Hyopsodontidae | |
---|---|
Hyopsodus | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Clade: | Panperissodactyla |
Family: | † Hyopsodontidae Trouessart, 1889 |
Genera | |
See text |
Hyopsodontidae is an extinct family of primitive mammals, initially assigned to the order Condylarthra, living from the Paleocene to the Eocene in North America and Eurasia. Condylarthra is now thought to be a wastebasket taxon; hyopsodontids have occasionally been speculated to be related to Afrotheria, [1] but the most recent consensus is that they are related to Perissodactyla. Analysis of the inner ear shows shared characteristics with the Equoidea (horses and paleotheres); [2] they may be a basal ungulate group near to perissodactyls. [3]
They were generally small omnivores, like many early mammals. The most common genus is Hyopsodus .
Members of the family were small by modern standards, ranging in size from a small rat to a raccoon. The hyopsodontids had many primitive mammal characteristics, including five-toed feet with claws and a complete dentition: a full set of incisors, canines, premolars, and molars. During the Paleocene in Europe, they reached a high diversity level, starting with Louisina and Monshyus in Hainin, Belgium, and following in the Cernaysian beds with Tricuspiodon , Paratricuspiodon , and Paschatherium . [4] High levels of diversity are also seen in Western North America in the Eocene within the genus Hyopsodus , with up to 18 named species, some of which are specific to particular locations over short spans of geologic time. This pattern suggests that at least some hyosodontids became quite specialized for specific ways of life. The group was not especially long-lived, but highly successful for its time, with fossil material in some areas suggesting large numbers of individuals. [5]
Perissodactyla is an order of ungulates. The order includes about 17 living species divided into three families: Equidae, Rhinocerotidae (rhinoceroses), and Tapiridae (tapirs). They typically have reduced the weight-bearing toes to three or one of the five original toes, though tapirs retain four toes on their front feet. The nonweight-bearing toes are either present, absent, vestigial, or positioned posteriorly. By contrast, artiodactyls bear most of their weight equally on four or two of the five toes: their third and fourth toes. Another difference between the two is that perissodactyls digest plant cellulose in their intestines, rather than in one or more stomach chambers as artiodactyls, with the exception of Suina, do.
Condylarthra is an informal group – previously considered an order – of extinct placental mammals, known primarily from the Paleocene and Eocene epochs. They are considered early, primitive ungulates. It is now largely considered to be a wastebasket taxon, having served as a dumping ground for classifying ungulates which had not been clearly established as part of either Perissodactyla or Artiodactyla, being composed thus of several unrelated lineages.
Phenacodus is an extinct genus of mammals from the late Paleocene through middle Eocene, about 55 million years ago. It is one of the earliest and most primitive of the ungulates, typifying the family Phenacodontidae and the order Perissodactyla.
South American native ungulates, commonly abbreviated as SANUs, are extinct ungulate-like mammals that were indigenous to South America from the Paleocene until the end of the Late Pleistocene. They represented a dominant element of South America's Cenozoic terrestrial mammal fauna prior to the arrival of living unguate groups in South America during the Pliocene and Pleistocene as part of the Great American Interchange. They comprise five major groups conventionally ranked as orders—Astrapotheria, Litopterna, Notoungulata, Pyrotheria, and Xenungulata—as well as the primitive "condylarth" groups Didolodontidae and Kollpaniinae. It has been proposed that some or all of the members of this group form a clade, named Meridiungulata, though the relationships of South American ungulates remain largely unresolved. The two largest groups of South American ungulates, the notoungulates and the litopterns, were the only groups to persist beyond the mid Miocene. Only a few species of notoungulates and litopterns survived until the end-Pleistocene extinction event around 12,000 years ago where they became extinct with most other large mammals in the Americas, shortly after the first arrival of humans into the region.
Miacis is an extinct genus of placental mammals from clade Carnivoraformes, that lived in North America from the early to middle Eocene.
Arctocyonidae is as an extinct family of unspecialized, primitive mammals with more than 20 genera. Animals assigned to this family were most abundant during the Paleocene, but extant from the late Cretaceous to the early Eocene . Like most early mammals, their actual relationships are very difficult to resolve. No Paleocene fossil has been unambiguously assigned to any living order of placental mammals, and many genera resemble each other: generalized robust, not very agile animals with long tails and all-purpose chewing teeth, living in warm closed-canopy forests with many niches left vacant by the K-T extinction.
Hyopsodus is a genus of extinct early ungulate mammal of the family Hyopsodontidae, a group associated with or basal to the Perissodactyla. It was a small mammal with skull of about 6 cm in length. Fossils of this genus have been found in the Eocene of North America, especially the Bighorn Basin region of the United States. It has also been found in Eurasia.
Tillodontia is an extinct suborder of eutherian mammals known from the Early Paleocene to Late Eocene of China, the Late Paleocene to Middle Eocene of North America where they display their maximum species diversity, the Middle Eocene of Pakistan, and the Early Eocene of Europe. Leaving no descendants, they are most closely related to the pantodonts, another extinct group. The tillodonts were medium- to large-sized animals that probably fed on roots and tubers in temperate to subtropical habitats.
The Clarkforkian North American Stage, on the geologic timescale, is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 56,800,000 to 55,400,000 years BP lasting 1.4 million years.
The Tiffanian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 60,200,000 to 56,800,000 years BP lasting 3.4 million years.
Phenacodontidae is an extinct family of large herbivorous mammals traditionally placed in the “wastebasket taxon” Condylarthra, which may instead represent early-stage perissodactyls. They lived from the late early Paleocene to early middle Eocene and their fossil remains have been found in North America and Europe. The only unequivocal Asian phenacodontid is Lophocion asiaticus.
Chacomylus is an extinct genus of odd-toed ungulate condylarth which existed in the Nacimiento Formation, United States during the early Paleocene period. It was first named by Thomas E. Williamson and Anne Weil in 2011 and the type species is Chacomylus sladei.
Gracilocyon is an extinct paraphyletic genus of placental mammals from clade Carnivoraformes, that lived in North America and Europe from the late Paleocene to the early Eocene.
Pleuraspidotherium is an extinct genus of condylarth of the family Pleuraspidotheriidae, whose fossils have been found in the Late Paleocene Marnes de Montchenot of France and the Tremp Formation of modern Spain.
This paleomammalogy list records new fossil mammal taxa that were described during the year 2012, as well as notes other significant paleomammalogy discoveries and events which occurred during that year.
The Willwood Formation is a sedimentary sequence deposited during the late Paleocene to early Eocene, or Clarkforkian, Wasatchian and Bridgerian in the NALMA classification.
Ocepeia is an extinct genus of afrotherian mammal that lived in present-day Morocco during the middle Paleocene epoch, approximately 60 million years ago. First named and described in 2001, the type species is O. daouiensis from the Selandian stage of Morocco's Ouled Abdoun Basin. A second, larger species, O. grandis, is known from the Thanetian, a slightly younger stage in the same area. In life, the two species are estimated to have weighed about 3.5 kg (7.7 lb) and 10 kg (22 lb), respectively, and are believed to have been specialized leaf-eaters. The fossil skulls of Ocepeia are the oldest known afrotherian skulls, and the best-known of any Paleocene mammal in Africa.
The Lignites de Soissonais is a geologic formation in the Var, Marne departments of France. It preserves fossils dating back to the Ypresian stage of the Eocene period.
The Silveirinha Formation is an Early Eocene geologic formation of the Mondego Basin in the Região Centro of central-western Portugal. The sandstones, siltstones and conglomerates were deposited in an alluvial environment.
Asmithwoodwardia is an extinct genus of mammals, from the order Litopterna. It lived during the Late Paleocene and the Early Eocene, and its fossilized remains were found in South America.