Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Megaclassis: Osteichthyes
Cladus: Sarcopterygii
Cladus: Rhipidistia
Cladus: Tetrapodomorpha
Cladus: Eotetrapodiformes
Cladus: Elpistostegalia
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Cladus: Synapsida
Cladus: Eupelycosauria
Cladus: Sphenacodontia
Cladus: Sphenacodontoidea
Cladus: Therapsida
Cladus: Theriodontia
Cladus: Cynodontia
Cladus: Eucynodontia
Cladus: Probainognathia
Cladus: Prozostrodontia
Cladus: Mammaliaformes
Classis: Mammalia
Cladus: Theriimorpha
Cladus: Theriiformes
Cladus: Trechnotheria
Cladus: Zatheria
Subclassis: Theria
Cladus: Eutheria
Infraclassis: Placentalia
Magnordo: Boreoeutheria
Superordo: Laurasiatheria
Ordo: †Condylarthra
Familiae: †Arctocyonidae - †Hyopsodontidae
Vernacular names
español: Condilartros
日本語: 顆節目
русский: Кондиляртры
Condylarthra is an informal group – previously considered an order – of extinct placental mammals, known primarily from the Paleocene and Eocene epochs.[1] They are considered early, primitive ungulates and 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.[2][3][4]
Taxonomic history
Condylarthra always was a problematic group. When first described by Cope 1881, Phenacodontidae was the type and only family therein. Cope 1885, however, raised Condylarthra to an order and included a wide range of diverse placentals with generalized dentitions and postcranial skeletons. 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.[5] Due to their primitive characteristics condylarths have been considered ancestral to several ungulate orders, including the living Artiodactyla, Cetacea, Perissodactyla, Hyracoidea, Sirenia, and Proboscidea, as well as the extinct Desmostylia, Embrithopoda, Litopterna, Notoungulata, and Astrapotheria.[6]
Prothero, Manning & Fischer 1988 delimited condylarths as those having the following characters, but lacking the specializations present in more derived orders:[5]
superior ramus of stapedial artery shifted to petrosal or lost
mastoid foramen lost
bulla if present composed of ectotympanic
relatively bunodont teeth with low cusp relief
trigonids of lower molars shortened anteroposteriorly
large, posteriorly projecting hypoconulid on M3 (lower third molar)
head of astragalus is short and robust
Evolutionary history
Ectocion, a small plant-eating phenacodontid found in Wyoming
The disappearance of the non-avian dinosaurs opened up an ecological niche for large mammalian herbivores. Some condylarths evolved to fill the niche, while others remained insectivorous. This may explain, in part, the tremendous evolutionary radiation of the condylarths that we can observe throughout the Paleocene, resulting in the different groups of ungulates (or "hoofed mammals") that form the dominant herbivores in most Cenozoic animal communities on land, except on the island continent of Australia.
Among recent mammals, Paenungulata (hyraxes, elephants, and sea cows), Perissodactyla (horses, rhinoceroses, and tapirs), Artiodactyla (pigs, deer, antelope, cows, camels, hippos, and their relatives), Cetacea (whales), and Tubulidentata (aardvarks) are traditionally regarded as members of the Euungulata.[1][7] Besides these, several extinct animals also belong to this group, especially the endemic South American orders of ungulates, (Meridiungulata). Although many ungulates have hooves, this feature does not define the Euungulata. Indeed, some condylarths had small hooves on their feet, but the most primitive forms are clawed.
Recent molecular and DNA research has reorganised the picture of mammalian evolution. Paenungulates and tubulidentates are seen as afrotherians, and no longer seen as closely related to the laurasiatherian perissodactyls, artiodactyls, and cetaceans,[8][9] implying that hooves were acquired independently (i.e. were analogous) by at least two different mammalian lineages, once in the Afrotheria and once in the Laurasiatheria. Condylarthra itself, therefore, is polyphyletic: the several condylarth groups are not closely related to each other at all. Indeed, Condylarthra is sometimes regarded as a 'wastebasket' taxon.[4] 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[10] and Dinocerata.[11]
Taxonomy
Family Arctocyonidae (possibly polyphyletic assemblage)[12]
Genus Arctocyon
Genus Chriacus
Family Periptychidae
Genus Ectoconus
Genus Oxyacodon
Family Hyopsodontidae (now established as within Perissodactyla)[13]
Subfamily Tricuspiodontinae
Genus Litomylus
Genus Paratricuspiodon
Genus Tricuspiodon
Genus Aletodon
Genus Decoredon
Genus Dipavali
Genus Dorraletes
Genus Haplaletes
Genus Haplomylus
Genus Hyopsodus
Genus Louisina
Genus Microhyus
Genus Midiagnus
Genus Oxyprimus
Genus Palasiodon
Genus Paschatherium
Genus Utemylus
Genus Yuodon
Family Mioclaenidae
Family Phenacodontidae (established as stem-Perissodactyla)[14]
Subfamily Meniscotheriinae
Genus Ectocion
Genus Meniscotherium
Genus Almogaver
Genus Copecion
Genus Eodesmatodon
Genus Phenacodus
Family Pleuraspidotheriidae[15]
Genus Hilalia
Genus Orthaspidotherium
Genus Parabunodon
Genus Pleuraspidotherium
Family Didolodontidae (stem-Meridiungulata)
Family Sparnotheriodontidae? (Litopterna)
Genus Tingamarra? (non-descript therian mammal)
Genus Protungulatum (either non-placental eutherian or basal artiodactyl).[16]
Genus Kharmerungulatum (a zhelestid[17])
See also
Evolution of mammals
List of prehistoric mammals
Notes
McKenna & Bell 1997
Naish, Darren (8 August 2013). "Phenacodontidae, I feel like I know you". Tetrapod Zoology. Scientific American. Archived from the original on 10 March 2014.
Cooper, L. N.; Seiffert, E. R.; Clementz, M.; Madar, S. I.; Bajpai, S.; Hussain, S. T.; Thewissen, J. G. M. (2014-10-08). "Anthracobunids from the Middle Eocene of India and Pakistan Are Stem Perissodactyls". PLOS ONE. 9 (10): e109232. Bibcode:2014PLoSO...9j9232C. doi:10.1371/journal.pone.0109232. PMC 4189980. PMID 25295875.
Janis 1993
Thewissen 1990, p. 20
Rose, Kenneth D. (2006). "Archaic Ungulates". The beginning of the Age of Mammals. Baltimore: Johns Hopkins University Press. ISBN 9780801892219.
Novacek 1986
Madsen et al. 2001
Murphy et al. 2001
Van Valen 1966
Van Valen 1988
Smith, De Bast. "Reassessment of the Small ‘Arctocyonid’ Prolatidens waudruae from the Early Paleocene of Belgium, and Its Phylogenetic Relationships with Ungulate-Like Mammals". Journal of Vertebrate Paleontology. Retrieved August 2013
Ravel, Anthony; Orliac, Maeva (2014). "The inner ear morphology of the 'condylarthran' Hyopsodus lepidus". Historical Biology. 27 (8): 8. doi:10.1080/08912963.2014.915823. S2CID 84391276.
Cooper, L. N.; Seiffert, E. R.; Clementz, M.; Madar, S. I.; Bajpai, S.; Hussain, S. T.; Thewissen, J. G. M. (2014). "Anthracobunids from the Middle Eocene of India and Pakistan Are Stem Perissodactyls". PLOS ONE. 9 (10): e109232. Bibcode:2014PLoSO...9j9232C. doi:10.1371/journal.pone.0109232. PMC 4189980. PMID 25295875.
Halliday, T.J.D.; Upchurch, P.; Goswami, A. (2017). "Resolving the relationships of Paleocene placental mammals". Biological Reviews. 92 (1): 521–550. doi:10.1111/brv.12242. PMC 6849585. PMID 28075073.
Archibald, J. David; Zhang, Yue; Harper, Tony; Cifelli, Richard L. (May 6, 2011). "Protungulatum, confirmed Cretaceous occurrence of an otherwise Paleocene eutherian (placental?) mammal" (PDF). Journal of Mammalian Evolution. 18 (3): 153–161. doi:10.1007/s10914-011-9162-1. S2CID 16724836. Archived from the original (PDF) on March 3, 2016. Retrieved April 28, 2013.
James 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
References
Cope, E. D. (1881). "A new type of Perissodactyla". American Naturalist. 15 (12): 1017–20. doi:10.1086/272983. OCLC 45953517.
Cope, E. D. (1885). "The Vertebrata of the Tertiary Formations of the West". U. S. Geological Survey of the Territories. 3 (9): 1–1009. doi:10.1017/s0016756800467208. OCLC 3934701. Retrieved April 30, 2013.
Janis, C.M. (1993). "Tertiary Mammal Evolution in the Context of Changing Climates, Vegetation, and Tectonic Events". Annual Review of Ecology and Systematics. 24: 467–500. doi:10.1146/annurev.es.24.110193.002343.
Madsen, O.; Scally, M.; Douady, C.J.; Kao, D.; DeBry, R.W.; Adkins, R.; Amrine, H.M.; Stanhope, M.J.; de Jong, W.W.; Springer, M.S. (2001). "Parallel adaptive radiations in two major clades of placental mammals". Nature. 409 (6820): 610–614. Bibcode:2001Natur.409..610M. doi:10.1038/35054544. PMID 11214318. S2CID 4398233.
McKenna, M.C.; Bell, S.K. (1997). Classification of Mammals Above the Species Level. Columbia University Press. ISBN 978-0-231-11012-9.
Murphy, W.J.; Eizirik, E.; O'Brien, S.J.; Madsen, O.; Scally, M.; Douady, C.J.; Teeling, E.C.; Ryder, O.A.; Stanhope, M.J.; de Jong, W.W.; Springer, M.S. (2001). "Resolution of the early placental mammal radiation using Bayesian phylogenetics". Science. 294 (5550): 2348–2351. Bibcode:2001Sci...294.2348M. doi:10.1126/science.1067179. PMID 11743200. S2CID 34367609.
Novacek, M.J. (1986). "The skull of leptictid insectivorans and the higher-level classification of eutherian mammals". Bulletin of the American Museum of Natural History. 183 (1): 1–111. hdl:2246/1628.
Prothero, D.R.; Manning, E.M.; Fischer, M. (1988). "The phylogeny of the ungulates" (PDF). In Benton, M. J. (ed.). The phylogeny and classification of the tetrapods. 2: mammals. Systematics Association Special Volume 35B. Oxford: Clarendon Press. pp. 201–234. ISBN 9780198577126. Retrieved May 1, 2013.
Thewissen, J.G.M. (1990). Evolution of Paleocene and Eocene Phenacodontidae (Mammalia, Condylarthra). Papers on Paleontology. Vol. 29. Museum of Paleontology, The University of Michigan. hdl:2027.42/48629. OCLC 742731818.
Van Valen, L.M. (1966). "Deltatheridia, a new order of mammals". Bulletin of the American Museum of Natural History. 132 (1): 1–126. hdl:2246/1126.
Van Valen, L.M. (1988). "Paleocene dinosaurs or Cretaceous ungulates in South America?". Evolutionary Monographs. 10: 1–79.
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