Xenastrapotherium

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 (named after the Greek word xenos "strange" add to the genus Astrapotherium, "lightning beast") 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.[3]

Xenastrapotherium
Temporal range: Mid-Late Miocene (Friasian-Huayquerian)
~16–6.8 Ma
Xenastrapotherium kraglievichi.jpg
Mandible of X. kraglievichi, Honda Group, Colombia
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Astrapotheria
Family: Astrapotheriidae
Subfamily: Uruguaytheriinae
Genus: Xenastrapotherium
Kraglievich, 1928
Type species
Xenastrapotherium christi
(Stelin, 1928)
Species

See text

Synonyms
  • Astrapotherium christi Stehlin 1928[1]
  • Synastrapotherium Paula Couto 1976[2]

SpeciesEdit

Several species of Xenastrapotherium have been described, although none is known from complete remains; they are distinguished by features of their teeth and jaws, and their geographical and temporal distribution. The species currently recognized are:

  • X. christi Stehlin 1929: the first known species, originally classified by Stehlin (1929) as Astrapotherium christi, and later reclassified to the current genus.[4] It was found in Venezuela near Zaraza in the state of Guarico, based on a full lower jaw.[5]
  • X. kraglievichi Cabrera 1929: based on several teeth and some jaws, discovered in the area of La Venta (Group Honda, Villavieja Formation) in the department of Huila, Colombia, dating from the middle Miocene, about 13 to 11 million years. Distinguished by their lower tusks, which were more horizontal and rounded in cross-section.[6] This species was contemporary with its great relative, Granastrapotherium.
  • X. aequatorialis Johnson & Madden 1997: Based on a piece of right lower jaw, found in the river Burgaya in the province of Cañar, Ecuador, in the Biblián Formation (Middle Miocene, 19 million years ago). It is distinguished by its molar with buccal and labial cingulum, and the first molar was lophodont and had roots. This species is older than the fossils of La Venta, contemporary with Astrapotheriinae like Astrapotherium, Astrapothericulus and Parastrapotherium.[3]
  • X. chaparralensis Johnson & Madden 1997: Another species known from Colombia, was found near to Chaparral in department of Tolima, in the Tuné Formation (early Miocene). It is distinguished by its greater molar area, a high molar buccal cingulum, with canines very similar to those of X. kraglievichi.[3]
  • X. amazonense Paula Couto 1976: Based on jaw fragments found in the vicinity of the river Breu, Pedra Pintada, Brazil, also found in the Fitzcarrald Arch in Peru. It is distinguished by the large size of the third molar, compared to other species of Xenastrapotherium. It was classified originally in its own genus, Synastrapotherium.[7] A tusk assigned to this species was found in the zone of Acre in Brazil, in deposits from the late Miocene, which make it the most recent record for the astrapotheres;[8] but this idea has been challenged, since the fossil could not be from an astrapothere.[9]

PhylogenyEdit

Cladogram based in the phylogenetic analysis published by Vallejo Pareja et al., 2015, showing the position of Xenastrapotherium:[10]

Eoastrapostylops

Trigonostylops

Tetragonostylops

Albertogaudrya

Scaglia

Astraponotus

Maddenia

Comahuetherium

Parastrapotherium

Astrapotheriinae

Astrapotherium

Astrapothericulus

Uruguaytheriinae

Uruguaytherium

Hilarcotherium

Xenastrapotherium

Granastrapotherium

DistributionEdit

Fossils of Xenastrapotherium have been found in:[2]

ReferencesEdit

  1. ^ Astrapotherium christi at Fossilworks.org
  2. ^ a b Xenastrapotherium at Fossilworks.org
  3. ^ a b c Johnson, S. C. & Madden, R. H. 1997. Uruguaytheriine astrapotheres of tropical South America. In Kay, R. F., Madden, R. H., Cifelli, R. L. & Flynn, J. J. (eds) Vertebrate Paleontology in the Neotropics: The Miocene fauna of La Venta, Colombia. Smithsonian Institution Press (Washington, D.C.), pp. 355-381.
  4. ^ Kraglievich, L. 1928. Sobre el supuesto Astrapotherium christi Stehlin descubierto en Venezuela (Xenastrapotherium n. gen.) y sus relaciones con Astrapotherium magnum y Uruguaytherium beaulieui. Buenos Aires, Franco.
  5. ^ Stehlin H (1928). "Ein Astrapotherium fund aus Venezuela". Eclogae Geol. Helvetiae. 21: 227–232.
  6. ^ Cabrera, A, 1929. Un Astrapotherido de Colombia, Rev. Soc. Argentina Cienc. Nat., t. 9, pp. 436-439, 3 fig., Buenos Aires.
  7. ^ Paula Couto C (1974). "Fossil mammals from the Cenozoic of Acre, Brazil. 1 - Astrapotheria". Congresso Brasileiro de Geologia. 2: 237–249.
  8. ^ Frailey C. D. 1986. — Late Miocene and Holocene mammals, exclusive of the Notoungulata, of the Rio Acre region, western Amazonia. Contributions in Science, Natural History Museum of Los Angeles County 374: 1–46.
  9. ^ Goillot Cyrielle, Antoine Pierre-Olivier, Tejada Julia, Pujos François (2011). "Middle Miocene Uruguaytheriinae (Mammalia, Astrapotheria) from Peruvian Amazonia and a review of the astrapotheriid fossil record in northern South America". Geodiversitas. 33 (2): 331–345. doi:10.5252/g2011n2a8. S2CID 129460591.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  10. ^ M. C. Vallejo Pareja, J. D. Carrillo, J. W. Moreno Bernal, M. Pardo Jaramillo, D. F. Rodríguez González and J. Muñoz Duran (2015). "Hilarcotherium castanedaii, gen. et sp. nov., a new Miocene astrapothere (Mammalia, Astrapotheriidae) from the Upper Magdalena Valley, Colombia" (PDF). Journal of Vertebrate Paleontology. 35 (2): e903960. doi:10.1080/02724634.2014.903960. S2CID 130728894.{{cite journal}}: CS1 maint: multiple names: authors list (link)

External linksEdit