Allosaurus fossil map
Where fossils of Allosaurus have been found, shown on the Earth as it looked about 145 million years ago and on today’s map.
Dots are fossil collections recorded in the Paleobiology Database. The “then” view moves today’s fossil sites back to their positions 145 million years ago (the time slice nearest the median age of the fossils) using the Merdith et al. (2021) plate model; positions are approximate. Open on the timeline map →
| Group | Theropods |
|---|---|
| Lived | 161.5–137.05 million years ago (Oxfordian to Berriasian) |
| Periods | Jurassic, Cretaceous |
| Named by | Marsh 1877 |
| Fossil records | 147 occurrences at 101 locations (PBDB) |
| Found in | United States, Portugal, France, Germany |
| Rock formations | Morrison, Alcobaça, Lourinhã, txn:NF, Lepidotus Beds |
About Allosaurus
Allosaurus ( AL-o-SAWR-us) is a genus of theropod dinosaur that lived 155 to 143 million years ago during the late Jurassic period (latest Oxfordian to latest Tithonian ages). The first fossil remains that could definitively be ascribed to this genus were described in 1877 by Othniel C. Marsh. The name "Allosaurus" means "different lizard", alluding to its lightweight vertebrae, which Marsh believed were unique. The genus has a very complicated taxonomy and includes at least three valid species, the best known of which is A. fragilis. The bulk of Allosaurus remains come from North America's Morrison Formation, with material also known from the Alcobaça, Bombarral, and Lourinhã formations in Portugal. It was known for over half of the 20th century as Antrodemus, but a study of the abundant remains from the Cleveland-Lloyd Dinosaur Quarry returned the name "Allosaurus" to prominence. As one of the first well-known theropod dinosaurs, it has long attracted attention outside of paleontological circles.
Text in “About” is quoted from the Wikipedia article Allosaurus (revision 1381168316), licensed under CC BY-SA 4.0; introduction excerpted verbatim, formatting removed. Ages, family, authority and fossil records: Paleobiology Database, accessed 22 October 2026. Ages are those of the rock layers the fossils were found in. Wikidata: Q14400.
