Open Paleo

Janenschia

Wild, 1991 yah-NEN-shee-a

Named in honor of German paleontologist Werner Janensch, who conducted extensive research on dinosaurs from the Tendaguru Formation of Tanzania

154.8–137.1 million years ago Kimmeridgian–Berriasian, Late Jurassic–Early Cretaceous
Late Jurassic and Early Cretaceous stages

Janenschia is a genus of large herbivorous sauropod dinosaur from the Late Jurassic (around 155 to 145 million years ago) Tendaguru Formation of Lindi Region, Tanzania.

Under dispute

The hindlimb holotype of Janenschia is recovered as a non-neosauropodan eusauropod, sister to Haestasaurus (Mannion and colleagues, 2019), but other studies place it within basal Macronaria (Ren and colleagues, 2023) or Turiasauria. Jones (2026) regards its placement as very uncertain.

Diagnosis

  1. Astragalus low and platy, unlike that of all other sauropods
  2. Anterior caudal vertebrae with strongly convex posterior and strongly concave anterior articular surfaces, lacking pleurocoels
  3. Middle caudal vertebrae strongly pinched laterally, with weakly biconvex articular surfaces and a high-elliptical cross-section
  4. Anterior dorsal vertebrae with nearly completely reduced neural spines and very robust diapophyses
  5. Manus phalangeal formula 2-2-1-1-1, with only the first digit bearing a very large claw
  6. Pes with clawed first three toes, phalangeal formula 2-3-3-2-1, and a short, proximally very broad metatarsal V

Species

Janenschia robusta (Fraas, 1908)

Type species

First named as Gigantosaurus robustus

From Latin 'robustus' meaning 'robust' or 'sturdy', inspired by the heavy build of the animal.

Holotype
SMNS 12144 , Staatliches Museum für Naturkunde
Material
Distal articular end of the right femur, right tibia and fibula, right astragalus, and right metatarsals I-V with corresponding phalanges I-V
Horizon
Upper Dinosaur Member, Tendaguru Formation, Kimmeridgian–Berriasian, Late Jurassic–Early Cretaceous , 154.8–137.1 million years ago
Locality
Quarry B, Lindi, Tanzania

Synonyms

  • Gigantosaurus robustus reassigned

    Originally described as Gigantosaurus robustus; the genus name was preoccupied, and the species was reassigned to Tornieria and later to Janenschia.

  • Tornieria robusta reassigned

    Combination used after Sternfeld (1911) transferred the species to Tornieria; Wild (1991) found it generically distinct and erected Janenschia.

Synonyms of the genus

Name Type Reason
Nteregosaurus nomen nudum Informal name used for material now considered referable to Janenschia.

References

  1. Fraas, E. (1908). Dinosaurierfunde in Ostafrika [Dinosaur finds in East Africa]. Jahreshefte des Vereins für Vaterländische Naturkunde in Württemberg 64: 84-86.

    In German. Names the species as Gigantosaurus robustus in a report of Fraas's talk; Gigantosaurus was preoccupied by Seeley, 1869.

    fraas1908a
  2. Fraas, E. (1908). Ostafrikanische Dinosaurier [East African dinosaurs]. Palaeontographica 55: 105-144.

    In German. Describes the type material (Skeleton B, holotype SMNS 12144, a right hindlimb) as Gigantosaurus robustus.

    fraas1908b
  3. Sternfeld, R. (1911). Zur Nomenklatur der Gattung Gigantosaurus Fraas [On the nomenclature of the genus Gigantosaurus Fraas]. Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin 8: 398.

    In German. Coins the replacement genus Tornieria for the preoccupied Gigantosaurus Fraas, 1908.

    sternfeld1911a
  4. Wild, R. (1991). Janenschia n. g. robusta (E. Fraas 1908) pro Tornieria robusta (E. Fraas 1908) (Reptilia, Saurischia, Sauropodomorpha) [Janenschia n. g. robusta (E. Fraas 1908) for Tornieria robusta (E. Fraas 1908) (Reptilia, Saurischia, Sauropodomorpha)]. Stuttgarter Beiträge zur Naturkunde, Serie B (Geologie und Paläontologie) 173: 1-4. wild1991a
  5. Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.

    Source of the mass estimate.

    paul2024a
  6. Mannion, P. D.; Upchurch, P.; Schwarz, D.; Wings, O. (2019). Taxonomic affinities of the putative titanosaurs from the Late Jurassic Tendaguru Formation of Tanzania: phylogenetic and biogeographic implications for eusauropod dinosaur evolution. Zoological Journal of the Linnean Society 185(3): 784-909. Oxford University Press (OUP). doi:10.1093/zoolinnean/zly068

    Recovered the Janenschia hindlimb holotype as a non-neosauropodan eusauropod near Haestasaurus.

    mannion2019a
  7. Ren, X. X.; Jiang, S.; Wang, X. R.; Peng, G. Z.; Ye, Y.; Jia, L.; You, H. L. (2023). Re-examination of Dashanpusaurus dongi (Sauropoda: Macronaria) supports an early Middle Jurassic global distribution of neosauropod dinosaurs. Palaeogeography, Palaeoclimatology, Palaeoecology 610: 111318. doi:10.1016/j.palaeo.2022.111318

    Recovered Janenschia within basal Macronaria.

    ren2023a
  8. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Reports turiasaur and basal macronarian placements for Janenschia.

    jones2026b