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Dubreuillosaurus

Allain, 2005 dub-rhe-oo-oh-sore-us

Named for French fossil collector and preparator Pascal Dubreuil, who found the specimen, combined with Greek 'sauros' meaning 'lizard'.

168.2–165.3 million years ago Bathonian, Middle Jurassic
Middle Jurassic stages

Dubreuillosaurus is a genus of carnivorous megalosaurid theropod dinosaur from the middle Jurassic Period. Its fossils were found in France. The only named species, Dubreuillosaurus valesdunensis, was originally described as a species of Poekilopleuron, Poekilopleuron? valesdunensis, which is still formally the type species of the genus. It was later renamed Dubreuillosaurus valesdunensis when, in 2005, Allain came to the conclusion that it was not part of the genus Poekilopleuron. Its type specimen, MNHN 1998-13, is only rivalled in the number of preserved elements in this group by that of Eustreptospondylus. Dubreuillosaurus is considered to be a sister taxon of Magnosaurus. It did not show signs of insular dwarfism even though it was uncovered on an island.

Under dispute

Dubreuillosaurus valesdunensis is recovered as an afrovenatorine megalosaurid (Carrano and colleagues, 2012). Cau (2024) argues it is a junior synonym of Poekilopleuron bucklandii, its holotype representing a juvenile of that taxon; other authors retain it as a distinct genus.

Diagnosis

  1. Caudal transverse processes are spatulate distally, unlike Poekilopleuron
  2. Anterior caudal neural spines more strongly inclined posteriorly than in Poekilopleuron
  3. Mid-caudal prezygapophysis articular facets located posterior to a small triangular process unknown in other theropods
  4. Femoral head directed medioventrally at less than 90 degrees to shaft, unique among spinosauroids
  5. No extensor groove on anterior surface of distal femur end; instead a convexity is present
  6. Hypapophyses on anterior dorsal vertebrae simple and unbifurcated anteriorly, unlike Eustreptospondylus, Streptospondylus, and Lourinhanosaurus

Species

Dubreuillosaurus valesdunensis Allain, 2005

Type species

Named for the ancient battlefield of the Battle of Val-ès-Dunes (1047), fought near the discovery site in Normandy, France.

Holotype
MNHN 1998-13 , Muséum national d'Histoire naturelle
Material
Partial postcranial skeleton including cervical, dorsal, sacral, and caudal vertebrae, chevrons, ribs, gastralia, partial pectoral girdle, manual ungual, and hindlimb elements
Horizon
Pierre de Caen Bed, Calcaire de Caen Formation, Bathonian, Middle Jurassic , 168.2–165.3 million years ago
Locality
Conteville, Calvados, France

References

  1. Allain, R. (2005). The postcranial anatomy of the megalosaur Dubreuillosaurus valesdunensis(Dinosauria Theropoda) from the Middle Jurassic of Normandy, France. Journal of Vertebrate Paleontology 25(4): 850-858. Informa UK Limited. doi:10.1671/0272-4634(2005)025[0850:tpaotm]2.0.co;2 allain2005a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Source of the hip height estimate.

    jones2026c
  3. Cau, A. (2024). A Unified Framework for Predatory Dinosaur Macroevolution. Bollettino della Società Paleontologica Italiana 63(1): 1-19. doi:10.4435/BSPI.2024.08

    Argued Dubreuillosaurus is a junior synonym of Poekilopleuron, its holotype a juvenile of that taxon.

    cau2024a
  4. 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

    Recovered Dubreuillosaurus as an afrovenatorine megalosaurid in its Tetanurae phylogeny.

    carrano2012a
  5. Allain, R. (2002). Discovery of megalosaur (Dinosauria, Theropoda) in the Middle Bathonian of Normandy (France) and its implications for the phylogeny of basal Tetanurae. Journal of Vertebrate Paleontology 22(3): 548-563.

    Original description, as Poekilopleuron? valesdunensis, giving the type locality at Conteville and the horizon in the Pierre de Caen.

    allain2002a