Hyracodontidae
The Hyracodontidae are an extinct family of rhinocerotoids endemic to North America, Europe, and Asia during the Eocene through early Oligocene, living from 48.6 to 26.3 million years ago (Mya), existing about 22.3 million years. Hyracodonts have been nicknamed running rhinoceroses due to their long limbs, which made them more specialized for running than any other rhinocerotoid group.

Heinrich Harder (1858-1935) · Public Domain · via Wikipedia/Commons. May be a photograph of a specimen, or an artist’s reconstruction — an interpretation of a skeleton, since colour and soft tissue are almost never preserved.
On record
Recorded, not inferred- Sits inside
- RhinocerotoideaPBDB
- Diet
- browserPBDB
- Life habit
- ground dwellingPBDB
- Motility
- actively mobilePBDB, for Osteichthyes
- Environment
- terrestrialPBDB, for Eutheria
Time the record covers
At least 20 million years on record.
The record covers at least 48.07 Mya to 27.3 Mya. No occurrence read is dated outside 56 Mya to 18.5 Mya.
238 occurrences of Hyracodontidae on record, most of them in the Eocene. Bar height is expected occurrences, not a count: each fossil is spread across the span it is dated to, so a tall narrow bar means tight dating and a low wide one means loose.
When
238 occurrencesThese are dates about fossils, not the animal: the record can only begin after it arose and end before it died out, so either end may reach further. Shares are expected occurrences: a fossil dated to a span is counted partly in each period it straddles. More on what this infers.
Found in
54 formations
- Brule Formation · White River Group35
- Uinta Formation22
- Chadron Formation · White River Group12
- Ergilin Dzo Formation12
- White River Formation11
- Chambers Tuff Formation6
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The named rock units Hyracodontidae has been recovered from, largest first. Drawn where the rock is now, not where it formed. 30 further formations hold fewer occurrences each and are not listed. 42 occurrences have no formation on record, which is common for older literature.
Hyracodontidae and its relatives
EoceneWhere Hyracodontidae and its relatives were recorded in the Eocene.
Found in the same rock
1,320 taxa- Hyracodon46 sites
- Brontotheriidae41 sites
- Hyracodon nebraskensis27 sites
- Leptomeryx evansi27 sites
- Hesperocyon gregarius26 sites
- Mesohippus bairdi23 sites
- Hyaenodon22 sites
- Ischyromys typus21 sites
- Daphoenus20 sites
- Hesperocyon20 sites
- Merycoidodon culbertsonii20 sites
- Archaeotherium mortoni18 sites
- Palaeolagus haydeni18 sites
- Palaeolagus temnodon18 sites
- Paradjidaumo trilophus18 sites
- Dinictis17 sites
- Herpetotherium fugax17 sites
- Ischyromys veterior17 sites
- Leptomeryx17 sites
- Poebrotherium17 sites
- Protoreodon pumilus16 sites
- Adjidaumo minimus15 sites
- Domnina gradata15 sites
- Leptictidae15 sites
The Paleobiology Database records 200 sites for Hyracodontidae, and this reads all of them. The number is how many of those sites it was catalogued from too. The 24 sharing the most are listed.
This is not a list of everything alive at the time. It is only what has come out of the same ground as this animal and been written down.
Entered from
106 references- Synonymies and reidentifications of North American fossil mammals17
- Hyracodontidae12
- Magnetic stratigraphy and biostratigraphy of the middle Eocene Uinta Formation, Uinta Basin, Utah10
- Hyracodontids and rhinocerotids (Mammalia, Perissodactyla, Rhinocerotoidea) from the Paleogene of Mongolia9
- The Eocene Vertebrates of the Uinta Basin, Utah9
- Early Tertiary Vertebrate Faunas, Trans-Pecos Texas: Ceratomorpha less Amynodontidae7
- Magnetostratigraphy and biostratigraphy of the Eocene-Oligocene transition, southwestern Montana6
- Stratigraphy, Structure, and Vertebrate Fossils of the Oligocene Brule Formation, Slim Buttes, Northwestern South Dakota6
- Fossil mammals of the Lower Miocene White River beds. Collection of 18926
- Mammalian Range Zones in the Chadronian White River Formation at Flagstaff Rim, Wyoming5
- Preliminary biostratigraphy of the White River Group (Oligocene, Chadron and Brule formations) in the vicinity of Chadron, Nebraska5
- Correlation of the early Oligocene (Chadronian) in northwestern Nebraska5
Each of the 238 occurrences read was entered from one of these publications, ordered by how many each accounts for. This is not a search for papers mentioning the name. 94 further references are not listed. Entries link to doi.org where the Paleobiology Database holds an identifier, and to its own record where it does not. Relayed as the Paleobiology Database holds them, not checked against what they resolve to.
Media and terms
Media content1
Picture of Hyracodontidae
- Source
- Wikipedia/Commons
- Credit
- Heinrich Harder (1858-1935)
- Licence
- Public Domain
- Commercial use
- the licence allows it
No 3D scan of Hyracodontidae was found in MorphoSource and Sketchfab.
Smithsonian Open Access was not reached for this taxon, so this list is what the others held rather than everything there is.
The description on this site
- Licence
- CC BY-SA 4.0
This is what the site found, which is not the same as what exists.
Keep going
What may have been alongside itRhinocerotoidea through timeFormations of the EoceneThe world it lived on
Occurrence data from the Paleobiology Database, CC BY 4.0. Cope 1879