18-572: Bovoidea is a superfamily of pecoran ruminants containing the Bovidae and Moschidae . The Bovoidea today is defined in part by very specific dental and anatomical traits, and genetic research indicates that the Moschidae is the sister taxon to the Bovidae. This prehistoric even-toed ungulate -related article is a stub . You can help Misplaced Pages by expanding it . Pecoran Pecora
36-581: A clade sister to Cervidae . According to the study, Cervidae diverged from the Bovidae-Moschidae clade 27 to 28 million years ago. The following cladogram is based on the 2003 study. Tragulidae [REDACTED] Antilocapridae [REDACTED] Giraffidae [REDACTED] Cervidae [REDACTED] Bovidae [REDACTED] Moschidae [REDACTED] Infraorder Pecora ("horned ruminants", "higher ruminants") Pecorans share characteristics with other artiodactyls, including
54-499: A common ancestor, but instead evolved independently on at least two occasions. Likewise, while Pecora as a group is supported by both molecular and morphological studies, morphological support for interrelationships between pecoran families is disputed. The first fossil ruminants appeared in the Early Eocene and were small, likely omnivorous , forest-dwellers. Molecular dating studies estimate that Ruminantia split into
72-428: A four-chambered stomach, and a paraxonic foot, meaning that it supports weight on the third and fourth digits. Several characteristics distinguish Pecora from its sister taxon, Tragulina : an astragalus with parallel sides, a loss of the trapezium , and differences in parts of the skull such as the petrosal bone . The distinguishing features of most pecoran families are cranial appendages. Most modern pecorans (with
90-521: Is an infraorder of even-toed hoofed mammals with ruminant digestion. Most members of Pecora have cranial appendages projecting from their frontal bones ; only two extant genera lack them, Hydropotes and Moschus . The name "Pecora" comes from the Latin word pecus , which means "cattle". Although most pecorans have cranial appendages, only some of these are properly called "horns", and many scientists agree that these appendages did not arise from
108-643: Is an infraorder within the larger suborder Ruminantia , and is the sister clade to the infraorder Tragulina (of which Tragulidae is the only surviving family ). Pecora's placement within Artiodactyla can be represented in the following cladogram : Tylopoda (camels) [REDACTED] Suina (pigs) [REDACTED] Tragulidae (mouse deer) [REDACTED] Pecora (horn bearers) [REDACTED] Hippopotamidae (hippopotamuses) [REDACTED] Cetacea (whales) [REDACTED] Current attempts to determine
126-560: Is given in the table below: The hippopotamids are descended from the anthracotheres , a family of semiaquatic and terrestrial artiodactyls that appeared in the late Eocene , and are thought to have resembled small- or narrow-headed hippos. The hippos split off from the anthracotheres some time during the Miocene . The oldest records of Hippopotamidae are from Afro-Arabia and date to the late Miocene, approximately 7.4 million years ago, expanding into Eurasia around 6 million years ago. After
144-411: Is relatively thin, so hippos dehydrate rapidly in dry environments. Both the incisors and canines are large and tusk-like, although the canine tusks are by far the larger. The tusks grow throughout life. The postcanine teeth are large and complex, suited for chewing the plant matter that comprises their diets. The number of incisors varies even within the same species, but the general dental formula
162-500: Is shown to be closely related to their environment and anatomy, where light Pecorian species use both flexed and extended suspensions in their fast gallops. The white-tail and mule-deer have been observed to primarily use the extended suspension, since in this phase of their gallop they leap over bushes and logs that are present in their brush environment. However, heavy Pecorian species do not use extended suspensions as most have backs that slope downward with shorter hind legs. Pecora
180-509: The Miocene suggests that its rapid diversification may correspond to the climate change events of that epoch, as this time period was marked by much of Earth's forest habitats being replaced by grasslands due to widespread cooling and drying. It is likely that the antelopes, giraffids, and pronghorns evolved in an open environment while the cervids, including the caribou, evolved in a woodland habitat. The type of gallop in Pecorian species
198-563: The cetaceans . They are sometimes referred to as hippopotamids . There are two living species of hippopotamid in two genera; the pygmy hippo, Choeropsis liberiensis of the forests of west Africa, and the common hippo, Hippopotamus amphibius . The term hippopotamus can also be applied to hippopotamids in general, although it is most frequently used for the common hippo and its respective genus . Hippopotamids are large mammals, with short, stumpy legs, and barrel-shaped bodies. They have large heads, with broad mouths, and nostrils placed at
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#1732775387807216-400: The appearance of the hippopotamids, the remaining anthracotheres went into a decline brought about by a combination of climatic change and competition with their descendants, until the last genus, Merycopotamus , died out in the early Pliocene of India. There were once many species of hippopotamid, but only two survive today: Hippopotamus amphibius , and Choeropsis liberiensis . They are
234-493: The exception of the Moschidae ) have one of four types of cranial appendages: horns, antlers, ossicones, or pronghorns. Hippopotamidae † Trilobophorus Geze, 1985 Hippopotamidae is a family of stout, naked-skinned , and semiaquatic artiodactyl mammals, possessing three-chambered stomachs and walking on four toes on each foot. While they resemble pigs physiologically, their closest living relatives are
252-629: The genus Hexaprotodon , which is now largely restricted to South Asia and Southeast Asia, formerly included many fossil hippopotamuses that are now thought to be unrelated. Hippopotamidae's placement within Artiodactyla can be represented in the following cladogram : Tylopoda (camels and kin) [REDACTED] Suina (pigs and kin) [REDACTED] Ruminantia (ruminants) [REDACTED] Hippopotamidae (hippopotamids) [REDACTED] Cetacea (whales) [REDACTED] The lower canine teeth of hippopotamids are similar in function and structure to
270-432: The last survivors of two major evolutionary lineages, the hippos proper and the pygmy hippos, respectively; these lineages could arguably be considered subfamilies , but their relationship to each other – apart from being fairly distant relatives – is not well resolved. The enigmatic Miocene Kenyapotamus is insufficiently known to be assigned a place in the hippo phylogeny with any degree of certainty. In addition,
288-645: The relationships among pecoran families (as well as all artiodactyls) rely on molecular studies, as little consensus exists in morphological studies. Different families within Pecora are recognized as valid by different groups of scientists. Until the beginning of the 21st century it was understood that the family Moschidae (musk deer) was sister to Cervidae . However, a 2003 phylogenetic study by Alexandre Hassanin (of National Museum of Natural History, France ) and colleagues, based on mitochondrial and nuclear analyses, revealed that Moschidae and Bovidae form
306-452: The top of their snouts. Like pigs, they have four toes, but unlike pigs, all of the toes are used in walking. Hippopotamids are unguligrade , although, unlike most other such animals, they have no hooves, instead using a pad of tough connective tissue on each foot. Their stomachs have three chambers, but they are not true ruminants . The living species are smooth-skinned and lack both sebaceous glands and sweat glands . The outer epidermis
324-516: The two sister clades Pecora and Tragulina around 45 million years ago, during the Eocene . However, it was not until 15 million years later, at around 30 million years ago during the Oligocene , that the evolutionary radiation of Pecora began and the five families appeared ( Bovidae , Cervidae , Moschidae , Giraffidae , and Antilocapridae ). The appearance of many Pecoran fossils during
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