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Temporal range: Early Eocene–Holocene
07. Camel Profile, near Silverton, NSW, 07.07.2007.jpg
A dromedary camel
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Suborder: Tylopoda
Illiger, 1811

and numerous prehistoric families (see text)


Tylopoda (meaning "calloused foot") [1] is a suborder of terrestrial herbivorous even-toed ungulates belonging to the order Artiodactyla. They are found in the wild in their native ranges of South America and Asia, while Australian feral camels are introduced. The group has a long fossil history in North America and Eurasia. Tylopoda appeared during the Eocene around 50 million years ago.

Tylopoda has only one extant family, Camelidae, which includes camels, llamas, guanacos, alpacas and vicuñas. This group was much more diverse in the past, containing a number of extinct families in addition to the ancestors of living camelids (see below).

Tylopods are not ruminants. [2]

Taxonomy and systematics

Tylopoda was named by Illiger (1811) and considered monophyletic by Matthew (1908). It was treated as an unranked clade by Matthew (1908) and as a suborder by Carroll (1988), Ursing et al. (2000) and Whistler and Webb (2005). It was assigned to Ruminantia by Matthew (1908); to Artiodactyla by Flower (1883) and Carroll (1988); to Neoselenodontia by Whistler and Webb (2005); and to Cetartiodactyla by Ursing et al. (2000) and by Agnarsson and May-Collado (2008). [3] [4] [5]

The main problem with circumscription of Tylopoda is that the extensive fossil record of camel-like mammals has not yet been thoroughly examined from a cladistic standpoint. Tylopoda is a highly distinctive lineage among the artiodactyls, but its exact relationships are somewhat elusive because the six living species are all closely related and can be considered "living fossils", the sole surviving lineage of a prehistorically wildly successful radiation. More recent studies suggest that tylopods are not as closely related to ruminants as traditionally believed, expressed in cladogram form as: [6] [7] [8] [9] [10] [11]


Tylopoda (camels) Cladogram of Cetacea within Artiodactyla (Camelus bactrianus).png


  Suina (pigs) Recherches pour servir a l'histoire naturelle des mammiferes (Pl. 80) (white background).jpg


  Ruminantia (ruminants) Walia ibex illustration white background.png  


  Hippopotamidae (hippopotamuses) Voyage en Abyssinie Plate 2 (white background).jpg

  Cetacea (whales) Bowhead-Whale1 (16273933365).jpg

Tylopoda are extremely conservative in their lifestyle and (like ruminants) seem to have occupied the same ecological niche since their origin over 40 million years ago. Thus, it seems that the previous assumption of a close relationship between Tylopoda and ruminants is simply because all other close relatives (whales, pigs etc.) are so divergent in their adaptations as to have obscured most indications of relationship, or at least those visible to phenetic analyses. However, the rather basal position that Tylopoda appears to have among the even-toed ungulates and relatives means that the oldest members of this lineage are still morphologically very primitive and hard to distinguish from the ancestors of related lineages. The first major modern and comprehensive analysis of the problem (in 2009) supported this; while some taxa traditionally considered Tylopoda could be confirmed to belong to this suborder (and a few refuted), the delimitation of this group is still very much disputed despite (or because of) an extensive fossil record. [6]

Life restoration of Agriochoerus antiquus Agriochoerus.jpg
Life restoration of Agriochoerus antiquus

The taxa currently assigned (with some reliability) to Tylopoda are: [6]

Basal and incertae sedis

Superfamily †Anoplotherioidea

Superfamily Cameloidea

Superfamily †Merycoidodontoidea (=Oreodontoidea)

Superfamily †Xiphodontoidea

Life restoration of the primitive artiodactyl Diacodexis pakistanensis (foreground) being stalked by Pakicetus Diacodexis pakistanensis e.jpg
Life restoration of the primitive artiodactyl Diacodexis pakistanensis (foreground) being stalked by Pakicetus

Disputed Tylopoda

Several additional prehistoric (cet)artiodactyl taxa are sometimes assigned to the Tylopoda, but other authors consider them incertae sedis or basal lineages among the (Cet)artiodactyla:

Some studies have considered Protoceratidae closely related to Tylopoda, but others have considered them more closely related to the ruminants. [12]

Related Research Articles

<span class="mw-page-title-main">Ungulate</span> Group of animals that walk on the tips of their toes or hooves

Ungulates are members of the diverse clade Euungulata which primarily consists of large mammals with hooves. Once part of the clade "Ungulata" along with the clade Paenungulata, "Ungulata" has since been determined to be a polyphyletic and thereby invalid clade based on molecular data. As a result, true ungulates had since been reclassified to the newer clade Euungulata in 2001 within the clade Laurasiatheria while Paenungulata has been reclassified to a distant clade Afrotheria. Living ungulates are divided into two orders: Perissodactyla including equines, rhinoceroses, and tapirs; and Artiodactyla including cattle, antelope, pigs, giraffes, camels, sheep, deer, and hippopotamuses, among others. Cetaceans such as whales, dolphins, and porpoises are also classified as artiodactyls, although they do not have hooves. Most terrestrial ungulates use the hoofed tips of their toes to support their body weight while standing or moving. Two other orders of ungulates, Notoungulata and Litopterna, both native to South America, became extinct at the end of the Pleistocene, around 12,000 years ago.

<span class="mw-page-title-main">Artiodactyl</span> Order of mammals

Artiodactyls are placental mammals belonging to the order Artiodactyla. Typically, they are ungulates which bear weight equally on two of their five toes: the third and fourth, often in the form of a hoof. The other three toes are either present, absent, vestigial, or pointing posteriorly. By contrast, most perissodactyls bear weight on an odd number of the five toes. Another difference between the two is that many artiodactyls digest plant cellulose in one or more stomach chambers rather than in their intestine as perissodactyls do. The advent of molecular biology, along with new fossil discoveries, found that cetaceans fall within this taxonomic branch, being most closely related to hippopotamuses. Some modern taxonomists thus apply the name Cetartiodactyla to this group, while others opt to include cetaceans within the existing name of Artiodactyla. Some researchers use "even-toed ungulates" to exclude cetaceans and only include terrestrial artiodactyls, making the term paraphyletic in nature.

<span class="mw-page-title-main">Hippopotamidae</span> Family of mammals

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 the cetaceans. They are sometimes referred to as hippopotamids.

<span class="mw-page-title-main">Ruminant</span> Hoofed herbivorous grazing or browsing mammals

Ruminants are herbivorous grazing or browsing artiodactyls belonging to the suborder Ruminantia that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions. The process, which takes place in the front part of the digestive system and therefore is called foregut fermentation, typically requires the fermented ingesta to be regurgitated and chewed again. The process of rechewing the cud to further break down plant matter and stimulate digestion is called rumination. The word "ruminant" comes from the Latin ruminare, which means "to chew over again".

<span class="mw-page-title-main">Camelidae</span> Family of mammals belonging to even-toed ungulates

Camelids are members of the biological family Camelidae, the only currently living family in the suborder Tylopoda. The seven extant members of this group are: dromedary camels, Bactrian camels, wild Bactrian camels, llamas, alpacas, vicuñas, and guanacos. Camelids are even-toed ungulates classified in the order Artiodactyla, along with species including whales, pigs, deer, cattle, and antelopes.

<span class="mw-page-title-main">Suina</span> Lineage of omnivorous, non-ruminant artiodactyl mammals that includes the pigs and peccaries

Suina is a suborder of omnivorous, non-ruminant artiodactyl mammals that includes the domestic pig and peccaries. A member of this clade is known as a suine. Suina includes the family Suidae, termed suids, known in English as pigs or swine, as well as the family Tayassuidae, termed tayassuids or peccaries. Suines are largely native to Africa, South America, and Southeast Asia, with the exception of the wild boar, which is additionally native to Europe and Asia and introduced to North America and Australasia, including widespread use in farming of the domestic pig subspecies. Suines range in size from the 55 cm (22 in) long pygmy hog to the 210 cm (83 in) long giant forest hog, and are primarily found in forest, shrubland, and grassland biomes, though some can be found in deserts, wetlands, or coastal regions. Most species do not have population estimates, though approximately two billion domestic pigs are used in farming, while several species are considered endangered or critically endangered with populations as low as 100. One species, Heude's pig, is considered by the International Union for Conservation of Nature to have gone extinct in the 20th century.

<span class="mw-page-title-main">Condylarthra</span> Grouping of extinct mammals

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.

<span class="mw-page-title-main">Laurasiatheria</span> Clade of mammals

Laurasiatheria is a superorder of placental mammals that groups together true insectivores (eulipotyphlans), bats (chiropterans), carnivorans, pangolins (pholidotes), even-toed ungulates (artiodactyls), odd-toed ungulates (perissodactyls), and all their extinct relatives. From systematics and phylogenetic perspectives, it is subdivided into order Eulipotyphla and clade Scrotifera. It is a sister group to Euarchontoglires with which it forms the magnorder Boreoeutheria. Laurasiatheria was discovered on the basis of the similar gene sequences shared by the mammals belonging to it; no anatomical features have yet been found that unite the group, although a few have been suggested such as a small coracoid process, a simplified hindgut and allantoic vessels that are large to moderate in size. The Laurasiatheria clade is based on DNA sequence analyses and retrotransposon presence/absence data. The superorder originated on the northern supercontinent of Laurasia, after it split from Gondwana when Pangaea broke up. Its last common ancestor is supposed to have lived between ca. 76 to 90 million years ago.

<span class="mw-page-title-main">Pecora</span> Infraorder of mammals

Pecora 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 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.

<span class="mw-page-title-main">Merycoidodontoidea</span> Extinct superfamily of mammals

Merycoidodontoidea, previously known as "oreodonts" or "ruminating hogs," are an extinct superfamily of prehistoric cud-chewing artiodactyls with short faces and fang-like canine teeth. As their name implies, some of the better known forms were generally hog-like, and the group has traditionally been placed within the Suina, though some recent work suggests they may have been more closely related to camels. "Oreodont" means "mountain teeth," referring to the appearance of the molars. Most oreodonts were sheep-sized, though some genera grew to the size of cattle. They were heavy-bodied, with short four-toed hooves and comparatively long tails.

<span class="mw-page-title-main">Carnivoramorpha</span> Clade of carnivores

Carnivoramorpha is a clade of placental mammals of clade Pan-Carnivora from mirorder Ferae, that includes the modern order Carnivora and its extinct stem-relatives.

<span class="mw-page-title-main">Cetruminantia</span> Taxonomic clade

The Cetruminantia are a clade made up of the Cetancodontamorpha and their closest living relatives, the Ruminantia.

<span class="mw-page-title-main">Oromerycidae</span> Extinct family of mammals

Oromerycidae is a small, extinct family of artiodactyls closely related to living camels, known from the early to late Eocene of western North America.

Paracamelus is an extinct genus of camel in the family Camelidae. It originated in North America and crossed the Beringian land bridge into Eurasia during the Late Miocene, approximately 7.5–6.5 million years ago (Ma). It is the presumed ancestor to living camels of the genus Camelus.

<span class="mw-page-title-main">Artiofabula</span> Clade of mammals comprising pigs, cows, hippos, and whales, among others

Artiofabula is a clade made up of the Suina and the Cetruminantia. The clade was found in molecular phylogenetic analyses and contradicted traditional relationships based on morphological analyses.

<span class="mw-page-title-main">Cetancodontamorpha</span> Clade of tetrapods

Cetancodontamorpha is a total clade of artiodactyls defined, according to Spaulding et al., as Whippomorpha "plus all extinct taxa more closely related to extant members of Whippomorpha than to any other living species". Attempts have been made to rename the clade Whippomorpha to Cetancodonta, but the former maintains precedent.

Duerotherium is an extinct genus of Paleogene artiodactyls known only from the Iberian Peninsula during the Middle Eocene, which contains one species D. sudrei. It, like other members of the Anoplotheriidae, was endemic to western Europe. The anoplotheriine was described from a left fragment of a maxilla from the Mazaterón Formation of the Duero Basin in 2009. Its dentition is mostly typical of the Anoplotheriinae but differs by an elongated plus triangular 3rd upper premolar and very specific traits of the molars. It is thought to have been part of an endemic faunal assemblage that evolved within the Iberian Peninsula by the Middle Eocene, where climates were subtropical.

<i>Xiphodon</i> Extinct genus of endemic Palaeogene European artiodactyls

Xiphodon is the type genus of the extinct Palaeogene artiodactyl family Xiphodontidae. It, like other xiphodonts, was endemic to western Europe and lived from the middle Eocene up to the earliest Oligocene. Fossils from Montmartre in Paris, France that belonged to X. gracilis were first described by the French naturalist Georges Cuvier in 1804. Although he designated the species to Anoplotherium, he recognized that it differed from A. commune by its dentition and limb bones, later designating it to its own subgenus in 1822. Xiphodon was promoted to genus rank by other naturalists in later decades. It is today defined by the type species X. gracilis and two other species X. castrensis and X. intermedium.

Ephelcomenus is an extinct genus of Paleogene artiodactyls endemic to western Europe. It contains one species E. filholi, which was first described by Richard Lydekker in 1889 but eventually classified to its own genus by the Swiss palaeontologist Johannes Hürzeler in 1938. It has an uncertain stratigraphic range, but some sources suggest that it was present in the Oligocene after the Grande Coupure turnover event of western Europe.

Robiatherium is an extinct genus of Paleogene artiodactyls containing one species R. cournovense. The genus name derives from the locality of Robiac in France where some of its fossil were described plus the Greek θήρ/therium meaning "beast" or "wild animal." It was known only from the middle Eocene and, like other anoplotheriids, was endemic to western Europe. The genus was erected by Jean Sudre in 1988 for a species originally attributed to the xiphodont genus Paraxiphodon in 1978. Robiatherium had dentitions typical of the subfamily Anoplotheriinae, differing from other genera by specific differences in the molars. It is one of the earliest-appearing anoplotheriine species in the fossil record as well as the earliest to have appeared in central Europe.


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