Stratum.black
Allosaurus — Allosaurus
Allosaurus — Artwork by Scott Hartman, published by Daniel J. Chure, Mark A. Loewen, Wikimedia Commons, CC BY 4.0

Dinosaur

Allosaurus

Different lizard

Allosaurus is the dominant Late Jurassic predator of the Morrison Formation and the most common theropod in trade from that unit. Its teeth are laterally compressed and recurved with fine serrations on both edges; complete rooted teeth, claws and vertebrae come from private Wyoming and Colorado quarries. Cleveland-Lloyd Quarry in Utah, with dozens of individuals, is federal land and off limits.

PhylumChordata
ClassReptilia
OrderSaurischia
FamilyAllosauridae
GroupDinosaur
Size8.5–10 m long
Rank (PBDB)genus· Paleobiology Database
AuthorMarsh 1877· Paleobiology Database
Classification (PBDB)Chordata › Reptilia › NO_ORDER_SPECIFIED › NO_FAMILY_SPECIFIED· Paleobiology Database
Range (PBDB)162–137 Ma· Paleobiology Database
PBDB occurrences147· Paleobiology Database

Restoration and fakes

Morrison teeth are often tip-repaired; bone is heavily consolidated and crack-filled with tinted epoxy.

Photographs

Allosaurus — Allosaurus fragilis Marsh, 1877
Allosaurus fragilis Marsh, 1877 — Smithsonian Institution (NMNHPALEO), Smithsonian Open Access, CC0
Allosaurus — Allosaurus fragilis Marsh, 1877
Allosaurus fragilis Marsh, 1877 — Smithsonian Institution (NMNHPALEO), Smithsonian Open Access, CC0
Allosaurus — Allosaurus fragilis Marsh, 1877, NON-TYPE (NHMUK PV R 12153)
Allosaurus fragilis Marsh, 1877, NON-TYPE (NHMUK PV R 12153) — © The Trustees of the Natural History Museum, London, Natural History Museum (London) Data Portal, CC BY 4.0

Age

Formations

Elsewhere

Cite this article

Stratum Study. "Allosaurus" (Taxon). Stratum Study pack 2026.09, as of 2026-09-19. https://stratum.black/study/taxa/allosaurus. Accessed 2026-09-20.

BibTeX · CSL-JSON

@misc{stratum-allosaurus,
  title        = {Allosaurus},
  author       = {{Stratum Study}},
  howpublished = {\url{https://stratum.black/study/taxa/allosaurus}},
  year         = {2026},
  note         = {Taxon article, Stratum Study pack 2026.09, as of 2026-09-19; sources: stratum, pbdb, wikidata, commons, smithsonian, nhm. Accessed 2026-09-20.}
}

Citations carry the pack version and the article's as-of date so they resolve to the same text later. The facts themselves belong to the sources listed below; cite those for the science.