Open Paleo

Diplodocoidea

Marsh, 1884 Type genus Diplodocus

Its genera lived 184.2–89.8 million years ago Early Jurassic–Late Cretaceous

Diplodocoidea is a superfamily of sauropod dinosaurs that includes some of the longest animals ever to have lived. It brings together the narrow-snouted rebbachisaurids, the short-necked, high-spined dicraeosaurids, and the extremely elongate diplodocids, along with basal forms such as Haplocanthosaurus. Most diplodocoids had very long necks and long, whip-like tails, and among their ranks are slender giants like Supersaurus, Diplodocus, and Apatosaurus. The dicraeosaurids are the only known sauropods to have re-evolved a short neck, presumably an adaptation for feeding close to the ground, a trend taken to the extreme in the highly specialized Brachytrachelopan. Diplodocoids are distinguished by slender, pencil-like teeth restricted to the front of the jaws and squared-off snouts, and they had the highest tooth replacement rates of any vertebrates, with some forms erupting new teeth roughly every month.

Diagnosis

  1. Tooth crowns slender and subcylindrical (pencil-like), restricted to the anterior part of the jaws
  2. External nares retracted to a position dorsal to or behind the orbits
  3. Elevated tooth replacement rates with multiple replacement teeth per alveolus
  4. Squared-off (rather than rounded) anterior margin of the snout in dorsal view

Clades within Diplodocoidea

Genera placed directly in Diplodocoidea

  • Amphicoelias Cope, 1877 Kimmeridgian–Tithonian (154.8–143.1 Ma)United Statesincertae sedisunder dispute

References

  1. Marsh, O. C. (1884). Principal characters of American Jurassic dinosaurs; Part VII, On the Diplodocidae, a new family of the Sauropoda. American Journal of Science 27(158): 161-167. doi:10.2475/ajs.s3-27.158.161

    Named the family Diplodocidae, from which the superfamily Diplodocoidea takes its authorship by coordination.

    marsh1884b
  2. Wilson, J. A.; Sereno, P. C. (1998). Early evolution and higher-level phylogeny of sauropod dinosaurs. Memoir (Society of Vertebrate Paleontology) 5: 1-68. doi:10.2307/3889325

    Provided the stem-based phylogenetic definition of Diplodocoidea.

    wilson1998a