Open Paleo

Allosauridae

Marsh, 1878 Type genus Allosaurus

Its genera lived 154.8–143.1 million years ago Late Jurassic
Late Jurassic stages

Allosauridae is a family of medium to large, bipedal, carnivorous allosauroid theropod dinosaurs from the Late Jurassic, best known from Allosaurus. Their overall anatomy is fairly typical of other theropods, which has long made the family's precise membership difficult to define; Saurophaganax has been attributed to the group, though Danison and colleagues (2024) refer some of its distinguishing elements to a diplodocid sauropod, base a new species of Allosaurus on other material referred to it, and treat Saurophaganax maximus as a nomen dubium. Allosaurid skulls carry prominent horns or hornlets on the lacrimal bones above the eyes that would have been sheathed in keratin, and show marked cranial kinesis, with flexible joints that cushioned the skull and let the animals gape their jaws very wide. Like most theropods they had short forelimbs relative to their hindlimbs, with three-fingered hands bearing long, strongly curved claws suited to raking and grasping prey. The pubis is greatly elongated and ends in a broad "foot" that likely helped support the body's weight when the animal rested in a crouch.

Diagnosis

  1. Prominent lacrimal horns or hornlets above the eyes
  2. Strongly downturned paroccipital processes terminating well ventral to the basal tubera
  3. Shortened quadrate relative to other allosauroids
  4. Expanded distal end of the scapula

Genera placed directly in Allosauridae

  • Allosaurus Marsh, 1877 Kimmeridgian–Tithonian (154.8–143.1 Ma)United States
  • Saurophaganax Disputed Chure, 1995 Kimmeridgian–Tithonian (154.8–143.1 Ma)United States

References

  1. Marsh, O. C. (1878). Notice of new dinosaurian reptiles. American Journal of Science s3-15(87): 241-244. American Journal of Science (AJS). doi:10.2475/ajs.s3-15.87.241

    Named the family Allosauridae.

    marsh1878a
  2. Carrano, M. T.; Benson, R. B. J.; Sampson, S. D. (2012). The phylogeny of Tetanurae (Dinosauria: Theropoda). Journal of Systematic Palaeontology 10(2): 211-300. Informa UK Limited. doi:10.1080/14772019.2011.630927

    Revised Tetanurae, restricting Allosauridae to Allosaurus and Saurophaganax.

    carrano2012a
  3. Currie, P. J.; Zhao, X. J. (1993). A new carnosaur (Dinosauria, Theropoda) from the Jurassic of Xinjiang, People's Republic of China. Canadian Journal of Earth Sciences 30(10): 2037-2081. Canadian Science Publishing. doi:10.1139/e93-179

    Source of the cranial and pectoral diagnostic characters.

    currie1993c
  4. Danison, A. D.; Wedel, M. J.; Barta, D. E.; Woodward, H. N.; Flora, H. M.; Lee, A. H.; Snively, E. (2024). Chimerism of specimens referred to Saurophaganax maximus reveals a new species of Allosaurus (Dinosauria, Theropoda). Vertebrate Anatomy Morphology Palaeontology 12(1): 81-114. doi:10.18435/vamp29404

    Referred some elements used to diagnose Saurophaganax to a diplodocid, treated the name as a nomen dubium, and named a new species of Allosaurus for other referred material.

    danison2024a