Open Paleo

Kaatedocus

Tschopp & Mateus, 2012 kaht-uh-doh-kus

From Crow language 'kaate' meaning 'small' combined with Greek 'dokos' meaning 'beam', referring to the vertebrae; the name means 'small beam', alluding to its relatively small size compared to other diplodocids.

154.8–149.2 million years ago Kimmeridgian, Late Jurassic
Late Jurassic stages

Kaatedocus is a genus of flagellicaudatan sauropod known from the middle Late Jurassic (Kimmeridgian stage) of northern Wyoming, United States. It is known from well-preserved skull and cervical vertebrae which were collected in the lower part of the Morrison Formation. The type and only species is Kaatedocus siberi, described in 2012 by Emanuel Tschopp and Octávio Mateus.

Under dispute

The family-level placement of Kaatedocus is disputed. Tschopp and Mateus (2012) and Tschopp and colleagues (2015) recovered it as a diplodocine diplodocid, sister to Barosaurus, and the Princeton Encyclopedia (Jones, 2026) follows this view. Whitlock and Wilson Mantilla (2020) instead recovered it as the basalmost dicraeosaurid on cranial characters, a result reproduced when Kaatedocus was added to an independent matrix; under that hypothesis the diplodocid characters previously cited for it are reinterpreted as more general flagellicaudatan features.

Diagnosis

  1. U-shaped notch separating the frontals anteriorly
  2. Squamosals restricted to the post-orbital region
  3. Postparietal foramen present
  4. Narrow, sharp and distinct sagittal nuchal crest on supraoccipital
  5. Closed or very reduced preantorbital fenestra
  6. At least 12 maxillary and dentary teeth not restricted to anteriormost jaw
  7. Short mid-cervical centra with elongation index less than 4
  8. Rugose tuberosity on anterodorsal corner of lateral surface of posterior cervical vertebrae
  9. Posterior cervical neural spines narrowly diverging to subparallel

Species

Kaatedocus siberi Tschopp & Mateus, 2012

Type species

Named for Hans-Jakob Siber, founder of the Swiss Aathal Dinosaur Museum and leader of the excavations that recovered the holotype.

Holotype
SMA 0004 , Sauriermuseum Aathal
Material
Partial skull with both maxillae, both frontals, both postorbitals, both quadrates, both squamosals, complete braincase, both dentaries, and cervical series from proatlas to CV 14.
Horizon
Morrison Formation, Kimmeridgian, Late Jurassic , 154.8–149.2 million years ago
Locality
Howe Quarry, Wyoming, United States

Notable specimens

  • AMNH FARB 7530

    American Museum of Natural History Found 1934 by Barnum Brown historic

    Recovered in 1934 by Barnum Brown's AMNH team at the Howe Quarry near Shell, Wyoming. One of only about 10% of the Howe bones to survive a 1940s museum fire, it was long interpreted as Barosaurus before being reinterpreted in 2015 as Kaatedocus.

    Tschopp et al. (2015)

References

  1. Tschopp, E.; Mateus, O. (2012). The skull and neck of a new flagellicaudatan sauropod from the Morrison Formation and its implication for the evolution and ontogeny of diplodocid dinosaurs. Journal of Systematic Palaeontology 11(7): 853-888. Informa UK Limited. doi:10.1080/14772019.2012.746589 tschopp2012a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the mass and hip height estimates, and the appearance features.

    jones2026b
  3. Tschopp, E.; Mateus, O.; Benson, R. B. J. (2015). A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda). PeerJ 3: e857. PeerJ. doi:10.7717/peerj.857 tschopp2015a
  4. Whitlock, J. A.; Wilson Mantilla, J. A. (2020). The Late Jurassic sauropod dinosaur 'Morosaurus' agilis Marsh, 1889 reexamined and reinterpreted as a dicraeosaurid. Journal of Vertebrate Paleontology 40(6): e1780600. Informa UK Limited. doi:10.1080/02724634.2020.1780600

    Recovered Kaatedocus as the basalmost dicraeosaurid on cranial characters.

    whitlock2020a