents in the family Ischyromyidae.

Pelecyodon is an extinct genus of ground sloths from the Early Miocene (Santacrucian) of South America.

Porolepis is an extinct genus of porolepiform sarcopterygian fish, from the Early Devonian Dniester Series of Ukraine, which is rich in Porolepis remains, and also the Nellen Koepfchen Beds of Germany. It lived alongside the dubious lophotrochozoan Macrodontophion. It was first described in 1858 but Porolepis was not named as a sufficient species until 1891.