View source for Megacerops

{{Short description|Extinct Perissodactyl ungulate genus from Late Eocene epoch}}
{{Expand German|topic=scitech|date= June 2022}}
{{Automatic taxobox
| fossil_range = [[Late Eocene]] ([[Priabonian]]), {{fossil range|38|33.9}}
| image = Brontops in Los Angeles.jpg
| image_caption = Mounted skeleton, [[Natural History Museum of Los Angeles County]]
| taxon = Megacerops
| authority = [[Joseph Leidy|Leidy]], 1870
| display_parents = 4
| subdivision_ranks = Species
| subdivision =
*†''M. coloradensis'' <small>Leidy, 1870 ([[type species]])</small>
*†''M. kuwagatarhinus'' <small>Mader and Alexander, 1995</small>
| synonyms =
*''Brontotherium'' <small>Cope, 1873</small>
*''Brontops''
*''Menodus''
*''Titanotherium''
*''Ateleodon''
*''Oreinotherium'' 
}}

'''''Megacerops''''' ("large-horned face", from ''[[wikt:μεγα|méga-]]'' "large" + ''[[wikt:κέρας|kéras]]'' "horn" + ''[[wikt:ὤψ|ōps]]'' "face") is an [[extinct]] [[genus]] of the prehistoric [[odd-toed ungulate]] (hoofed mammal) [[family (biology)|family]] [[Brontotheriidae]], an extinct group of [[rhinoceros]]-like browsers related to [[horse]]s. It was endemic to [[North America]] during the [[Late Eocene]] epoch (38–33.9 [[Year|mya]]), existing for approximately {{Mya|38-33.9|million years}}.<ref>{{Cite web |title=PBDB Taxon |url=https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=43043 |access-date=2025-04-14 |website=paleobiodb.org}}</ref>

==Taxonomy==
''Megacerops'' was named by Leidy (1870). Its type species is ''Megacerops coloradensis''. It was synonymized subjectively with ''Menodus'' by Clark and Beerbower (1967). It was assigned to Brontotheriidae by Leidy (1870), Carroll (1988), Mader (1989), and Mader (1998).<ref>J. Clark and J. R. Beerbower. 1967. Geology, paleoecology, and paleoclimatology of the Chadron Formation. Fieldiana</ref><ref>{{cite book |last1=Carroll |first1=Robert L. |title=Vertebrate Paleontology and Evolution |date=1988 |publisher=Freeman |isbn=978-0-7167-1822-2 }}{{page needed|date=April 2022}}</ref>

According to Mihlbachler and others,<ref>{{cite journal|author=Mihlbachler, M.C., Lucas, S.G., and Emry, R.J.|year=2004|title=The holotype specimen of ''Menodus giganteus'', and the "insoluble" problem of ''Chadronian brontothere'' taxonomy|journal=New Mexico Museum of Natural History and Science Bulletin|volume=26|pages= 129–136 |url=https://books.google.com/books?id=fJivCQAAQBAJ&pg=PA129 }}</ref><ref>{{cite thesis |last1=Mihlbachler |first1=Matthew Christian |title=Phylogenetic systematics of the Brontotheriidae (Mammalia, Perissodactyla) |date=2005 |id={{ProQuest|305015315}} |oclc=79487069 }}{{page needed|date=April 2022}}</ref> ''Megacerops'' includes the species of the genera ''Menodus'', ''Brontotherium'', ''Brontops'', ''Menops'', ''Ateleodon'', and ''Oreinotherium''.

==Description==
[[File:Megacerops-coloradensis.jpg|thumb|left|Restoration of ''M. coloradensis'']]
[[File:Megacerops head reconstruction at AMNH.jpg|thumb|left|''Megacerops'' head reconstruction at the [[American Museum of Natural History]]]]
All of the species had a pair of blunt [[Horn (anatomy)|horn]]s on their snout (the size varying between species), with the horns of males being much longer than those of the females. This could indicate that they were social animals which butted heads for breeding privileges.

Despite resembling the rhinoceros, it was larger than any living rhinoceros: the living animal easily approached the size of the [[African forest elephant]], the third-largest land animal today. It stood about {{convert|2.5|m|ftin|abbr=on}} tall at the shoulders with an overall length (including tail) of {{convert|4.63|m|ft|abbr=on}}.<ref name="Osborn 1929">{{cite book |last=Osborn |first=Henry F. |author-link= |date=1929 |title=The titanotheres of ancient Wyoming, Dakota, and Nebraska |url=https://archive.org/details/titanotheresofan01osbo/|location= |publisher=Dept. of the Interior, U.S. Geological Survey |page= |isbn=}}</ref>{{rp|666}} Its skull reached {{cvt|89.5|cm}} in greatest length, with some specimens possessing substantial canines, up to 70&nbsp;mm long.<ref name="Osborn 1929" />{{rp|494,523}} ''Megacerops'' resembled a large rhinoceros, possessing blunt Y-shaped horn-like protrusions on its nose up to 43&nbsp;cm in length.<ref name="Osborn 1929" />{{rp|553}} Its mass is estimated to be in the range of {{convert|3.3-3.8|t|ST|abbr=on}} <ref>{{cite web|last=Gregory S.|first=Paul|title=Mass estimate table|url=http://www.gspauldino.com/data.html|archive-url=https://web.archive.org/web/20141101154902/http://gspauldino.com/data.html|archive-date=1 November 2014|access-date=20 September 2022}}</ref><ref>{{cite journal |last1= Bales|first1=Gerald S. |date= 1996|title=Heterochrony in Brontothere Horn Evolution: Allometric Interpretations and the Effect of Life History Scaling|url=https://www.cambridge.org/core/journals/paleobiology/article/abs/heterochrony-in-brontothere-horn-evolution-allometric-interpretations-and-the-effect-of-life-history-scaling/3E46D81D1562F29022571A657955382A |journal=Paleobiology |volume=22 |issue= 4|pages= 481–495|doi=10.1017/S009483730001647X |bibcode=1996Pbio...22..481B |s2cid=89214971 |access-date=September 26, 2022|url-access=subscription }}</ref>

The dorsal [[vertebra]]e above the shoulders had extra long spines to support the huge neck muscles needed to carry the heavy [[skull]]. The shape of its teeth suggests that it preferred food such as soft stems and leaves, rather than tough vegetation. It may have had fleshy lips and a long tongue for carefully selecting food.

==Paleobiology==
[[File:Megacerops coloradensis skull 1 (cropped).jpg|left|thumb|AMNH 518, from [[South Dakota]]. This ''M. coloradensis'' specimen has a healed broken rib, not pictured here.]]
The skeleton of an adult male was found with partially healed [[rib]] fractures, which supports the theory that males used their 'horns' to fight each other. No creature living in ''Megacerops''{{'}} time and area except another ''Megacerops'' could have inflicted such an injury.<ref name=EoDP>{{cite book |editor=Palmer, D.|year=1999 |title= The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals|publisher= Marshall Editions|location=London|pages= 258–259|isbn= 978-1-84028-152-1}}</ref> The breathing movements prevented the fractures from completely healing. The adults may have also used their horns to defend themselves and their calves from predators, such as [[Hyaenodontidae|hyaenodonts]], [[entelodonts]], ''[[Bathornis]]'' or [[Nimravidae|nimravids]].

==Distribution==
Fossils were uncovered in the northern plains states. Life-sized models of ''Megacerops'' families (a male, female, and juvenile) are displayed at the James E. Martin Paleontological Research Laboratory, South Dakota School of Mines & Technology, and a different set at the [[Canadian Museum of Nature]].

Many remains have been found in [[South Dakota]] and [[Nebraska]]. In the past, specimens exposed by severe [[rain]]storms were found by [[Native Americans in the United States|Native Americans]] of the [[Sioux]] tribes. The Sioux called them "thunder beasts", a name preserved in the ancient Greek translation (bronto-, ''thunder;'' therion, ''beast'').<ref>{{Cite web|url=https://web.stanford.edu/dept/HPS/MayorPlacenames.pdf|title=Placenames Describing Fossils in Oral Traditions|last=Mayor|first=Adrienne|access-date=2019-06-21|archive-date=2014-09-04|archive-url=https://web.archive.org/web/20140904044500/https://web.stanford.edu/dept/HPS/MayorPlacenames.pdf|url-status=dead}}</ref> Many of the [[skeleton]]s found by the Sioux belonged to [[herd]]s which were killed by [[Types of volcanic eruptions|volcanic eruptions]] of the [[Rocky Mountains]], which were volcanically active at the time.

==See also==
* {{Portal-inline|Paleontology}}

==References==
{{Reflist}}

==External links==
{{Commons category|Megacerops}}
{{Wikispecies|Megacerops}}

*[https://www.livescience.com/animals/extinct-species/rhino-like-thunder-beasts-grew-massive-in-the-evolutionary-blink-of-an-eye-after-dinos-died-off Fast evolution of Megacerops after the end-Cretaceous mass extinction], 12 May 2023, [[Live Science]]

{{Perissodactyla Genera|P.}}
{{Brontotheriidae}}
{{Taxonbar|from=Q135590}}

[[Category:Brontotheres]]
[[Category:White River Fauna]]
[[Category:Eocene mammals of North America]]
[[Category:Priabonian genera]]
[[Category:Fossil taxa described in 1870]]
[[Category:Taxa named by Joseph Leidy]]