Xenungulata

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Xenungulata
Temporal range: Late Paleocene-Early Eocene
(Riochican-Casamayoran)
~58.6–48.7  Ma
Carodnia vieirai.JPG
Interpretation of Carodnia vieirai
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Placentalia
Clade: Meridiungulata
Order: Xenungulata
Paula Couto 1952
Family and genera [1]

Xenungulata ("strange ungulates") is an order of extinct and primitive South American hoofed mammals that lived from the Late Paleocene to Early Eocene (Itaboraian to Casamayoran in the SALMA classification). Fossils of the order are known from deposits in Brazil, Argentina, Peru, [4] and Colombia. The best known member of this enigmatic order is the genus Carodnia , a tapir-like and -sized animal with a gait similar to living African elephants. [5]

Contents

Description

Xenungulates are characterized by bilophodont M1–2 and M1–2, similar to pyrotheres, and complex lophate third molars, similar to uintatheres. Though other relationships, to arctocyonids for example, have been suggested, no proofs thereof have been found. The foot bones of xenungulates were short and robust and their digits terminated in broad, flat, and unfissured hoof-like unguals, quite unlike any other meridiungulates. The discovery of Etayoa in Colombia [6] made it clear that xenungulates are distinct from other groups: Etayoa lacks lophate molar talonid (in contrast to Carodnia) and, since no distinct lophodonty is present in basal pyrotheres, there is reason to assume that bilophodonty evolved separately in xenungulates and pyrotheres. Xenungulates also show some dental similarity to primitive astrapotheres. [7]

Taxonomy

Cifelli 1983 grouped Carodnia with pyrotheres based on a similarity in astragalus morphology, but later concluded that this observation was incorrect. [8]

Notoetayoa is most closely related to Etayoa. [9]

Distribution

Xenungulata fossils have been found in: [10]

Related Research Articles

<span class="mw-page-title-main">Notoungulata</span> Extinct order of hoofed mammals

Notoungulata is an extinct order of ungulates that inhabited South America from the early Paleocene to the end of the Pleistocene, living from approximately 61 million to 11,000 years ago. Notoungulates were morphologically diverse, with forms resembling animals as disparate as rabbits and rhinoceroses. Notoungulata are the largest group of South American native ungulates, with over 150 genera in 14 families having been described, divided into two major subgroupings, Typotheria and Toxodontia. Notoungulates first diversified during the Eocene. Their diversity declined from the late Neogene onwards, with only the large toxodontids persisting until the end of the Pleistocene, perishing as part of the Late Pleistocene megafauna extinctions along with most other large mammals across the Americas. Collagen sequence analysis suggests that notoungulates are closely related to litopterns, another group of South American ungulates, and their closest living relatives being perissodactyls, including rhinoceroses, tapirs and equines as part of the clade Panperissodactyla. However their relationships to other South American ungulates are uncertain. Several groups of notoungulates separately evolved ever-growing cheek teeth.

<span class="mw-page-title-main">South American native ungulates</span> Extinct clade of mammals

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 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 of the largest 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.

<span class="mw-page-title-main">Pyrotheria</span> Extinct order of mammals

Pyrotheria is an order of extinct meridiungulate mammals. These elephant-like ungulates include the genera Baguatherium, Carolozittelia, Colombitherium, Griphodon, Propyrotherium, Proticia, and Pyrotherium.

<i>Trigonostylops</i> Genus of mammals (fossil)

Trigonostylops is an extinct genus of South American meridiungulatan ungulate, from the Late Paleocene to Late Eocene of South America and Antarctica. It is the only member of the family Trigonostylopidae.

Victorlemoinea is an extinct litoptern genus of the family Sparnotheriodontidae, that lived from the Early to Middle Eocene. Fossils of Victorlemoinea have been found in the Las Flores, Sarmiento and Koluel Kaike Formations of Argentina, the Itaboraí Formation of Brazil and La Meseta Formation, Antarctica.

<i>Carodnia</i> Genus of South American hoofed mammals (fossil)

Carodnia is an extinct genus of South American ungulate known from the Early Eocene of Brazil, Argentina, and Peru. Carodnia is placed in the order Xenungulata together with Etayoa and Notoetayoa.

<span class="mw-page-title-main">Astrapotheria</span> Extinct order of mammals

Astrapotheria is an extinct order of South American and Antarctic hoofed mammals that existed from the late Paleocene to the Middle Miocene, 59 to 11.8 million years ago. Astrapotheres were large, rhinoceros-like animals and have been called one of the most bizarre orders of mammals with an enigmatic evolutionary history.

<span class="mw-page-title-main">Itaboraian</span>

The Itaboraian age is a period within the Early Eocene geologic time epoch of the Paleogene, used more specifically with South American land mammal ages (SALMA). It follows the Riochican and precedes the Casamayoran age.

The Riochican age is a period of geologic time within the Paleocene and Eocene epochs of the Paleogene, used more specifically within the South American land mammal ages (SALMA). It follows the Peligran and precedes the Itaboraian age.

<i>Etayoa</i> Extinct genus of mammals

Etayoa is an ungulate of the family Carodniidae in the order Xenungulata that lived during the Early Eocene in northern South America.

The Río Loro Formation is a geological formation of the Sierras Pampeanas in Tucumán Province Argentina whose strata date back to the Late Paleocene of the Paleogene, or Riochican in the SALMA classification.

Ernestokokenia is an extinct genus of mammal, belonging to the Didolodontidae. It lived during the Early Eocene and the Middle Eocene, and its fossils were discovered in South America.

Lamegoia is an extinct genus of mammals, belonging to the family Didolodontidae. It contains a single species, Lamegoia conodonta, which lived during the Late Paleocene in what is now South America.

Paulogervaisia is an extinct genus of mammal, belonging to the family Didolodontidae. Its fossilized remains have been found in South America.

Notoetayoa is an extinct genus of mammal, from the order Xenungulata. It contains a single species, Notoetayoa gargantuai, which lived during the Middle Paleocene. Its fossilized remains were discovered in South America.

Rodcania is an extinct genus of mammal, belonging to the order Xenungulata. It contains a single species, Rodcania kakan, which lived during the Paleocene. Its remains were found in South America. The genus name is an anagram of Carodnia.

Sparnotheriodontidae is an enigmatic extinct family of litopterns known primarily from teeth. Sparnotheriodontids are one of two South American native ungulate clades known to have reached Antarctica, the other being astrapotheres.

Protolipterna is an extinct genus of mammal, belonging to the order Litopterna. It lived during the Late Paleocene and the Early Eocene, in what is now South America.

<i>Anisolambda</i> Extinct genus of litopterns

Anisolambda is an extinct genus of litoptern. It lived from the Late Paleocene to the Middle Eocene in what is now Argentina.

Sparnotheriodon is an extinct genus of sparnotheriodontid litoptern that lived during the Middle Eocene of what is now Argentina, leaving fossils in the Sarmiento Formation.

References

  1. "Xenungulata". Palaeocritti. Retrieved 4 May 2013.
  2. Carodniidae in the Paleobiology Database. Retrieved May 2013.
  3. Gelfo, Javier N.; García-López, Daniel A.; Bergqvist, Lilian P. (2020). "Phylogenetic relationships and palaeobiology of a new xenungulate (Mammalia: Eutheria) from the Palaeogene of Argentina". Journal of Systematic Palaeontology. 18 (12): 993–1007. doi:10.1080/14772019.2020.1715496. S2CID   213052956.
  4. Antoine et al. 2015
  5. Fariña, Vizcaíno & De Iuliis 2013 , p. 86
  6. Villarroel 1987
  7. Rose 2006 , Xenungulata, p. 238
  8. Gingerich 1985 , p. 131
  9. Gelfo, López & Bond 2008 , Abstract
  10. Xenungulata at Fossilworks.org

Bibliography