Miocochilius

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Miocochilius
Temporal range: Mid Miocene (Laventan)
~13.8–11.8  Ma
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Miocochilius anomopodus - skeleton - Honda Group - Colombia.jpg
Reconstructed skeleton of Miocochilius anomopodus.
Exhibit in the Museo Paleontológico José Royo y Gómez, Bogotá, Colombia
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Notoungulata
Family: Interatheriidae
Subfamily: Interatheriinae
Genus: Miocochilius
Stirton 1953
Type species
Miocochilius anamopodus
Stirton 1953
Species
  • M. anomopodusStirton 1953 (type)
  • M. federicoi Croft 2007

Miocochilius is an extinct genus of small notoungulate mammals (typotheres) native to South America. The genus lived during the Middle Miocene epoch (Laventan in the SALMA classification). The genus contains two described species, the type species M. anomopodus described in 1953 by Ruben Arthur Stirton and M. federicoi, described and included in the genus by Darin A. Croft.

Contents

Fossils of Miocochilius have been found at the Lagerstätte of La Venta in the Honda Group of Colombia, where it is the most abundant mammal, the Honda Group of Bolivia (M. federicoi) and the Ipururo Formation in the Ucayali Basin of Peru. The typothere lived alongside a rich faunal assemblage comprising many other mammals, crocodylians, turtles and lizards.

Description

Manus and pes of Miocochilius Miocochilius anomopodus.jpg
Manus and pes of Miocochilius
South America laea relief location map.jpg
Yellow pog.svg
Green pog.svg
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Miocochilius fossils in South America
Yellow pog.svg Colombia (M. anapomodus)
Red pog.svg Peru (M. anapomodus)
Green pog.svg Bolivia (M. federicoi)

The genus Miocochilius was first described by Ruben Arthur Stirton in 1953, based on a nearly complete and numerous incomplete skeletons found in the Honda Group of Colombia. [1] [2] The type species was named M. anomopodus. More fossils of this species were found at La Venta and in the Ipururo Formation in Peru. [3]

The holotype specimen of the small typothere, a cursorial insectivore, had a cerebral hemisphere length of 38 millimetres (1.5 in), canines of 5.5 by 3.0 millimetres (0.22 in × 0.12 in) and a cheekbone of 43.0 by 6.0 millimetres (1.69 in × 0.24 in). The premaxilla measured 6.0 millimetres (0.24 in). [3]

A second species, M. federicoi, was described by Darin A. Croft in 2007 based on a maxilla found in the Honda Group of Bolivia. [4] The species epithet refers to Federico Anaya, a scientist and field collector who has been instrumental in advancing vertebrate paleontology in Bolivia. M. federicoi differs from Eopachyrucos , Santiagorothia , Proargyrohyrax , Archaeophylus and Progaleopithecus in having extremely high crowned teeth. The described species is differentiated from the Chasicoan to Colloncuran genus Protypotherium in having more open lingual enamel folds, variable presence of small median lobe on upper molars, and molars with more rounded distal lobes. The species also is different than Argyrohyrax in the absence of fossettes on the upper molars. Compared to Cochilius and the Colloncuran Interatherium , Miocochilius federicoi has a longer, low skull. [5] The author inclined to describe the specimen as a separate genus, but finally included the species in Miocochilius. [6]

Paleoecology

Miocochilius shared its habitat with many other mammals, birds, reptiles and amphibians. The Colombian specimens were found in fluvial claystones of the "Monkey Unit", El Líbano sands and clays, San Nicolas Unit, Upper Red Bed and the Baraya Volcanic Member of the Villavieja Formation and the Cerro Gordo Member of the La Victoria Formation of the Honda Group. Fossils of Miocochilius, the most abundant mammal at La Venta, [5] were found alongside the primates Mohanamico hershkovitzi , Neosaimiri fieldsi and Stirtonia tatacoensis , the rodents Scleromys colombianus , S. schurmanni , Drytomomys aequatorialis , Neoreomys huilensis , Eodolichotis maddeni , Rhodanodolichotis antepridiana , Prodolichotis guerreroi and P. pridiana , the ant eater Neotamandua borealis , the bat Notonycteris magdalenensis , the pampatheriid Scirrotherium hondaensis , other notoungulates Pericotoxodon platignathus , Huilatherium pluripicatum , the sea cow Potamosiren magdalenensis , the sparassodonts Hondadelphys fieldsi and Lycopsis longirostrus , the litoptern Megadolodus molariformis and the ground sloth Magdalenabradys confusum . The assemblage also contained the crocodylians Purussaurus neivensis and Charactosuchus fieldsi , the caiman lizard Dracaena colombiana , and the turtles Geochelone and Podocnemis pritchardi . [7] [8] [9] [10] [11] [12] [13] [14]

The fossils belong to the Xenastrapotherium kraglievichi - Granastrapotherium snorki assemblage at La Venta. [15] Based on vegetational and grazer diversity analysis of the La Venta fauna, it has been suggested the ecosystem resembled more that of Africa and Asia than of the modern Neotropics. [16]

The Peruvian specimen was collected in a conglomerate, deposited in a storm-dominated coastal to fluvial environment, alternatively described as lacustrine and paludal, [17] at the Fitzcarrald Arch in the Ucayali River basin of Amazonian Peru. [18] Other mammals found in the same location were the toxodont Pericotoxodon cf. platignathus , glyptodonts Boreostemma and Parapropalaehoplophorus septentrionalis , the ground sloth Urumacotherium and rodent Drytomomys cf. aequatorialis . [19]

The Bolivian species M. federicoi was discovered in fluvial silty claystones of the Honda Group, dated on the basis of 40K/40Ar analysis at 12.83 ± 0.11 Ma and 11.96 ± 0.11 Ma. The fossil was accompanied by a large variety of rodents, sparassodonts, litopterns, notoungulates and the glyptodonts Hapalops angustipalatus , Hiskatherium saintandrei and Propalaehoplophorus andinus . [20] In total, 30 different genera of mammals are described from the Quebrada Honda fauna, while 68 genera were described at La Venta. [21] [22]

See also

Related Research Articles

<i>Hapalops</i> Extinct genus of ground sloths

Hapalops is an extinct genus of ground sloth from the Early to Late Miocene of Brazil, Bolivia, Colombia, and Argentina in South America.

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

Theosodon is an extinct genus of litoptern mammal from the Early to Middle Miocene of South America.

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

Xenorhinotherium is an extinct genus of macraucheniine macraucheniids, closely related to Macrauchenia of Patagonia. The type species is X. bahiense.

Stirtonia is an extinct genus of New World monkeys from the Middle Miocene. Its remains have been found at the Konzentrat-Lagerstätte of La Venta in the Honda Group of Colombia. Two species have been described, S. victoriae and the type species S. tatacoensis. Synonyms are Homunculus tatacoensis, described by Ruben Arthur Stirton in 1951 and Kondous laventicus by Setoguchi in 1985. The genus is classified in Alouattini as an ancestor to the modern howler monkeys.

The Laventan age is a period of geologic time within the Middle Miocene epoch of the Neogene, used more specifically within the SALMA classification in South America. It follows the Colloncuran and precedes the Mayoan age.

<i>Xenastrapotherium</i>

Xenastrapotherium is an extinct genus of astrapothere, a type of hoofed herbivorous mammal, native to South America, which lived in the Middle to Late Miocene period, typically during the Laventan stage. It is a member of the family Astrapotheriidae in the subfamily Uruguaytheriinae, large astrapotheres, equipped with a trunk-like nose and protruding teeth, similar to the elephants, but their tusks were the canine teeth, not the incisors. Xenastrapotherium was a genus widely distributed in northern South America, in contrast to other species of astrapotheres which lived in the area of the Southern Cone of the continent. It differed from other astrapotheres by having two lower incisors on each side of the jaw and the tusks have a pronounced longitudinal curvature, although their general shape and size are probably very similar to Astrapotherium, whose weight would be 900 to 1,500 kilograms, comparable to the current black rhinoceros.

<span class="mw-page-title-main">Honda Group, Colombia</span> Geological group in the Colombian Andes

The Honda Group is a geological group of the Upper and Middle Magdalena Basins and the adjacent Central and Eastern Ranges of the Colombian Andes. The group, in older literature also defined as formation, is in its present-day type section in the Tatacoa Desert in the department of Huila subdivided into two main formations; La Victoria and Villavieja.

Lagonimico is an extinct genus of New World monkeys from the Middle Miocene. Its remains have been found at the Konzentrat-Lagerstätte of La Venta in the Honda Group of Colombia. The type species is L. conclucatus.

Saimiri annectens, originally described as Laventiana annectens and later as Neosaimiri annectens, is an extinct species of New World monkey in the genus Saimiri from the Middle Miocene. Its remains have been found at the Konzentrat-Lagerstätte of La Venta in the Honda Group of Colombia.

Saimiri fieldsi is an extinct species of New World monkey in the genus Saimiri from the Middle Miocene. Its remains have been found at the Konzentrat-Lagerstätte of La Venta in the Honda Group of Colombia.

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

Boreostemma is an extinct genus of glyptodonts from northern South America. Fossils assigned to the genus were first described as belonging to Asterostemma from southern South America, but have been placed in the new genus Boreostemma by Carlini et al. in 2008. The type species is B. pliocena. Fossils of Boreostemma have been found in the Honda Group of Colombia, in Peru and Venezuela.

Canaanimico is an extinct genus of medium-sized New World monkeys from the Late Oligocene fossiliferous fluvio-lacustrine Chambira Formation of the Ucayali Basin in Amazonian Peru. The genus was described by Marivaux et al. in 2016 and the type species is C. amazonensis.

Paradracaena is an extinct genus of lizards from northern South America. Fossils of Paradracaena colombiana have been found in the Honda Group of Colombia, Peru and Brazil. The species was described as a member of the tegus; Tupinambis huilensis by Estes in 1961.

Paratrigodon is a extinct genus notoungulate belonging to the subfamily Toxodontinae, containing one species, P. euguii. Like its close relative Trigodon, it is known for the presence of a horn-like protuberance on its forehead. Fossils of Paratrigodon are known from the Arroyo Chasicó Formation dating from the Chasicoan period, and teeth from the Laventan-aged Quebrada Honda Fauna of Bolivia were also associated with the genus, although considered too different from the type species to be assigned to it.

Proterotherium is an extinct genus of litoptern mammal of the family Proterotheriidae that lived during the Late Miocene of Argentina and Chile. Fossils of this genus have been found in the Ituzaingó Formation of Argentina, and the Galera Formation of Chile.

Promacrauchenia is an extinct genus of macraucheniids that lived during the Late Miocene to Late Pliocene epochs of what is now Argentina and Bolivia. It belongs to the subfamily Macraucheniinae, which also includes Huayqueriana, Macrauchenia, and Xenorhinotherium. Fossils of this genus have been found in the Ituzaingó, Andalhuala, and Cerro Azul Formations of Argentina.

Megadolodus is an extinct genus of proterotheriid litopterns.

Prolicaphrium is an extinct genus of proterotheriid litoptern that lived during the Early Miocene, in what is now Argentina. Fossils have been found in the Sarmiento Formation of Argentina.

Juchuysillu is an extinct genus of interatheriid notoungulate. It lived from the Early to the Middle Miocene, and its fossils have been found in Bolivia.

References

  1. Miocochilius at Fossilworks.org
  2. Stirton, 1953, p.265
  3. 1 2 Miocochilius anomopodus at Fossilworks.org
  4. Miocochilius federicoi at Fossilworks.org
  5. 1 2 Croft, 2007, p.283
  6. Croft, 2007, p.284
  7. Interathere locality at Fossilworks.org
  8. Baraya Volcanic Member at Fossilworks.org
  9. El Líbano sands and clays at Fossilworks.org
  10. Monkey Unit at Fossilworks.org
  11. Upper Red Bed at Fossilworks.org
  12. Lone Tree locality at Fossilworks.org
  13. Cerro Gordo at Fossilworks.org
  14. Toxodont locality at Fossilworks.org
  15. Goillot et al., 2011, p.339
  16. Kay & Madden, 1997, p.183
  17. Castro Medina, 2010, p.58
  18. Antoine, 2016, p.35
  19. IN-DTC-32, Ipururo Formation at Fossilworks.org
  20. Quebrada Honda fauna at Fossilworks.org
  21. Croft, 2007, p.287
  22. Croft, 2007, p.290

Bibliography