Teleoceras

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Teleoceras
Temporal range: Barstovian-Blancan
~15.97–4.5  Ma
Natural History Museum of LA Teleoceras.jpg
Specimen at the Natural History Museum of LA
Teleoceras Horsfall.jpg
1913 T. fossiger illustration by Robert Bruce Horsfall.
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Perissodactyla
Family: Rhinocerotidae
Subfamily: Aceratheriinae
Genus: Teleoceras
Hatcher, 1894
Type species
Teleoceras major
Species [1]
  • T. aepysoma
  • T. aginense
  • T. americanum
  • T. brachyrhinum
  • T. hicksi
  • T. fossiger
  • T. guymonense
  • T. major
  • T. medicornutum
  • T. meridianum
  • T. proterum
Synonyms
  • Mesoceras(Cook, 1930) [2]
  • ParaphelopsLane, 1927 [3]

Teleoceras is an extinct genus of rhinocerotid endemic to North America during the Neogene (Miocene and Pliocene).

Contents

Taxonomy

Teleoceras is derived from Greek: "perfect" (teleos) & "horn" (keratos). [4]

Description

Teleoceras had much shorter legs than modern rhinos, and a barrel chest, making its build more like that of a hippopotamus than a modern rhino. It grew up to lengths of 13 feet (4.0 meters) long. [5] T. major was found to have been sexually dimorphic, with males being larger than females. Based on the most reliable method, non-length longbones, males could’ve weighed 883.3–1,109.7 kg (1,947–2,446 lb), while females were estimated to have weighed 785.1–840.1 kg (1,731–1,852 lb). [6]

Some species of Teleoceras have a small nasal horn, but this appears to be absent in other species such as T. aepysoma. [7]

Skulls
Annales du Musee d'histoire naturelle de Marseille, published aux frais de la ville (1917) (18409149955).jpg
T. aginense
Teleoceras fossiger (fossil rhinoceros) (Miocene; Kansas, USA) 5 (33492625686).jpg
T. fossiger, Kansas.
Teleoceras major (fossil barrel-bodied rhino) skull (Ash Hollow Formation, Miocene, 11.83 Ma; Ashfall Fossil Beds, Nebraska, USA) 4.jpg
Young female T. major, Nebraska.
Baby rhino skull, Teleoceras.jpg
Baby.

Behavior and Paleoecology

Teleoceras has high crowned (hypsodont) molar teeth, which has historically led to suggestions that the species were grazers. Dental microwear and mesowear analysis alternatively suggest a browsing or mixed feeding (both browsing and grazing) diet. [8] [9] Whether or not Teleoceras was semi-aquatic had been debated by experts. Based on this description, Henry Fairfield Osborn suggested in 1898 that it was semi-aquatic and hippo-like in habits, however and oxygen isotope analysis of tooth enamel suggests hippo-like grazing habits, but not aquatic. [6] [10] However, δ18O measurements from Ashfall suggest that the species T. major was semi-aquatic. [11] [12] [13] Further evidence of the dependence on water of T. major comes from combined studies of its enamel 87Sr/86Sr, δ13C, and δ18O, which show its lifetime movement patterns were mostly restricted to areas with high water availability. [14]

Social behavior

Teleoceras was sexually dimorphic. Males were larger, with larger tusks (lower incisors), a more massive head and neck, and significantly larger forelimbs. As a result of bimaturism, females matured and stopped growing before males, which is often seen in extant polygynous mammals. Males may have fought for mating rights; healed wounds on skulls have been observed, and healed broken ribs are not uncommon (although not all have their sexes determined). This is further supported by the breeding age female-to-male ratio in the Ashfall Fossil Beds being 4.25:1. There is also a rarity of young adult males preserved at Ashfall, which may be accounted for if they formed bachelor herds away from females and dominant bulls. [6]

Paleoenvironment

Teleoceras was endemic to North America during the Miocene during the Hemingfordian faunal stage to the end of Hemphillian faunal stage from around 17.5 to 4.9 million years ago, [15] [16] and is considered an index fauna of the Hemphillian. [17] However, several boundary / Blancan faunal stage specimens have been recovered from Pliocene era North America, including the Ringold Formation of Washington, the Beck Ranch fauna of Texas, the Pipe Creek sinkhole fauna of Indiana and the Saw Rock Canyon fauna of Kansas. [17] [18]

The presence of Plionarctos and Teleoceras have been used to constrain the temporal ages of the Gray Fossil Site, Palmetto fauna and Pipe Creek Sinkhole to the Hemphillian (between 7Mya and 4.5Mya, late Miocene to early Pliocene), [19] [20] however specimens of these index fossils younger than 4.5Mya put this temporal bracketing in doubt. [21]

Important sites

Ashfall Fossil Beds

Teleoceras major is the most common fossil in the Ashfall Fossil Beds of Nebraska. Over 100 intact T. major skeletons are preserved in ash from the Bruneau-Jarbidge supervolcanic eruption. Of the 20+ taxa present, T. major was buried above the rest, being the last of the animals to succumb (small animals died faster), several weeks or months after the pyroclastic airfall event. Their skeletons show evidence of bone disease, i.e. hypertrophic pulmonary osteodystrophy (HPOD), as a result of lung failure from the fine volcanic ash. [22]

Most of the skeletons are adult females and young, the breeding age female-to-male ratio being 4.25:1. There is also a rarity of young adult males. If the rhinos at Ashfall represent a herd, this may be accounted for if young adult males formed bachelor herds away from females and dominant bulls. The age demographic is very similar to that of modern hippo herds, as amongst the skeletons, 54% are immature, 30% are young adults, and 16% are older adults. [6]

The greatest concentration of Ashfall fossils is housed in a building called the "Rhino Barn", due to the prevalence of T. major skeletons at the site, of which most were preserved in a nearly complete state. One extraordinary specimen includes the remains of a Teleoceras calf trying to suckle from its mother. [23]

T. major from the Ashfall Fossil Beds
Ashfall Fossil Beds - Teleoceras and Cormohipparion.jpg
(1) 8-9 year old young adult male "Tusker". Wisdom teeth emerging. (2) Cormohipparion occidentale
Ashfall Fossil Beds - Teleoceras female and calf.jpg
(3) Adult female "Sandy" (4) Calf "Justin".
Teleoceras major (fossil barrel-bodied rhino) in fossiliferous volcanic tuff (Ash Hollow Formation, Miocene, 11.83 Ma; Ashfall Fossil Beds, Nebraska, USA) 12.jpg
10-12 year old adult male "Dr. Marie", with all permanent teeth.
Teleoceras major (barrel-bodied rhinos) (Ash Hollow Formation, Miocene, 11.83 Ma; Ashfall Fossil Beds, Nebraska, USA) 2.jpg
Fetus within birth canal of the pelvis.

Gray Fossil Site

The Gray Fossil Site in northeast Tennessee, dated to 4.5-5 million years ago, hosts one of the latest-known populations of Teleoceras,Teleoceras aepysoma. [24]

Extinction

Teleoceras is typically though to have gone extinct in North America (alongside Aphelops ) at the end of the Hemphillian, most likely due to rapid climate cooling, increased seasonality and expansion of C4 grasses, as isotopic evidence suggests that the uptake of C4 plants was far less than that in contemporary horses. [15] However, Blancan age specimens may be younger than 4.5 million years old, and may be as young as 3.5 million years old (although some sites are disputed). [17] [18]

References

  1. Prothero, 2005, p. 94.
  2. McKenna & Bell, 1997, p. 483.
  3. Prothero, 2005, p. 122.
  4. "Glossary. American Museum of Natural History". Archived from the original on 20 November 2021.
  5. "Region 4: The Great Plains". geology.teacherfriendlyguide.org. Retrieved 2021-06-26.
  6. 1 2 3 4 Mead, Alfred J. (2000). "Sexual dimorphism and paleoecology in Teleoceras , a North American Miocene rhinoceros" . Paleobiology. 26 (4): 689–706. Bibcode:2000Pbio...26..689M. doi:10.1666/0094-8373(2000)026<0689:SDAPIT>2.0.CO;2. ISSN   0094-8373.
  7. Short, Rachel; Wallace, Steven; Emmert, Laura (2019-04-27). "A new species of Teleoceras (Mammalia, Rhinocerotidae) from the late Hemphillian of Tennessee". Bulletin of the Florida Museum of Natural History. 56 (5): 183–260. doi:10.58782/flmnh.kpcf8483. ISSN   2373-9991.
  8. Mihlbachler, Matthew C.; Campbell, Daniel; Chen, Charlotte; Ayoub, Michael; Kaur, Pawandeep (February 2018). "Microwear–mesowear congruence and mortality bias in rhinoceros mass-death assemblages" . Paleobiology. 44 (1): 131–154. Bibcode:2018Pbio...44..131M. doi:10.1017/pab.2017.13. ISSN   0094-8373. S2CID   90987376.
  9. Voorhies, M. R.; Thomasson, J. R. (1979-10-19). "Fossil grass anthoecia within miocene rhinoceros skeletons: diet in an extinct species". Science. 206 (4416): 331–333. Bibcode:1979Sci...206..331V. doi:10.1126/science.206.4416.331. ISSN   0036-8075. PMID   17733681.
  10. MacFadden, Bruce J. (1998). "Tale of two Rhinos: Isotopic Ecology, Paleodiet, and Niche Differentiation of Aphelops and Teloceras from the Florida Neogene". Paleobiology. 24 (2): 274–286. doi:10.1666/0094-8373(1998)024[0274:TOTRIE]2.3.CO;2. ISSN   0094-8373. JSTOR   2401243.
  11. Ward, Clark T.; Crowley, Brooke E.; Secord, Ross (15 September 2024). "Home on the range: A multi-isotope investigation of ungulate resource partitioning at Ashfall Fossil Beds, Nebraska, USA". Palaeogeography, Palaeoclimatology, Palaeoecology . 650 112375. Bibcode:2024PPP...65012375W. doi: 10.1016/j.palaeo.2024.112375 .
  12. "Fossil Teeth Of Extinct North American Rhinos Reveal An Aquatic Lifestyle Similar To Modern Hippos". ScienceDaily. Retrieved 2025-02-23.
  13. Wang, Bian; Secord, Ross (2020-03-15). "Paleoecology of Aphelops and Teleoceras (Rhinocerotidae) through an interval of changing climate and vegetation in the Neogene of the Great Plains, central United States" . Palaeogeography, Palaeoclimatology, Palaeoecology. 542 109411. Bibcode:2020PPP...54209411W. doi: 10.1016/j.palaeo.2019.109411 . ISSN   0031-0182.
  14. Ward, Clark T.; Crowley, Brooke E.; Secord, Ross (4 April 2025). "Enamel carbon, oxygen, and strontium isotopes reveal limited mobility in an extinct rhinoceros at Ashfall Fossil Beds, Nebraska, USA". Scientific Reports . 15 (1). doi:10.1038/s41598-025-94263-z. ISSN   2045-2322. PMC   11971351 . PMID   40185810 . Retrieved 10 August 2025 via Springer Nature Link.
  15. 1 2 Wang, B.; Secord, R. (2020). "Paleoecology of Aphelops and Teleoceras (Rhinocerotidae) through an interval of changing climate and vegetation in the Neogene of the Great Plains, central United States". Palaeogeography, Palaeoclimatology, Palaeoecology. 542 109411. Bibcode:2020PPP...54209411W. doi: 10.1016/j.palaeo.2019.109411 .
  16. "The Evolution of North American Rhinoceroses". Cambridge University Press & Assessment. Retrieved 2025-07-16.
  17. 1 2 3 Samuels, Joshua X.; Bredehoeft, Keila E.; Wallace, Steven C. (2018). "A new species of Gulo from the Early Pliocene Gray Fossil Site (Eastern United States); rethinking the evolution of wolverines". PeerJ. 6 e4648. doi: 10.7717/peerj.4648 . ISSN   2167-8359. PMC   5910791 . PMID   29682423.
  18. 1 2 Gustafson, Eric P. (2012-05-01). "New records of rhinoceroses from the Ringold Formation of central Washington and the Hemphillian-Blancan boundary" . Journal of Vertebrate Paleontology. 32 (3): 727–731. Bibcode:2012JVPal..32..727G. doi:10.1080/02724634.2012.658481. ISSN   0272-4634.
  19. Hawkins, Patrick (2011-05-01). "Variation in the Modified First Metatarsal of a Large Sample of Tapirus polkensis and the Functional Implications for Ceratomorphs". Electronic Theses and Dissertations.
  20. Wallace, Steven C.; Wang, Xiaoming (30 September 2004). "Two new carnivores from an unusual late Tertiary forest biota in eastern North America" (PDF). Nature.
  21. Samuels, Joshua X.; Bredehoeft, Keila E.; Wallace, Steven C. (2018). "A new species of Gulo from the Early Pliocene Gray Fossil Site (Eastern United States); rethinking the evolution of wolverines". PeerJ. 6 e4648. doi: 10.7717/peerj.4648 . ISSN   2167-8359. PMC   5910791 . PMID   29682423.
  22. Tucker, S.T.; Otto, R.E.; Joeckel, R.M.; Voorhies, M.R. (April 2014), "The geology and paleontology of Ashfall Fossil Beds, a late Miocene (Clarendonian) mass-death assemblage, Antelope County and adjacent Knox County, Nebraska, USA" , Geologic Field Trips along the Boundary between the Central Lowlands and Great Plains: 2014 Meeting of the GSA North-Central Section, Geological Society of America, pp. 1–22, doi:10.1130/2014.0036(01), ISBN   978-0-8137-0036-6 , retrieved 2024-08-13
  23. "Ashfall Fossil Beds". Archived from the original on 2011-05-18. Retrieved 2005-12-13.
  24. Short, Rachel A; Wallace, Steven C. "A New Species of Teleoceras (Mammalia, Rhinocerotidae) from the Late Hemphillian of Tennessee".{{cite journal}}: Cite journal requires |journal= (help)

Bibliography

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