Open Paleo

Hypnovenator

Kubota et al., 2024 HIP-no-VEN-uh-tuh

Sleep hunter; from Greek hypnos (sleep) and Latin venator (hunter), possibly referring to its nocturnal hunting behavior

113.2–100.5 million years ago Albian, Early Cretaceous
Early Cretaceous stages

Hypnovenator is an extinct genus of troodontid theropod dinosaurs from the Early Cretaceous (Albian) Ohyamashimo Formation of Japan. The genus contains a single species, Hypnovenator matsubaraetoheorum, known from a partial skeleton. Hypnovenator is the only troodontid currently known from Japan, and it represents the oldest definitive member of the subgroup Troodontinae.

Under dispute

Hypnovenator was described as the oldest and a basal member of Troodontinae, forming a clade with Gobivenator (Kubota and colleagues, 2024), the placement followed. It has not yet been tested by independent analyses.

Diagnosis

  1. Pair of proximodistally extended depressions on proximodorsal surface of manual phalanx I-1
  2. Long dorsal and ventral proximal lips on manual phalanx III-2 for tight articulation with phalanx III-1
  3. Proximodistally longitudinal medial ridge on anterior surface of femur proximal to medial condyle
  4. Distorted distal condyles with widely convex distoventral margin on pedal phalanx III-3
  5. Thickest portion of ulna distal end near middle portion (unique combination feature)
  6. Angle less than 11 degrees between anterior edge of cnemial crest and anterior edge of tibial shaft

Species

Hypnovenator matsubaraetoheorum Kubota et al., 2024

Type species

Named for Kaoru Matsubara and Takaharu Ohe, the discoverers of the Hypnovenator holotype.

Holotype
MNHAH D1033340 , Museum of Nature and Human Activities
Material
Partial skeleton: caudal vertebrae, chevron, ribs, gastralia, left arm (humerus, radius, ulna, carpal, metacarpals, phalanges, unguals), partial left and right leg elements
Horizon
middle Ohyamashimo Formation, Albian, Early Cretaceous , 113.2–100.5 million years ago
Locality
Nishikosa, Hyōgo, Japan Kubota and colleagues (2024) assign the holotype to the middle of the formation by correlation rather than by a measured section at the site.

References

  1. Kubota, K.; Kobayashi, Y.; Ikeda, T. (2024). Early Cretaceous troodontine troodontid (Dinosauria: Theropoda) from the Ohyamashimo Formation of Japan reveals the early evolution of Troodontinae. Scientific Reports 14(1). Springer Science and Business Media LLC. doi:10.1038/s41598-024-66815-2 kubota2024a