Open Paleo

Acrocanthosaurus

Stovall & Langston, 1950 AK-roh-KAN-thuh-SOR-uhs /ˌækroʊˌkænθəˈsɔːrəs/

From Greek 'akros' meaning 'high', 'akantha' meaning 'spine', and 'sauros' meaning 'lizard', referring to its high-spined vertebrae.

121.4–100.5 million years ago Aptian–Albian, Early Cretaceous
Early Cretaceous stages

Acrocanthosaurus is a genus of carcharodontosaurid dinosaurs that existed in what is now North America during the Barremian and early Cenomanian stages of the Early Cretaceous and Late Cretaceous, from 125 to 99.6 million years ago. Like most dinosaur genera, Acrocanthosaurus contains only a single species, A. atokensis. It had a continent-wide range, with fossil remains known from the U.S. states of Oklahoma, Texas, and Wyoming in the west and Maryland in the east. However, most of these remains are assigned to the species based on the assumption that Acrocanthosaurus is the only large carcharodontosaurid from North America during this time, and the possibility exists that some referred specimens could represent distinct taxa.

Diagnosis

  1. Massive and greatly elongated neural spines throughout cervical and dorsal vertebrae
  2. Medial caudal vertebrae with supplementary (double) neural processes
  3. Anterior chevrons closed proximally by transverse bar and bearing an upward-projecting anterior process on each ramus
  4. Tibia strongly bowed outward, more so than in any known allied genus
  5. Metatarsal III somewhat constricted proximally by lateral elements (metatarsals II and IV)

Species

Acrocanthosaurus atokensis Stovall & Langston, 1950

Type species

Named for Atoka County in Oklahoma, where the original specimens were found.

Holotype
OMNH 10146 , Oklahoma Museum of Natural History
Material
Partial skeleton with skull-roof and braincase elements and partial left mandible, nine cervical plus dorsal and caudal vertebrae, ribs, gastralia, coracoid, pubes, ischium, and fragmentary hindlimb bones
Horizon
Antlers Formation, Aptian–Albian, Early Cretaceous , 121.4–100.5 million years ago
Locality
Cochran farm, Oklahoma, United States

Synonyms of the genus

Name Type Reason
Acracanthus nomen ex dissertatione Name appears in a dissertation, which does not meet ICZN publication requirements; referable to Acrocanthosaurus. Per Olshevsky's Dinosaur Genera List.

Notable specimens

  • “Fran”

    NCSM 14345 North Carolina Museum of Natural Sciences most complete

    Most complete and largest known skeleton, with the only complete skull and forelimb. Its braincase enabled CT brain and inner-ear reconstruction, and the intact forelimb allowed the first study of arm range of motion and predatory function.

    Currie & Carpenter (2000)

  • USNM 466054

    National Museum of Natural History, Smithsonian Institution Found 1992 range extension

    Subadult identified in 2024 as the first definitive record of the genus from eastern North America. The most completely known theropod from the Arundel Formation, previously misidentified as an ornithomimosaur, and the smallest known individual of the genus.

    Carrano (2024)

  • SMU 74646

    Shuler Museum of Paleontology, Southern Methodist University historic

    A partial skeleton missing most of the skull from the Twin Mountains Formation of Texas, one of the first much more complete specimens described in the 1990s; now part of the Fort Worth Museum of Science and History collection.

    Harris (1998)

  • UM 20796

    Museum of Paleontology, University of Michigan Found 2008 by Michael D. D'Emic range extension

    A juvenile partial skeleton that established the presence of the genus in the Cloverly Formation of Wyoming in 2012. Found near the shoulder blade of a Sauroposeidon in a Bighorn Basin bonebed.

    D'Emic et al. (2012)

References

  1. Stovall, J. W.; Langston, W. (1950). Acrocanthosaurus atokensis, a New Genus and Species of Lower Cretaceous Theropoda from Oklahoma. American Midland Naturalist 43(3): 696. JSTOR. doi:10.2307/2421859 stovall1950a
  2. Harris, J. D. (1998). A reanalysis of Acrocanthosaurus atokensis, its phylogenetic status, and paleobiogeographic implications, based on a new specimen from Texas. New Mexico Museum of Natural History and Science Bulletin 13: 1-75. harris1998a
  3. Currie, P. J.; Carpenter, K. (2000). A new specimen of Acrocanthosaurus atokensis (Theropoda, Dinosauria) from the Lower Cretaceous Antlers Formation (Lower Cretaceous, Aptian) of Oklahoma, USA. Geodiversitas 22(2): 207-246. currie2000a
  4. D'Emic, M. D.; Melstrom, K. M.; Eddy, D. R. (2012). Paleobiology and geographic range of the large-bodied Cretaceous theropod dinosaur Acrocanthosaurus atokensis. Palaeogeography, Palaeoclimatology, Palaeoecology 333-334: 13-23. doi:10.1016/j.palaeo.2012.03.003 d'emic2012a
  5. Carrano, M. T. (2024). First definitive record of Acrocanthosaurus (Theropoda: Carcharodontosauridae) in the Lower Cretaceous of eastern North America. Cretaceous Research 157: 105814. doi:10.1016/j.cretres.2023.105814 carrano2024a
  6. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Source of the appearance features.

    jones2026c