Organism · Placental mammals
Mesohippus bairdi
Source time context (not species duration) · ≈ 33.9–23 Ma
Inferred life reconstruction
Mesohippus bairdi
Overview
Mesohippus bairdi is an early horse known to have three toes. Skull and foot material can be compared with the body structure described at genus level. It reveals a different arrangement from the single hoof of living horses.[1][2]
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Key facts
Museum accounts of the genus Mesohippus describe three toes on both the forefeet and hind feet. Dental comparisons also show premolars becoming more like molars. Feet and teeth reveal different kinds of change.[2][4]
Time and place
It is introduced through early Oligocene material from the present-day USA. Archives also record an Oligocene skull and hind foot from Wyoming. The Oligocene spans roughly 34–23 million years ago.[1][3][5]
The time range describes source context, not the complete duration of this species.
Size, form and skeleton
Genus-level sources describe an elongated snout, a depression in the face, and three toes on both forefeet and hind feet. Species-specific archives record a skull and a right hind foot. Broad body organization can be compared with the parts known from actual material.[2][3]
A replica skeleton of this species presented by the North Dakota Geological Survey has a shoulder height of 46.5 cm. This value describes the size of one displayed skeleton.[6]
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Habitat and reproduction
How did the teeth of early horses change? Sources on Mesohippus describe premolars becoming more similar to molars. Small teeth within the jaw, as well as toes, provide clues to life habits and evolution.[4]
Fossil discovery
The George Sternberg archive records a skull of Mesohippus bairdi and the right hind foot of a three-toed horse. Museums introduce the feet, heads, and teeth of early horses. Species-level specimen records and genus-level comparisons contribute different information.[3][2][4]
References
- Fukui Prefectural Dinosaur Museum — Mesohippus bairdi
- Humboldt State University Natural History Museum — Early horses
- George Sternberg archive — Mesohippus skull and hind foot
- Florida Museum of Natural History — Mesohippus fossil horse material
- International Commission on Stratigraphy (2024) — Geological time chart
- North Dakota Geological Survey — Skeleton of Mesohippus bairdi
- Bernor et al. (1997) — Hippotherium from Höwenegg
Research questions
Do toes and teeth reveal the same changes? One provides clues to the arrangement at the ends of limbs, while the other reveals forms used to process food. Mesohippus allows early horses to be explored through several body regions.[2][4]
Observation
Picture the elongated snout, teeth, and three-toed arrangement in turn. Comparing the feet with those of living horses helps bring differences in the head and limbs into view together.[2][4]
Related organisms
Hippotherium primigeniumPlacental mammalsSource time context (not species duration) · ≈ 23–5.33 MaDifferent bodies among horses
Explore the bodies and backgrounds of Mesohippus bairdi and Hippotherium primigenium together. Mesohippus bairdi: an early horse known to have three toes, with skull and foot material that can be compared with genus-level body structure. Hippotherium primigenium: a three-toed member of the horse family whose late Miocene material from Höwenegg has been studied in detail.