// Workers AI · dad joke modeWhat did Bathygenys say? "I'm deep in thought".

Bathygenys; Temporal range: 37–34 Ma PreꞒ Ꞓ O S D C P T J K Pg N Pal. Eocene Oligo. Miocene P P (Chadronian, late Eocene)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Infraclass:	Placentalia
Order:	Artiodactyla
Family:	†Merycoidodontidae
Genus:	†Bathygenys; Douglass, 1901
Type species
	†Bathygenys alpha;
Species
	B. alpha Douglass, 1901; B. hedlundae Schultz & Falkenbach, 1968; B. reevesi Wilson, 1971;
Synonyms
	Genus synonymy Megabathygenys Schultz & Falkenbach, 1968 ; Parabathygenys Schultz & Falkenbach, 1968 ; Species synonymy M. goorisi Schultz & Falkenbach, 1968 ; P. paralpha Schultz & Falkenbach, 1968 ;

Bathygenys is an extinct genus of oreodont within the family Merycoidodontidae and subfamily Oreonetinae, endemic to western North America. It lived during the late Eocene (Chadronian NALMA).^[1]^[2]^[3]

Like other oreodonts, Bathygenys was a herbivore which probably had a heavily-built body, short tail, short feet, and four-toed hooves.^{[citation needed]} It was one of the earliest and smallest known oreodonts, with a relatively deep lower jaw and a small, rounded periotic bone.^[2] Bathygenys is used as the main mammalian index fossil of the Chadronian age.^[3]

Species

B. alpha

The type species, B. alpha, was originally named based on lower jaw fragments from Pipestone Springs, a site in the Renova Formation of Montana dated to the middle Chadronian (about 35 Ma). The species was named by Carnegie Museum paleontologist Earl Douglass in 1901, who described these original fragments. William Diller Matthew (1903), from the American Museum of Natural History, also collected some skull material from the site, though the AMNH fossils have subsequently been lost.^[2]

More extensive fossils of B. alpha are known from the White River Formation of Wyoming, particularly the Flagstaff Rim and Ledge Creek areas of Natrona County and the Yoder local fauna of Goshen County. "Megabathygenys goorisi" from Ledge Creek is probably a junior synonym of B. alpha.^[2]

Bathygenys fossils have also been reported from the Calf Creek local fauna (Cypress Hills Formation) in Saskatchewan and the Kings Canyon site (White River Formation) in Colorado.^[4]^[1]

B. hedlundae

B. hedlundae is the smallest Bathygenys species, and is only found in middle Chadronian beds at Flagstaff Rim in Wyoming. Originally considered a subspecies of B. alpha, it can be distinguished by a deeper preorbital fossa. Parabathygenys paralpha is a junior synonym of this species.^[2]

B. reevesi

B. reevesi is the largest Bathygenys species, and the most abundant, with numerous fossils from the Little Egypt local fauna in Presidio County, Texas.^[5] This also makes it the oldest Bathygenys species, since the Little Egypt local fauna is earliest Chadronian in age (~37 Ma). Bathygenys fossils from other Chadronian local faunas in the area (Airstrip and Ash Springs in Texas, Rancho Gaitan in Chihuahua) also appear to be B. reevesi.^[2]

Resources

1 2 Lloyd, K. J.; Eberle, J. J. (2012-09-01). "A late Eocene (Chadronian) mammalian fauna from the White River Formation in Kings Canyon, northern Colorado". Rocky Mountain Geology. 47 (2): 113–132. doi:10.2113/gsrocky.47.2.113. ISSN 1555-7332.
1 2 3 4 5 6 Watmore, Kristin I.; Stevens, Margaret Skeels; Prothero, Donald R.; Marriott, Katherine (2024). "Systematics of the late Eocene 'oreonetine' oreodonts (Merycoidodontidae: Artiodactyla)". Historical Biology. 36 (9): 1834–1853. doi:10.1080/08912963.2023.2234390. ISSN 0891-2963.
1 2 Prothero, Donald R.; Emry, Robert J. (2004). "5. The Chadronian, Orellan, and Whitneyan North American Land Mammal Ages". In Woodburne, Michael O. (ed.). Late Cretaceous and Cenozoic Mammals of North America: Biostratigraphy and Geochronology. Columbia University Press. pp. 156–168. doi:10.7312/wood13040-007. ISBN 978-0-231-13040-0. JSTOR 10.7312/wood13040.11.
↑ Storer, John E. (1996-06-13), "Eocene-Oligocene faunas of the Cypress Hills Formation, Saskatchewan", in Prothero, Donald R.; Emry, Robert J. (eds.), The Terrestrial Eocene-Oligocene Transition in North America (1 ed.), Cambridge University Press, pp. 240–261, doi:10.1017/cbo9780511665431.013, ISBN 978-0-521-43387-7, retrieved 2026-07-31
↑ Wilson, John A. (1971). "Early Tertiary Vertebrate Faunas, Vieja Group, Trans-Pecos Texas, Agriochoeridae and Merycoidodontidae". Bulletin of the Texas Memorial Museum, University of Texas at Austin. 18: 1–83.

[:12-1] 1 2 Lloyd, K. J.; Eberle, J. J. (2012-09-01). "A late Eocene (Chadronian) mammalian fauna from the White River Formation in Kings Canyon, northern Colorado". Rocky Mountain Geology. 47 (2): 113–132. doi:10.2113/gsrocky.47.2.113. ISSN 1555-7332.

[:0-2] 1 2 3 4 5 6 Watmore, Kristin I.; Stevens, Margaret Skeels; Prothero, Donald R.; Marriott, Katherine (2024). "Systematics of the late Eocene 'oreonetine' oreodonts (Merycoidodontidae: Artiodactyla)". Historical Biology. 36 (9): 1834–1853. doi:10.1080/08912963.2023.2234390. ISSN 0891-2963.

[:02-3] 1 2 Prothero, Donald R.; Emry, Robert J. (2004). "5. The Chadronian, Orellan, and Whitneyan North American Land Mammal Ages". In Woodburne, Michael O. (ed.). Late Cretaceous and Cenozoic Mammals of North America: Biostratigraphy and Geochronology. Columbia University Press. pp. 156–168. doi:10.7312/wood13040-007. ISBN 978-0-231-13040-0. JSTOR 10.7312/wood13040.11.

[4] Storer, John E. (1996-06-13), "Eocene-Oligocene faunas of the Cypress Hills Formation, Saskatchewan", in Prothero, Donald R.; Emry, Robert J. (eds.), The Terrestrial Eocene-Oligocene Transition in North America (1 ed.), Cambridge University Press, pp. 240–261, doi:10.1017/cbo9780511665431.013, ISBN 978-0-521-43387-7, retrieved 2026-07-31

[5] Wilson, John A. (1971). "Early Tertiary Vertebrate Faunas, Vieja Group, Trans-Pecos Texas, Agriochoeridae and Merycoidodontidae". Bulletin of the Texas Memorial Museum, University of Texas at Austin. 18: 1–83.

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