Achelousaurus horneri
Achelousaurus is a genus of centrosaurine ceratopsid dinosaur that lived during the Late Cretaceous Period of what is now North America, about 77 to 74.8 million years ago. The first fossils of Achelousaurus were collected in Montana in 1987, by a team led by Jack Horner, with more finds made in 1989. In 1994, Achelousaurus horneri was described and named by Scott D. Sampson; the generic name means "Achelous lizard", in reference to the Greek deity Achelous, and the specific name refers to Horner. The genus is known from a few specimens consisting mainly of skull material from individuals, ranging from juveniles to adults.

Tim Evanson from Washington, D.C., United States of America · CC BY-SA 2.0 · 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
- AchelousaurusPBDB
- Diet
- herbivorePBDB, for Ceratopsia
- Life habit
- ground dwellingPBDB, for Ceratopsia
- Motility
- actively mobilePBDB, for Ornithischia
- Environment
- terrestrialPBDB, for Ceratopsia
Time the record covers
At most 12 million years on record.
Every occurrence read is dated to somewhere between 83.6 Mya and 72.2 Mya, and nothing in the dating separates them, so that window is what the record shows rather than a span.
2 occurrences of Achelousaurus horneri on record, most of them in the Late Cretaceous. 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
2 occurrences- Late Cretaceous100%
These 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
1 formation
- Two Medicine Formation · Montana Group2
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The named rock units Achelousaurus horneri has been recovered from, largest first. Drawn where the rock is now, not where it formed.
Achelousaurus horneri and its relatives
Late CretaceousWhere Achelousaurus horneri and its relatives were recorded in the Late Cretaceous.
Found in the same rock
7 taxa- Ankylosauria1 site
- Ankylosauridae1 site
- Brontotholus harmoni1 site
- Daspletosaurus horneri1 site
- Hadrosauridae1 site
- Prosaurolophus maximus1 site
- Saurischia1 site
The Paleobiology Database records 2 sites for Achelousaurus horneri, and this reads all of them. The number is how many of those sites it was catalogued from too.
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
2 references- Two new horned dinosaurs from the upper Cretaceous Two Medicine Formation of Montana; with a phylogenetic analysis of the Centrosaurinae (Ornithischia: Ceratopsidae)1
- Two new horned dinosaurs (Ornithischia: Ceratopsidae) from the Upper Cretaceous Two Medicine Formation, Montana, USA1
Each of the 2 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. 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 Achelousaurus horneri
- Source
- Wikipedia/Commons
- Credit
- Tim Evanson from Washington, D.C., United States of America
- Licence
- CC BY-SA 2.0
- Commercial use
- the licence allows it
No 3D scan of Achelousaurus horneri was found in Sketchfab.
Smithsonian Open Access and MorphoSource were 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 itAchelousaurus through timeFormations of the Late CretaceousThe world it lived on
Occurrence data from the Paleobiology Database, CC BY 4.0. Sampson 1994