Condylarthra is an informal group – previously considered an order – of extinct

placental mammal Placental mammals (infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupialia. Placentalia contains the vast majority of extant mammals, which are partly distinguishe ...

s, known primarily from the

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...

and

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

epochs. They are considered early, primitive

ungulates Ungulates ( ) are members of the diverse clade Ungulata which primarily consists of large mammals with hooves. These include odd-toed ungulates such as horses, rhinoceroses, and tapirs; and even-toed ungulates such as cattle, pigs, giraffes, cam ...

. It is now largely considered to be a

wastebasket taxon Wastebasket taxon (also called a wastebin taxon, dustbin taxon or catch-all taxon) is a term used by some taxonomists to refer to a taxon that has the sole purpose of classifying organisms that do not fit anywhere else. They are typically defined ...

, having served as a dumping ground for classifying ungulates which had not been clearly established as part of either Perissodactyla or

Cetartiodactyla The even-toed ungulates (Artiodactyla , ) are ungulates—hoofed animals—which bear weight equally on two (an even number) of their five toes: the third and fourth. The other three toes are either present, absent, vestigial, or pointing poster ...

, being composed thus of several unrelated lineages.

Taxonomic history

Condylarthra always was a problematic group. When Condylarthra was first described by ,

Phenacodontidae Phenacodontidae is an extinct family (biology), family of large herbivorous mammals traditionally placed in the “wastebasket taxon” Condylarthra, which may instead represent early-stage Perissodactyla, perissodactyls. They lived in the Paleo ...

was the type and only family therein. , however, raised Condylarthra to an order and included a wide range of diverse placentals with generalized

dentition Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiolo ...

s and

postcranial skeleton Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated sk ...

s. More recent researchers (i.e. post-WW2) have been more restrictive; either including only a limited number of taxa, or proposing that the term should be abandoned altogether. Due to their primitive characteristics condylarths have been considered ancestral to several ungulate orders, including the living

Artiodactyla The even-toed ungulates (Artiodactyla , ) are ungulates—hoofed animals—which bear weight equally on two (an even number) of their five toes: the third and fourth. The other three toes are either present, absent, vestigial, or pointing poster ...

Cetacea Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...

, Perissodactyla,

Hyracoidea Hyraxes (), also called dassies, are small, thickset, herbivorous mammals in the order Hyracoidea. Hyraxes are well-furred, rotund animals with short tails. Typically, they measure between long and weigh between . They are superficially simil ...

Sirenia The Sirenia (), commonly referred to as sea-cows or sirenians, are an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. The Sirenia currently comprise two distinct f ...

, and

Proboscidea The Proboscidea (; , ) are a taxonomic order of afrotherian mammals containing one living family (Elephantidae) and several extinct families. First described by J. Illiger in 1811, it encompasses the elephants and their close relatives. From ...

, as well as the extinct

Desmostylia The Desmostylia (from Greek δεσμά ''desma'', "bundle", and στῦλος ''stylos'', "pillar") are an extinct order of aquatic mammals that existed from the early Oligocene (Rupelian) to the late Miocene ( Tortonian) (). Desmostylians are t ...

Embrithopoda Embrithopoda ("heavy-footed") is an order of extinct mammals known from Asia, Africa and Eastern Europe. Most of the embrithopod genera are known exclusively from jaws and teeth dated from the late Paleocene to the late Eocene; however, the orde ...

Litopterna Litopterna (from grc, λῑτή πτέρνα "smooth heel") is an extinct order of fossil hoofed mammals from the Cenozoic era. The order is one of the five great orders of South American ungulates that were endemic to the continent, until the G ...

Notoungulata Notoungulata is an extinct order of mammalian ungulates that inhabited South America from the early Paleocene to the Holocene, living from approximately 61 million to 11,000 years ago. Notoungulates were morphologically diverse, with forms resemb ...

, and

Astrapotheria Astrapotheria is an extinct order of South American and Antarctic hoofed mammals that existed from the late Paleocene to the Middle Miocene, ."The uruguaytheriine Astrapotheriidae from the rich middle Miocene Honda Group of the upper Magdalena R ...

. delimited condylarths as those having the following characters, but lacking the specializations present in more derived orders: * superior ramus of stapedial artery shifted to petrosal or lost *

mastoid foramen The mastoid foramen is a hole in the posterior border of the temporal bone. It transmits an emissary vein between the sigmoid sinus and the suboccipital venous plexus, and a small branch of the occipital artery, the posterior meningeal artery to t ...

lost *

bulla Bulla (Latin, 'bubble') may refer to: Science and medicine * Bulla (dermatology), a bulla * Bulla, a focal lung pneumatosis, an air pocket in the lung * Auditory bulla, a hollow bony structure on the skull enclosing the ear * Ethmoid bulla, pa ...

if present composed of

ectotympanic The ectotympanic, or tympanicum, is a bony structure found in all mammals, located on the tympanic part of the temporal bone, which holds the tympanic membrane (eardrum) in place. In catarrhine primates (including humans), it takes a tube-shape. ...

* relatively

bunodont The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...

teeth with low cusp relief *

trigonid The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone ...

s of lower molars shortened anteroposteriorly * large, posteriorly projecting hypoconulid on M₃ (lower third molar) * head of

astragalus ''Astragalus'' is a large genus of over 3,000 species of herbs and small shrubs, belonging to the legume family Fabaceae and the subfamily Faboideae. It is the largest genus of plants in terms of described species. The genus is native to tempe ...

is short and robust

Evolutionary history

The disappearance of the dinosaurs opened up an

ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of resources and competitors (for ...

for large mammalian

herbivore A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...

s. Some condylarths evolved to fill the niche, while others remained insectivorous. This may explain, in part, the tremendous

evolutionary radiation An evolutionary radiation is an increase in taxonomic diversity that is caused by elevated rates of speciation, that may or may not be associated with an increase in morphological disparity. Radiations may affect one clade or many, and be rapid ...

of the condylarths that we can observe throughout the Paleocene, resulting in the different groups of

ungulate Ungulates ( ) are members of the diverse clade Ungulata which primarily consists of large mammals with hooves. These include odd-toed ungulates such as horses, rhinoceroses, and tapirs; and even-toed ungulates such as cattle, pigs, giraffes, cam ...

s (or "

hoof The hoof (plural: hooves) is the tip of a toe of an ungulate mammal, which is covered and strengthened with a thick and horny keratin covering. Artiodactyls are even-toed ungulates, species whose feet have an even number of digits, yet the rumin ...

ed mammals") that form the dominant herbivores in most

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...

animal communities on land, except on the

island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island ...

continent of

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

. Among recent mammals,

Paenungulata Paenungulata (from Latin ''paene'' "almost" + ''ungulātus'' "having Hoof, hoofs") is a clade of "sub-Ungulate, ungulates", which groups three Extant taxon, extant mammal Order (biology), orders: Proboscidea (including elephants), Sirenia (sirenia ...

(

hyrax Hyraxes (), also called dassies, are small, thickset, herbivorous mammals in the order Hyracoidea. Hyraxes are well-furred, rotund animals with short tails. Typically, they measure between long and weigh between . They are superficially simil ...

es,

elephant Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantidae an ...

s, and

sea cow The Sirenia (), commonly referred to as sea-cows or sirenians, are an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. The Sirenia currently comprise two distinct f ...

s), Perissodactyla (

horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million y ...

rhinoceros A rhinoceros (; ; ), commonly abbreviated to rhino, is a member of any of the five extant species (or numerous extinct species) of odd-toed ungulates in the family Rhinocerotidae. (It can also refer to a member of any of the extinct species o ...

es, and

tapir Tapirs ( ) are large, herbivorous mammals belonging to the family Tapiridae. They are similar in shape to a pig, with a short, prehensile nose trunk. Tapirs inhabit jungle and forest regions of South and Central America, with one species inhabit ...

s),

(

pig The pig (''Sus domesticus''), often called swine, hog, or domestic pig when distinguishing from other members of the genus '' Sus'', is an omnivorous, domesticated, even-toed, hoofed mammal. It is variously considered a subspecies of ''Sus s ...

deer Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the reindeer ...

antelope The term antelope is used to refer to many species of even-toed ruminant that are indigenous to various regions in Africa and Eurasia. Antelope comprise a wastebasket taxon defined as any of numerous Old World grazing and browsing hoofed mammals ...

cow Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult ma ...

camel A camel (from: la, camelus and grc-gre, κάμηλος (''kamēlos'') from Hebrew or Phoenician: גָמָל ''gāmāl''.) is an even-toed ungulate in the genus ''Camelus'' that bears distinctive fatty deposits known as "humps" on its back. C ...

hippos A hippo or hippopotamus is either of two species of large African mammal which live mainly in and near water: * Hippopotamus * Pygmy hippopotamus Hippo or Hippos may also refer to: Toponymy * The ancient city of Hippo Regius (modern Annaba, Al ...

, and their relatives),

(

whale Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...

s), and

Tubulidentata Orycteropodidae is a family of afrotherian mammals. Although there are many fossil species, the only species surviving today is the aardvark, ''Orycteropus afer''. Orycteropodidae is recognized as the only family within the order Tubulidentata ...

(

aardvark The aardvark ( ; ''Orycteropus afer'') is a medium-sized, burrowing, nocturnal mammal native to Africa. It is the only living species of the order Tubulidentata, although other prehistoric species and genera of Tubulidentata are known. Unlike ...

s) are traditionally regarded as members of the Ungulata. Besides these, several extinct animals also belong to this group, especially the

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

n orders of ungulates, (

Meridiungulata South American native ungulates, commonly abbreviated as SANUs, are extinct ungulate-like mammals of controversial affinities that were indigenous to South America prior to the Great American Biotic Interchange. They comprise five major groups co ...

). Although many ungulates have hooves, this feature does not define the Ungulata. Indeed, some condylarths had small hooves on their feet, but the most primitive forms are

claw A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or tarsus ...

ed. Recent molecular and DNA research has reorganised the picture of mammalian evolution. Paenungulates and tubulidentates are seen as

afrotheria Afrotheria ( from Latin ''Afro-'' "of Africa" + ''theria'' "wild beast") is a clade of mammals, the living members of which belong to groups that are either currently living in Africa or of African origin: golden moles, elephant shrews (also know ...

ns, and no longer seen as closely related to the

laurasiatheria Laurasiatheria ("laurasian beasts") is a superorder of placental mammals that groups together true insectivores ( eulipotyphlans), bats ( chiropterans), carnivorans, pangolins ( pholidotes), even-toed ungulates (artiodactyls), odd-toed ungulates ...

n perissodactyls, artiodactyls, and cetaceans, implying that hooves were acquired independently (i.e. were

analogous Analogy (from Greek ''analogia'', "proportion", from ''ana-'' "upon, according to" lso "against", "anew"+ ''logos'' "ratio" lso "word, speech, reckoning" is a cognitive process of transferring information or meaning from a particular subject ( ...

) by at least two different mammalian lineages, once in the Afrotheria and once in the Laurasiatheria. Condylarthra itself, therefore, is

polyphyletic A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of converg ...

: the several condylarth groups are not closely related to each other at all. Indeed, Condylarthra is sometimes regarded as a 'wastebasket' taxon. True relationships remain in many cases unresolved. In addition to meridiungulates and living ungulates, a condylarthran ancestry has been proposed for several other extinct groups of mammals, including

Mesonychia Mesonychia ("middle claws") is an extinct taxon of small- to large-sized carnivorous ungulates related to artiodactyls. Mesonychids first appeared in the early Paleocene, went into a sharp decline at the end of the Eocene, and died out entirely ...

and

Dinocerata Dinocerata (from the Greek (), "terrible", and (), "horn") is an extinct order of plant-eating hoofed mammals with horns and protuberant canine teeth. Classification A 2015 phylogenetic study recovered Dinocerata as closely related to '' ...

Taxonomy

*Family

Arctocyonidae Arctocyonidae (from Greek '' arktos'' ''kyôn'', "bear/dog-like") has been defined 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 ex ...

(possibly

assemblage) **Genus ''

Arctocyon ''Arctocyon'' ('bear dog') is an extinct genus of ungulate mammals. ''Arctocyon'' was a "ground dwelling omnivore", that lived from 61.3-56.8 Ma. Synonyms of ''Arctocyon'' include ''Claenodon'', and ''Neoclaenodon''. ''Arctocyon'' was likely plant ...

'' **Genus ''

Chriacus ''Chriacus'' is an extinct genus of placental mammals that lived in what is now North America during the Paleocene epoch and died out after the early Eocene. In life, members of the genus would have looked something like a kinkajou or binturong, ...

'' *Family

Periptychidae Periptychidae is a family of Paleocene placental mammals, known definitively only from North America. The family is part of a radiation of early herbivorous and omnivorous mammals formerly classified in the extinct order " Condylarthra", which ...

**Genus ''

Ectoconus ''Ectoconus'' (Greek: "outside" (ektos), "cone" (konos)) is an extinct genus of terrestrial herbivorous mammal of the family Periptychidae, endemic to North America during the Early Paleocene subepochs (66—63.3 mya) existing for approximately ...

'' **Genus ''

Oxyacodon ''Oxyacodon'' is an extinct genus of condylarth of the family Periptychidae endemic to North America during the Early Paleocene living from 66 to 63.3 mya, existing for approximately . Taxonomy ''Oxyacodon'' was named by Osborn and Earle (18 ...

'' *Family

Hyopsodontidae Hyopsodontidae is an extinct family of primitive mammals from 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 be ...

(now established as within Perissodactyla) **Subfamily '' Tricuspiodontinae'' ***Genus '' Litomylus'' ***Genus '' Paratricuspiodon'' ***Genus '' Tricuspiodon'' **Genus ''

Aletodon ''Aletodon'' is a genus of ground dwelling insectivores, now extinct. The genus flourished from around 58.7 to 55.8 Ma. It was native to Colorado, Wyoming, and western North Dakota. Species There are currently 4 recognized species in this ge ...

'' **Genus '' Decoredon'' **Genus ''

Dipavali Diwali (), Dewali, Divali, or Deepavali ( IAST: ''dīpāvalī''), also known as the Festival of Lights, related to Jain Diwali, Bandi Chhor Divas, Tihar, Swanti, Sohrai, and Bandna, is a religious celebration in Indian religions. It is ...

'' **Genus '' Dorraletes'' **Genus '' Haplaletes'' **Genus '' Haplomylus'' **Genus ''

Hyopsodus ''Hyopsodus'' is a genus of extinct early ungulate mammal of the family Hyopsodontidae, a group associated with or basal to the Perissodactyla. Fossils of this genus have been found in the Eocene of North America, especially the Bighorn Ba ...

'' **Genus '' Louisina'' **Genus ''

Microhyus ''Microhyus'' is a genus of true weevils in the beetle family Curculionidae The Curculionidae are a family of weevils, commonly called snout beetles or true weevils. They are one of the largest animal families, with 6,800 genera and 83,000 spe ...

'' **Genus '' Midiagnus'' **Genus '' Oxyprimus'' **Genus '' Palasiodon'' **Genus ''

Paschatherium ''Paschatherium'' is a small extinct mammal of the Perissodactyla order, with an insectivore-like dentition. Its morphology indicates an arboreal form, adapted climbing and running on trees. ''Paschatherium'' must have been extremely numerous in ...

'' **Genus '' Utemylus'' **Genus '' Yuodon'' *Family Mioclaenidae *Family

(established as stem- Perissodactyla) **Subfamily Meniscotheriinae ***Genus ''

Ectocion ''Ectocion'' (sometimes ''Ectocyon'') is an extinct genus of placental mammals of the family Phenacodontidae. The genus was earlier classified as ''Gidleyina'' (Simpson 1935) and ''Prosthecion'' (Patterson and West 1973). Retrieved May 2013. Pa ...

'' ***Genus ''

Meniscotherium ''Meniscotherium'' is an extinct genus of dog-sized mammal which lived 54–38 million years ago. It was a herbivore and had hooves. Fossils have been found in Utah, New Mexico. and Colorado. Many individuals have been found together, indicating ...

'' **Genus ''

Almogaver ''Almogaver'' is an extinct possible odd-toed ungulate genus in the family Phenacodontidae. It was a ground-dwelling herbivore. It is known from the Tremp Basin in Spain , image_flag = Bandera de España.svg , image_coat ...

'' **Genus ''

Copecion ''Copecion'' was a genus of early herbivorous mammals that was part of the family Phenacodontidae Phenacodontidae is an extinct family of large herbivorous mammals traditionally placed in the “wastebasket taxon” Condylarthra, which may ins ...

'' **Genus '' Eodesmatodon'' **Genus ''

Phenacodus ''Phenacodus'' (Greek: "deception" (phenax), "tooth' (odus)) 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 fa ...

'' *Family Pleuraspidotheriidae **Genus ''

Hilalia ''Hilalia'' is an extinct genus of "condylarth" that lived during the Eocene. Fossils of ''Hilalia'' have been found at Uzunçarsidere Formation in Turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhur ...

'' **Genus ''

Orthaspidotherium ''Orthaspidotherium'' was a European Paleocene genus of early herbivorous mammals of the family Pleuraspidotheriidae. It was included in the family Meniscotheriidae by Teilhard de Chardin Pierre Teilhard de Chardin ( (); 1 May 1881 – 10 ...

'' **Genus '' Parabunodon'' **Genus ''

Pleuraspidotherium ''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 , image_flag ...

'' *Family Didolodontidae (stem-

) *Family Sparnotheriodontidae? (

) *Genus ''Tingamarra''? (non-descript therian mammal) *Genus ''Protungulatum'' (either non-placental eutherian or basal artiodactyl). *Genus ''Kharmerungulatum'' (a zhelestidJames David Archibald · Alexander Olegovich Averianov
Phylogenetic analysis, taxonomic revision, and dental ontogeny of the Cretaceous Zhelestidae (Mammalia: Eutheria)
Article · Feb 2012 · Zoological Journal of the Linnean Society)

Taxonomic history

Evolutionary history

Taxonomy

See also

Notes

References

External links