Fossil taxa described in 1858

extinct species of canids (Canidae)

Hadrosaurus (; ) is a genus of hadrosaurid ornithopod dinosaurs that lived in North America during the Late Cretaceous Period in what is now the Woodbury Formation in New Jersey about 83.6 to 77.9 million years ago. The holotype specimen was found in fluvial marine sedimentation, meaning that the corpse of the animal was transported by a river and washed out to sea. Some fossils are found in the Tar Heel/Coachman Formation.

Parahippus ("near to horse"), is an extinct equid, a relative of modern horses, asses, and zebras. It lived from 24 to 17 million years ago, during the Miocene epoch. It was very similar to Miohippus, but slightly larger, at around tall, at the withers. Their fossils have been found in North America, primarily in the Great Plains region and Florida.

Epicyon ("more than a dog") is a large, extinct, canid genus of the subfamily Borophaginae ("bone-crushing dogs"), native to North America. Epicyon existed for about from the early Clarendonian age of the Late Miocene to the late Hemphillian age of the Early Pliocene.'' E. haydeni'' is the largest known canid of all time, with the type species reaching 2.4 m (7.9 ft) in length, 90 cm (35 in) in shoulder height and approximately 100–125 kg (220–276 lb) in body mass. The largest known humerus specimen belonged to an individual weighing up to .

Psephoderma (meaning "pebbly skin", from the Ancient Greek psepho (ψῆφος), "pebbly", and derma (δέρμα), "skin") is a genus of placodonts very similar to the related genera Placochelys and Cyamodus. Psephoderma had a flattened skull and a narrow, straight rostrum, much narrower than that of its relatives. Inside this skull, embedded in the jaws, were rounded teeth specialized for crushing the shellfish it ate. Unlike henodontid placodonts, Psephoderma's carapace was divided into two pieces, one on the shoulders and back, and another on the ventral end. Psephoderma grew to long, larger than many

Simocyon ("short-snouted dog") is a genus of extinct carnivoran mammal in the family Ailuridae. Simocyon, which was about the size of a mountain lion, lived in the late Miocene and early Pliocene epochs, and has been found in Europe, Asia, and rarely, North America and Africa.

Hypohippus (Greek: "under" (hypos), "horse" (hippos)) is an extinct genus of three-toed horse, which lived 17–11 million years ago. It was the largest anchitherine equid about the size of a modern domestic horse, at and long. It was a long-necked, high-shouldered browser with sub-hypsodont, lophodont (rhino-like) dentition, that fed on the tough vegetation of forest understory and shrubs. Its deep preorbital fossae and retraction of the nasal notch hint at the presence of a long, muscular and prehensile upper lip that would aid during selective browsing. Overall its ecology would have been mor

Aelurodon is an extinct canid genus of the subfamily Borophaginae which lived from the Barstovian land mammal age () of the middle Miocene to the late Miocene epoch (). Aelurodon existed for approximately .

Grallator () is an ichnogenus (form taxon based on footprints) which covers a common type of small, three-toed print made by a variety of bipedal theropod dinosaurs. Grallator-type footprints have been found in formations dating from the Early Triassic through to the early Cretaceous periods. They are found in the United States, Canada, Europe, India, Australia, Brazil (Sousa and Santa Maria Formations) and China, but are most abundant on the east coast of North America, especially the Triassic and Early Jurassic formations of the northern part of the Newark Supergroup. The name Grallator tran

left|thumb|188x188px|Mummified Procamelus head Procamelus is an extinct genus of camel endemic to North America. It lived from the Middle to Late Miocene 16.3—5.3 mya, existing for approximately . The name is derived from the Greek πρό, meaning "before" or denoting priority of order, and κάμελος ("camel"), thus meaning "fore-camel", "early camel" or "predecessor camel".

thumb|Life reconstruction of C. albersdoerferi Cricosaurus is an extinct genus of marine crocodyliforms of the Late Jurassic. belonging to the family Metriorhynchidae. The genus was established by Johann Andreas Wagner in 1858 for three skulls from the Tithonian (Late Jurassic) of Germany. The name Cricosaurus means "Ring lizard", and is derived from the Greek '- ("ring") and -' ("lizard"). It was a relatively small reptile, with C. suevicus and C. araucanensis measuring and in total body length, respectively.

Merycochoerus (Greek: "ruminant" (merux)-like "swine" (khoiros)) is an extinct genus of oreodont of the family Merycoidodontidae, endemic to North America. They lived during the Early Oligocene 33.9—30.8 mya, existing for approximately . Fossils are widespread through the western United States.

Protohippus is an extinct three-toed genus of horse. It was roughly the size of a modern donkey. Fossil evidence suggests that it lived during the Late Miocene (Clarendonian to Hemphillian), from about 13.6 Ma to 5.3 Ma.

Pleuropholis is an extinct genus of prehistoric ray-finned fish.

Merychyus is an extinct genus of oreodont of the family Merycoidodontidae, endemic to North America. It lived during the Miocene, 20.4—10.3 mya, existing for approximately . Fossils are widespread through the central and western United States.

Chondrosteus ("cartilage bone" in Greek) is a genus of extinct marine actinopterygian (ray-finned fish) belonging to the family Chondrosteidae. It lived during the Hettangian and Sinemurian (early Early Jurassic) in what is now England. Chondrosteus is related to sturgeons and paddlefishes as part of the clade Acipenseriformes, and is one of the earliest known definitive members of the group. Similar to sturgeons, the jaws of Chondrosteus were free from the rest of the skull (projectile jaw system). Its scale cover was reduced to the upper lobe of the caudal fin like in paddlefish. It is repre

Pliolophus is an extinct equid that lived in the Early Eocene of Britain.

Hyperailurictis is an extinct genus of felid from Miocene North America. The Hyperailurictis species are Pseudaelurus-grade felids and thought to be the first felids in the Americas. ==Taxonomy and evolution== ===Taxonomic history=== In 1858, the paleontologist Joseph Leidy described a new species of cat, Felis intrepidus, based on lower jaw fragments (a left ramus, described, and a right ramus, mentioned only and now lost) found somewhere in Nebraska near the Niobrara river. The fragments were later determined to have come from the lower Valentine Formation, making them late Barstovian in ag