Open Paleo

Dicraeosaurus

Janensch, 1914 die-KREE-o-SAWR-us

From Greek dikraios (δικραιος), 'bifurcated' or 'double-headed', + Greek sauros, 'lizard'; means 'bifurcated lizard', referring to the forked neural spines on its vertebrae

154.8–143.1 million years ago Kimmeridgian–Tithonian, Late Jurassic
Late Jurassic stages

Dicraeosaurus is a genus of diplodocoid sauropod dinosaur that lived in what is now Lindi Region, Tanzania during the late Jurassic period. The genus was named for the neural spines on the back of its neck. The first fossil was described by paleontologist Werner Janensch in 1914.

Diagnosis

  1. Cervical vertebrae with two tall, completely independent (divided to base) neural spines
  2. Thoracic dorsal vertebrae with very tall bifurcated neural spines divided throughout their entire height
  3. Diapophyses of trunk vertebrae directed steeply obliquely upward
  4. Posterior trunk vertebral bodies lacking lateral pleurozentral pits
  5. Cervical vertebral body strongly laterally compressed, narrowing anteriorly to a thin wall behind the articular head

Species (2)

Dicraeosaurus hansemanni Janensch, 1914

Type species

Named in honor of the German scientist and politician David von Hansemann.

Holotype
MB.R.4886 , Museum für Naturkunde, Berlin
Material
Skeleton including cervical, trunk, and caudal vertebrae and a femur
Horizon
Middle Dinosaur Member, Tendaguru Formation, Kimmeridgian–Tithonian, Late Jurassic , 154.8–143.1 million years ago
Locality
Kindope, Lindi, Tanzania

Dicraeosaurus sattleri Janensch, 1914

Honors W. B. Sattler, who discovered the Tendaguru fossil site and supported the expedition.

Horizon
Upper Dinosaur Member, Tendaguru Formation, Kimmeridgian–Tithonian, Late Jurassic , 154.8–143.1 million years ago
Locality
Locality M, Lindi, Tanzania
Diagnosis
  1. Trunk vertebrae more slender and lightly built, with a smaller, less massive centrum.
  2. Neural spines of the trunk vertebrae narrower but relatively longer and proportionally higher than in D. hansemanni (bifurcated in the same manner).
  3. Diapophyses of the trunk vertebrae less elongate relative to centrum length.
  4. Anterior caudal vertebrae with proportionally higher neural spines.
  5. Dorsal ribs slimmer and lighter, with thinner, weaker distal ends.
  6. Chevrons lighter, slimmer, and more strongly curved.
  7. Pubis and femur more slender and lightly built.

Synonyms of the genus

Name Type Reason
Issasaurus nomen nudum Informal name; never met ICZN requirements for formal publication and is treated as referable to Dicraeosaurus. Per Olshevsky's Dinosaur Genera List.
Mtotosaurus nomen nudum Informal name; never met ICZN requirements for formal publication and is treated as referable to Dicraeosaurus. Per Olshevsky's Dinosaur Genera List.
Nyororosaurus nomen nudum Informal name; never met ICZN requirements for formal publication and is treated as referable to Dicraeosaurus. Per Olshevsky's Dinosaur Genera List.
Selimanosaurus nomen nudum Informal name; never met ICZN requirements for formal publication and is treated as referable to Dicraeosaurus. Per Olshevsky's Dinosaur Genera List.

References

  1. Janensch, W. (1914). Übersicht über die Wirbeltierfauna der Tendaguru-Schichten [Overview of the vertebrate fauna of the Tendaguru beds]. Archiv für Biontologie 3: 81-110. janensch1914a
  2. Bussert, R.; Heinrich, W. D.; Aberhan, M. (2009). The Tendaguru Formation (Late Jurassic to Early Cretaceous, southern Tanzania): definition, palaeoenvironments, and sequence stratigraphy. Fossil Record 12(2): 141-174. doi:10.5194/fr-12-141-2009

    Renames the Saurian Beds as a series of six members, listing Dicraeosaurus hansemanni from the Middle Dinosaur Member and D. sattleri from the Upper Dinosaur Member.

    bussert2009a
  3. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the hip height estimate, and the appearance features.

    jones2026b
  4. Janensch, W. (1929). Die Wirbelsäule der Gattung Dicraeosaurus [The vertebral column of the genus Dicraeosaurus]. Palaeontographica, Supplement 7 1. Reihe, Teil 2: 37-133.

    Detailed comparative osteology of the vertebral column of both Dicraeosaurus species; source of the D. sattleri differential diagnosis.

    janensch1929a