PBDB Taxon

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Eporeodon occidentalis

Mammalia - Merycoidodontidae

Taxonomy

Oreodon occidentalis was named by Marsh (1873). Its type specimen is YPM 10142, a partial skull, and it is a 3D body fossil. It is the type species of Eporeodon.

It was recombined as Eucrotaphus occidentalis by Cope (1879); it was synonymized subjectively with Eucrotaphus jacksoni by Cope (1884); it was recombined as Merycochoerus occidentalis by Fremd (1994); it was recombined as Eporeodon occidentalis by Marsh (1875), Marsh (1884), Hay (1902), Douglass (1906), Thorpe (1921), Thorpe (1924), Thorpe (1937), Schultz and Falkenbach (1968), Lander (1998), Stevens and Stevens (2007), Stevens et al. (2023).

Subspecies

Eporeodon trigonocephalus parvus

Synonyms

Dayohyus wortmani was named by Schultz and Falkenbach (1968) [genotype]. Its type specimen is UCMP 1911, a partial skull (Skull with I1(rt.)-M3 (P1-P2 rt.).), and it is a 3D body fossil. It is the type species of Dayohyus.

It was synonymized subjectively with Eucrotaphus trigonocephalus by Lander (1998); it was synonymized subjectively with Eporeodon occidentalis by Stevens et al. (2023).
Eporeodon condoni was named by Thorpe (1921). Its type specimen is YPM 11016 and is a 3D body fossil.

It was recombined as Pseudogenetochoerus condoni by Schultz and Falkenbach (1968); it was synonymized subjectively with Eucrotaphus trigonocephalus by Lander (1998); it was synonymized subjectively with Eporeodon occidentalis by Stevens et al. (2023).
Eporeodon davisi was named by Schultz and Falkenbach (1968). Its type specimen is AM 7576, a partial skull (Partial skull with P2(rt.)-M3), and it is a 3D body fossil. Its type locality is The Cove, which is in a Miocene/Miocene terrestrial horizon in the John Day Formation of Oregon.

It was synonymized subjectively with Eporeodon occidentalis by Lander (1998), Stevens et al. (2023).
Eporeodon thurstoni was named by Stock (1934). Its type specimen is CIT 1566, a skeleton (partial skull and most of skeleton), and it is a 3D body fossil. Its type locality is Willard Canyon, South Mountain (CIT 157), which is in an Arikareean fluvial-lacustrine siltstone/sandstone in the Sespe Formation of California.

It was recombined as Desmatochoerus (Paradesmatochoerus) thurstoni by Schultz and Falkenbach (1954); it was synonymized subjectively with Merycoides pariogonus by Lander (1983); it was recombined as Desmatochoerus thurstoni by Mason and Swisher (1989); it was synonymized subjectively with Merycoides relictus by Lander (1998); it was synonymized subjectively with Eporeodon occidentalis by Stevens et al. (2023).
Eucrotaphus trigonocephalus was named by Cope (1884). Its type specimen is AMNH 7505, a partial skull (Skull with I1-P1 rt. and P2-M3 (alv.) (P3 and M1 alv.)), and it is a 3D body fossil.

It was recombined as Eporeodon trigonocephalus by Roger (1896), Hay (1902), Thorpe (1921), Thorpe (1937), Stevens and Stevens (2007); it was recombined as Dayohyus trigonocephalus by Schultz and Falkenbach (1968); it was synonymized subjectively with Eporeodon occidentalis by Stevens et al. (2023).

Synonymy list

Year	Name and author
1873	Oreodon occidentalis Marsh p. 409
1875	Eporeodon occidentalis Marsh p. 250
1879	Eucrotaphus occidentalis Cope
1884	Eucrotaphus trigonocephalus Cope p. 514
1884	Eporeodon occidentalis Marsh
1896	Eporeodon trigonocephalus Roger
1902	Eporeodon occidentalis Hay p. 667
1902	Eporeodon trigonocephalus Hay p. 667
1906	Eporeodon occidentalis Douglass p. 566
1921	Eporeodon occidentalis Thorpe
1921	Eporeodon trigonocephalus Thorpe p. 101
1921	Eporeodon condoni Thorpe p. 104
1924	Eporeodon occidentalis Thorpe
1934	Eporeodon thurstoni Stock
1937	Eporeodon condoni Thorpe p. 66 figs. Figs. 31-33
1937	Eporeodon occidentalis Thorpe p. 82 figs. Figs. 41-43
1937	Eporeodon thurstoni Thorpe p. 96 figs. PI. XLIII, fig. 1
1937	Eporeodon trigonocephalus Thorpe p. 96 figs. PI. VIII, figs. 4-6
1954	Desmatochoerus (Paradesmatochoerus) thurstoni Schultz and Falkenbach p. 202
1960	Eporeodon thurstoni Stirton p. 363
1968	Dayohyus trigonocephalus Schultz and Falkenbach
1968	Dayohyus wortmani Schultz and Falkenbach
1968	Eporeodon davisi Schultz and Falkenbach
1968	Pseudogenetochoerus condoni Schultz and Falkenbach
1968	Eporeodon occidentalis Schultz and Falkenbach p. 201 figs. Figures 24, 30, 52
1968	Eporeodon davisi Schultz and Falkenbach p. 203 figs. Figures 24, 30, 52
1968	Dayohyus wortmani Schultz and Falkenbach p. 217 figs. Figures 28-30, 52.
1989	Desmatochoerus thurstoni Mason and Swisher
1994	Eucrotaphus trigonocephalus Fremd
1994	Merycochoerus occidentalis Fremd
1998	Eporeodon occidentalis Lander
1998	Eucrotaphus trigonocephalus Lander
2007	Eporeodon occidentalis Stevens and Stevens p. 160
2007	Eporeodon thurstoni Stevens and Stevens p. 160
2007	Eporeodon trigonocephalus Stevens and Stevens p. 164
2023	Eporeodon occidentalis Stevens et al. p. 18 figs. Figures 2, 10-14; Tables A1, A2

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Rank	Name	Author
kingdom	Animalia	()
—	Bilateria
—	Eubilateria	Ax 1987
—	Deuterostomia
phylum	Chordata	Haeckel 1874
subphylum	Vertebrata
superclass	Gnathostomata
—	Osteichthyes	()
subclass	Sarcopterygii	()
subclass	Dipnotetrapodomorpha	(Nelson 2006)
subclass	Tetrapodomorpha	()
—	Tetrapoda
—	Reptiliomorpha
—	Anthracosauria
subclass	Amphibiosauria	Kuhn 1967
—	Cotylosauria	()
—	Amniota
subclass	Synapsida
—	Therapsida	()
infraorder	Cynodontia	()

Rank	Name	Author
—	Mammaliamorpha
—	Mammaliaformes
class	Mammalia
—	Cladotheria
—	Zatheria
subclass	Tribosphenida	()
subclass	Theria
—	Eutheria	()
—	Placentalia
—	Boreoeutheria
—	Laurasiatheria
—	Scrotifera
—	Euungulata
—	Artiodactylamorpha
—	Artiodactyla	()
suborder	Tylopoda	()
family	Merycoidodontidae
subfamily	Eporeodontinae
genus	Eporeodon
species	occidentalis	()

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

†Eporeodon occidentalis Marsh 1873

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†Eporeodon trigonocephalus parvus Thorpe 1921

Invalid names: Dayohyus wortmani Schultz and Falkenbach 1968 [synonym], Eporeodon condoni Thorpe 1921 [synonym], Eporeodon davisi Schultz and Falkenbach 1968 [synonym], Eporeodon leptacanthus Cope 1884 [synonym], Eporeodon thurstoni Stock 1934 [synonym], Eucrotaphus trigonocephalus Cope 1884 [synonym]

Diagnosis

Reference	Diagnosis
M. R. Thorpe 1937 (Eporeodon thurstoni)	This species approaches E. socialis in size but is somewhat smaller. There is an antorbital pit, and the bulla; are large. The orbit is decidedly large. The skull lacks the greater portion of the cranium, so that it is unwise to diagnose the skull characters until more comparable material is brought to light. Skeleton: Stock records the fact that the right pes has a rudimentary element articulated with the navicular and situated above the proximal end of Mt. II. He infers that it may represent a fused entocuneiform and rudimentary Mt. I. Its posterodistal end is rounded.
C. B. Schultz and C. H. Falkenbach 1954 (Desmatochoerus (Paradesmatochoerus) thurstoni)	SKULL: Smaller than skulls of D. (P.) sanfordi and Merycoides cursor; prelacrimal fossa present; bulla large. MANDIBLE: (See discussion below). DENTITION: Superior series estimated to be shorter than examples of D. (P.) sanfordi, slightly longer than those of M. cursor. LIMBS:Resembling examples of Subdesmatochoerus socialis.
M. S. Stevens et al. 2023	Smallest species of Eporeodon (M1-3 length =35-45 mm), with a relatively small auditory bulla, and a less fan-shaped occipital crest.