Hegetotherium

Hegetotherium
Temporal range: Early-Middle Miocene (Colhuehuapian-Colloncuran)
~21–15.5 Ma
Skull of Hegetotherium mirabile
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: †Notoungulata
Family: †Hegetotheriidae
Subfamily: †Hegetotheriinae
Genus: †Hegetotherium
Ameghino 1887
Species
  • H. mirabile Ameghino 1887 (type)
  • H. cerdasensis Croft et al. 2016

Hegetotherium is a small to middle-sized extinct genus of mammals, ranging from the size of rabbit (about 20-30 cm/12-16") to a beaver (about 3 ft/1 m) from the Early to Middle Miocene (Colhuehuapian-Colloncuran in the SALMA classification), through Pliocene sites of South America. Fossils of this genus have been found in the Cerro Bandera, Cerro Boleadoras, Chichinales, Collón Curá, Santa Cruz and Sarmiento Formations of Argentina, the Nazareno Formation of Bolivia, and the Galera and Río Frías Formations of Chile.

Taxonomy

Hegetotherium is currently restricted to the type species, H. mirable, of which H. convexum, H. anceps, H. minum and H. andinum are synonyms, but also H. cerdasensis. "Hegetotherium" arctum was formerly assigned to this genus, but is clearly not a member of Hegetotheriidae. "Hegetotherium" novum was formerly referred to the closely related genus Prohegetotherium, but is now considered generically distinct from that genus. Historically, it was believed that Hegetotherium persisted to the Pliocene, though the specimens formerly attributed to Hegetotherium from the Pliocene more likely belong to other hegetotheriid genera, such as Hemihegetotherium.

Description

Life restoration of Hegetotherium

In Hegetotherium, as in other hegetotheriids, the internal carotid artery travelled along the basicranial keel in an enclosed osseous canal.

Hegetotheres are characterised by enlarged first upper incisors, implanted obliquely in the premaxilla. Their lower teeth have a straight lingual face. They were among the most recently diverging families of typothere notoungulates, with their early fossil record closely resembling mesotheriids. The hegetotheres, belonging to notoungulate group, have hypselodont (ever-growing) teeth. They reportedly have enlarged first upper incisors that are obliquely implanted in the prexamilla and lower teeth with a straight lingual face.

Palaeobiology

Palaeoecology

The hypselodont teeth indicate of hegetotheriids has been interpreted to mean that they ate low-growing vegetables in open habitats. However, the cranial anatomy of Hegetotherium is indicative of a "mammalian woodpecker" ecology, suggesting that it used its jaws to break through wood to feed on xylophagous grubs and insects within fallen logs. Unlike other mammalian woodpeckers, such as Daubentonia, Dactylopsila, and Yalkaparidon, Hegetotherium was a diurnal, cursorial animal. According to a principal component analysis of the proximal articular surface of the ulna of H. mirabile, the species was neither specialised for climbing nor for digging.

References

  1. ↑ Kramarz, Alejandro Gustavo; Paz, Ernesto Rodrigo (2013). "Un Hegetotheriidae (Mammalia, Notoungulata) basal del Mioceno temprano de Patagonia". Revista Mexicana de Ciencias Geológicas (in Spanish). 30 (1): 186–195. ISSN 1026-8774.
  2. ↑ Vizcaino, Sergio F.; Bargo, M. Susana; Pérez, M. Encarnación; Aramendía, Inés; Cuitiño, José I.; Monsalvo, Eduardo S.; Vlachos, Evangelos; Noriega, Jorge I.; Kay, Richard F. (30 September 2022). "Fossil vertebrates of the early-middle Miocene Cerro Boleadoras Formation, northwestern Santa Cruz Province, Patagonia, Argentina". Andean Geology. 49 (3): 382–422. doi:10.5027/andgeoV49n3-3425. ISSN 0718-7106.
  3. ↑ Barrio, Claudio; Carlini, Alfredo A.; Goin, Francisco J. (1989). "Litogénesis y antigüedad de la Formación Chichinales de Paso Córdoba (Río Negro, Argentina)". Actas, IV Congreso Argentino de Paleontología y Bioestratigrafía, Mendoza. 4: 149–156.
  4. ↑ Federico L. Agnolin and Pablo Chafrat (2015). "New fossil bird remains from the Chichinales Formation (Early Miocene) of northern Patagonia, Argentina". Annales de Paléontologie. 101 (2): 87–94. Bibcode:2015AnPal.101...87A. doi:10.1016/j.annpal.2015.02.001.
  5. ↑ Cuitiño, José I.; Vizcaíno, Sergio F.; Bargo, M. Susana; Aramendía, Inés (31 May 2019). "Sedimentology and fossil vertebrates of the Santa Cruz Formation (early Miocene) in Lago Posadas, southwestern Patagonia, Argentina". Andean Geology. 46 (2): 383–420. doi:10.5027/andgeoV46n2-3128. hdl:11336/96343. ISSN 0718-7106.
  6. ↑ Zurita-Altamirano, Daniel; Buffetaut, Eric; Forasiepi, Analía M.; Kramarz, Alejandro; Carrillo, Juan D.; Aguirre-Fernández, Gabriel; Carlini, Alfredo A.; Scheyer, Torsten M.; Sánchez-Villagra, Marcelo R. (2019). "The Allemann collection from the Santa Cruz Formation (late early Miocene), Argentina, in Zurich, Switzerland". Swiss Journal of Palaeontology. 138 (2): 259–275. Bibcode:2019SwJP..138..259Z. doi:10.1007/s13358-019-00185-5. hdl:11336/120785. ISSN 1664-2384.
  7. ↑ Croft, Darin A.; Carlini, Alfredo A.; Ciancio, MartÍn R.; Brandoni, Diego; Drew, Nicholas E.; Engelman, Russell K.; Anaya, Federico (2 September 2016). "New mammal faunal data from Cerdas, Bolivia, a middle-latitude Neotropical site that chronicles the end of the Middle Miocene Climatic Optimum in South America". Journal of Vertebrate Paleontology. 36 (5) e1163574. Bibcode:2016JVPal..36E3574C. doi:10.1080/02724634.2016.1163574. hdl:11336/49745. ISSN 0272-4634. S2CID 87802865.
  8. ↑ Flynn, John J.; Novacek, Michael J.; Dodson, Holly E.; Frassinetti, Daniel; McKenna, Malcolm C.; Norell, Mark A.; Sears, Karen E.; Swisher, Carl C.; Wyss, André R. (1 July 2002). "A new fossil mammal assemblage from the southern Chilean Andes: implications for geology, geochronology, and tectonics". Journal of South American Earth Sciences. 15 (3): 285–302. Bibcode:2002JSAES..15..285F. doi:10.1016/S0895-9811(02)00043-3. ISSN 0895-9811.
  9. ↑ F. D. Seoane, S. R. Juñent, and E. Cerdeño. 2017. Phylogeny and paleobiogeography of Hegetotheriidae (Mammalia, Notoungulata). Journal of Vertebrate Paleontology 37(1):e1278547:1-13.
  10. ↑ Seoane, Federico Damián; Cerdeño, Esperanza (2 October 2019). "Systematic revision of Hegetotherium and Pachyrukhos (Hegetotheriidae, Notoungulata) and a new phylogenetic analysis of Hegetotheriidae". Journal of Systematic Palaeontology. 17 (19): 1635–1663. Bibcode:2019JSPal..17.1635S. doi:10.1080/14772019.2018.1545146. ISSN 1477-2019. S2CID 92218443.
  11. ↑ Scott, William Berryman; Scott, William Berryman (1913). A history of land mammals in the Western Hemisphere; illustrated with 32 plates and more than 100 drawings. New York: Macmillan.
  12. ↑ MacPhee, Ross D. E.; Forasiepi, Analia M. (15 March 2022). "Re-Evaluating Cranial Pathways of the Internal Carotid Artery in Notoungulata (Mammalia, Panperissodactyla)". Ameghiniana. 59 (2). doi:10.5710/AMGH.06.12.2021.3465. hdl:11336/202788. ISSN 0002-7014. Retrieved 2 November 2025 – via BioOne Digital Library.
  13. ↑ "Hegetotheriidae: Darin A. Croft, PhD". Retrieved 2025-01-25.
  14. ↑ "Hegetotheriidae: Darin A. Croft, PhD". Retrieved 2025-01-25.
  15. ↑ Vizcaíno, Sergio F.; Kay, Richard F.; Bargo, M. Susana (2012). Early Miocene paleobiology in Patagonia: high-latitude paleocommunities of the Santa Cruz Formation. Cambridge New York: Cambridge University Press. ISBN 978-0-521-19461-7.
  16. ↑ McCoy, Dakota E.; Norris, Christopher A. (1 October 2012). "The Cranial Anatomy of the Miocene Notoungulate Hegetotherium mirabile (Notoungulata, Hegetotheriidae) with Preliminary Observations on Diet and Method of Feeding". Bulletin of the Peabody Museum of Natural History. 53 (2): 355–374. doi:10.3374/014.053.0202. ISSN 0079-032X. Retrieved 6 November 2025 – via BioOne Digital Library.
  17. ↑ Muñoz, Nahuel A.; Cassini, Guillermo H.; Candela, Adriana M.; Vizcaíno, Sergio F. (December 2015). "Ulnar articular surface 3-D landmarks and ecomorphology of small mammals: a case study of two early Miocene typotheres (Notoungulata) from Patagonia". Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 106 (4): 315–323. doi:10.1017/S1755691016000141. hdl:11336/56433. ISSN 1755-6910. Retrieved 17 November 2025 – via Cambridge Core.