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Mammalia - Ungulata - Merycoidodontidae

Synonymy list
YearName and author
1956Miniochoerinae Schultz and Falkenbach p. 391
1996Miniochoerinae Stevens and Stevens p. 538
2007Miniochoerinae Stevens and Stevens p. 160

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phylumChordataHaeckel 1847
subclassDipnotetrapodomorpha(Nelson 2006)
orderUngulata(Linnaeus 1766)

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.

C. B. Schultz and C. H. Falkenbach 1956SKULLSOF SMALLto medium size, dolichoce- phalic to mesocephalic; supraoccipital wings widely spread and incorporated into a fan- shaped occipital region, wings extended pos- teriorly for only a short distance to area above occipital condyles ( supraoccipital wings with greater spread and decidedly less posterior pro- jection than in examples of M erycoidodon, see discussion, p. 388) ; temporal ridge extends forward and outward to anterior border of postorbital process or to a point somewhat an- terior (in Merychyus the ridge extends to the posterior border of postorbital process) ; supra- orbital foramen usually with well-defined an- terior groove, often extending forward and downward on side of face; anterior nasal- maxilla contact in area above C/ ; orbit small and roundish; nasals with slight anterior re- traction ; bulla small (minute in comparison with examples of M erychyus), becoming slightly larger with posterior migration of hyoid pit in each successive species (upper Chadron through Brule) of respective generic and sub- generic lines ; paroccipital process moderately light with antero-extemal area excavated, great- est diameter at approximately 45-degree angle to longitudinal axis of skull, base incorporated into fan-shaped occipital region; postglenoid process compressed anteroposteriorly, external border sloping inward and downward; glenoid surface usually arched anteroposteriorly ; as- cending ramus moderately high ; prominent apophysis or process posterior to mandibular condyle; teeth brachyodont; C/ and P1 large (no indication of large and small C/ and P1 in same species as in Merychyits) ; premolars from small to comparatively large ; P1-P' each with anterior intermediate crest (in many in- stances the C/ has a definite ridge that appears to represent the anterior intermediate crest) ;
posterior portion of M8 decidedly smaller than anterior portion; P' with pillar-like primary cusp on internal side ; superior and inferior molars with shallow fossettes ( see discussion, p. 388) ; Ms with moderately prominent heel.
M. S. Stevens and J. B. Stevens 1996Medium-small to small , mesocephalic (Table 7) oreodonts that have skulls with steep premaxillae, convex nasal profiles, Subnasal L. averages 50-63% of the Nasal L., relatively small orbits located rather low on the sides of the face, persistently small auditory bullae with deep hyoidal grooves, unspecialized zygoma, generally with only a moder- ately prominent, little protracted, and somewhat broadened nuchal crest, and teeth that have thinned and progressively thinner enamel on the middle surfaces of the crests and selenes, a distinctive feature first noted by Leidy (1852, p. 551). Mean pl_P4 values range from 47% to 44% of P1-M 3 (Table 3), mean APM3rrM3 ratios range from 0.98 to 1.05 (Table 5), the M3 is brachydont and mean APM3/Ht. M3 ratios range from 1.85 to 2.07 (Table 4), and the TM3/Ht. M3 ratios increase slightly but regularly (except ?M.
forsythae, 1.89) with time from 1.82 to 1.95 (youngest) as the M3 becomes lower crowned relative to the width (Table 6). Primitive Miniochoerinae have less reduced enamel, longer and narrower occiputs, and deeper preorbital fossae than younger species. Of pertinent subfamilies, Miniochoerinae differ from Oreonetinae Schultz and Falkenbach ( 1956) and Merycoidodontinae Hay (1902) by notably thinned enamel on the premolar- molar crests and selenes; differ from Oreonetinae and early Leptaucheniinae Schultz and Falkenbach (1940, 1968) (Limnenetes) by much larger size; differ from Limnenetes by lower crowned teeth; and differ from post-early Orellan Merycoidodontinae and Leptau- cheniinae by retaining small auditory bullae.
No measurements are available
Composition: phosphaticsubp
Environment: terrestrialo
Locomotion: actively mobilec
Life habit: ground dwellingf
Diet: herbivoref
Created: 2005-08-31 14:37:21
Modified: 2005-08-31 16:37:21
Source: f = family, o = order, c = class, subp = subphylum
References: Carroll 1988, Hendy et al. 2009, Nowak 1999, Lander 1998

Age range: base of the Chadronian to the top of the Whitneyan or 37.20000 to 30.80000 Ma

Collections (95 total)

Time interval Ma Country or state Original ID and collection number
Chadronian37.2 - 33.9USA (Nebraska) Miniochoerus gracilis, Otionohyus wardi (16918) Stenopsochoerus douglasensis (17040)
Chadronian37.2 - 33.9USA (Wyoming) Merycoidodon forsythae (16952 16962 16963 16964 16965) Merycoidodon gracilis (16920) Miniochoerus chadronensis, Otionohyus wardi (16942) Miniochoerus chadronensis, Parastenopsochoerus conversensis, Stenopsochoerus douglasensis (16943) Miniochoerus forsythae (16980) Otionohyus wardi (16974) Stenopsochoerus chadronensis (17024)
Chadronian37.2 - 33.9USA (Colorado) Merycoidodon gracilis (16977)
Chadronian37.2 - 33.9USA (South Dakota) Miniochoerus forsythae (16885) Otionohyus wardi (16967)
Chadronian - Orellan37.2 - 33.3USA (Wyoming) Merycoidodon affinis, Merycoidodon gracilis (17120)
Orellan33.9 - 33.3USA (South Dakota) Merycoidodon gracilis (17102) Miniochoerus affinis (17130 17153) Miniochoerus affinis, Miniochoerus gracilis (17094 17180) Miniochoerus affinis, Oreodon gracilis (17133) Miniochoerus battlecreekensis (17143) Miniochoerus battlecreekensis, Miniochoerus affinis (17065) Miniochoerus gracilis (17162 17173 17174) Miniochoerus gracilis, Platyochoerus platycephalus (17092) Miniochoerus helprini (17179 17192) Platyochoerus heartensis (17296) Platyochoerus platycephalus (17115) Stenopsochoerus berardae (17188)
Orellan33.9 - 33.3USA (Wyoming) Miniochoerus affinis (17118 17149) Miniochoerus chadronensis (17104 17105) Miniochoerus gracilis (17106) Miniochoerus gracilis, Platyochoerus platycephalus (17178) Platyochoerus platycephalus (17193 17196) Stenopsochoerus sternbergi, Miniochoerus battlecreekensis (17152)
Orellan33.9 - 33.3USA (North Dakota) Miniochoerus starkensis (17129)
Orellan33.9 - 33.3USA (Montana) Miniochoerus sp. (17090)
Orellan33.9 - 33.3USA (Nebraska) Miniochoerus affinis (17199 17243 17254 17262 17272 17282) Miniochoerus affinis, Miniochoerus gracilis (17201 17206 17209 17213 17219 17246 17251 17271 17285) Miniochoerus battlecreekensis (17224 17228 17263) Miniochoerus gracilis (17047 17062 17122 17135 17165 17230 17234 17238 17289 17290) Miniochoerus gracilis, Miniochoerus battlecreekensis (17281) Miniochoerus gracilis, Platyochoerus platycephalus (17098) Miniochoerus helprini (17222) Miniochoerus starkensis (17299) Platyochoerus heartensis (17164 17288) Platyochoerus platycephalus (17259 17267 17278) Stenopsochoerus sternbergi (17175 17300)
Whitneyan33.3 - 30.8USA (South Dakota) Miniochoerus cheyennensis (17338 17343 17380) Platyochoerus hatcreekensis (17336)
Whitneyan33.3 - 30.8USA (Nebraska) Miniochoerus nicholsae (17418) Miniochoerus ottensi (17409 17410 17414 17434) Stenopsochoerus berardae (17420) Stenopsochoerus joderensis, Miniochoerus helprini (17435)