Menoceras

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Menoceras
Temporal range: early Miocene, [1] 23.1–12.5  Ma
Menoceras arikarense skeleton.jpg
Mounted M. arikarense skeleton
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Perissodactyla
Family: Rhinocerotidae
Subfamily:† Elasmotheriinae
Genus:† Menoceras
(Troxell, 1921)
Type species
Menoceras arikarense
Species [2]
  • M. arikarense
  • M. barbouri
Synonyms
  • MoschoedestesStevens, 1969 [3]
  • Diceratherium cooki
  • Diceratherium arikarense

Menoceras ("Crescent Horns" [4] ) is a genus of extinct, small rhinocerotids endemic to most of southern North America and ranged as far south as Panama during the early Miocene epoch. It lived from around 23.1-12.5 Ma, existing for approximately 10.6 million years. [5]

Contents

Description

Menoceras was much smaller than any living rhinoceros, with the genus being compared in size to a sheep [6] or a pig, [7] an with estimated bodymass of 313 kilograms (690 lb). [8] Male Menoceras sported two horns side by side at the tip of the nose, whereas the females were hornless or had greatly reduced horns, and have differently shaped nasal bones. [6] Menoceras along with Diceratherium is unique in having paired horns among rhinocerotids. [7] Both sexes of Menoceros grew to a length of 5 feet (1.5 meters) long.[ citation needed ]

Paleobiology

1913 illustration of M. arikarense. Diceratherium cooki.jpg
1913 illustration of M. arikarense.

Menoceras roamed across a tropical, savanna-like grassland and plains environment that covered much of North America. [9] Because of the massive accumulations of fossil bones of this animal, particularly at Agate Springs Nebraska, Menoceras may have lived in large herds. Other sites include Martin-Anthony site Martin County, Florida, and Cady Mountains Horse Quarry, San Bernardino County, California. [10]

Taxonomy

Female (top) and male (bottom) M. arikarense skulls Menoceras arikarense female and male skulls (cropped).jpg
Female (top) and male (bottom) M. arikarense skulls

Menoceras was named by Troxell and assigned to Rhinocerotidae in 1921. It was synonymized subjectively with Diceratherium by Matthew in 1931 and Wood in 1964. Again assigned to Rhinocerotidae by Prothero, Guerrin, Manning in 1989. [11] Tanner (1969), Wilson and Schiebout (1981), Prothero and Manning (1987), Carroll (1988) and Prothero et al. (1989); and to Menoceratinae by Prothero (1998). [12]

Fossil distribution

Life reconstruction of M. barbouri Menoceras NT small.jpg
Life reconstruction of M. barbouri

Fossil distribution is as far north as New Jersey, south to Florida (3 collections) and Texas (6 collections), as far west as Nebraska (7 collections) and California (2 collections).

The Panamanian find was determined to be 19.7 Ma (AEO). It was found in the Gaillard Cut in Panama in "a 45 m thick section (narrow stratigraphic interval)" [13] It was reposited in the Smithsonian Institution, Washington, D.C. Other sites:

Notes

  1. ↑ Prothero, 2005, p. 189.
  2. ↑ Prothero, 2005, p. 59.
  3. ↑ Prothero, 2005, pp. 65-67.
  4. ↑ "Glossary. American Museum of Natural History". Archived from the original on 20 November 2021.
  5. ↑ "Menoceras". fossilworks. Retrieved 6 May 2025.
  6. 1 2 Mihlbachler, Matthew C. (2007-11-15). "Sexual Dimorphism and Mortality Bias in a Small Miocene North American Rhino, Menoceras arikarense: Insights into the Coevolution of Sexual Dimorphism and Sociality in Rhinos" . Journal of Mammalian Evolution. 14 (4): 217–238. doi:10.1007/s10914-007-9048-4. ISSN   1064-7554.
  7. 1 2 D.R. Prothero "Rhinocerotidae" C.M. Janis, K.M. Scott, L. Jacobs (Eds.), Evolution of Tertiary Mammals of North America, Cambridge University Press, Cambridge (1998), pp. 595-605
  8. ↑ Mallet, Christophe; Houssaye, Alexandra; Cornette, Raphaël; Billet, Guillaume (2022-11-02). "Long bone shape variation in the forelimb of Rhinocerotoidea: relation with size, body mass and body proportions". Zoological Journal of the Linnean Society. 196 (3): 1201–1234. doi:10.1093/zoolinnean/zlab095. ISSN   0024-4082.
  9. ↑ Prothero, 2005
  10. ↑ PaleoDB collection 19233, authorized by Dr. John Alroy, May 15, 2002.
  11. ↑ D. R. Prothero, C. Guerin, and E. Manning. 1989. The history of the Rhinocerotoidea. In D. R. Prothero and R. M. Schoch (eds.), The Evolution of Perissodactyls 321-340.
  12. ↑ D. R. Prothero. 1998. Rhinocerotidae. In C. M. Janis, K. M. Scott, and L. L. Jacobs (eds.), Evolution of Tertiary mammals of North America 595-605.
  13. ↑ Cucaracha Formation, Gaillard Cut, Panama. J. Alroy. 2002. Synonymies and reidentifications of North American fossil mammals.

References

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