Open Paleo

Tyrannomimus

Hattori et al., 2023 ty-RAN-o-MY-mus

From Latin 'tyrannus' meaning 'tyrant' and Latin 'mimus' meaning 'mimic', referring to its morphological similarities with tyrannosauroids.

121.4–113.2 million years ago Aptian, Early Cretaceous
Early Cretaceous stages

Tyrannomimus is an extinct genus of ornithomimosaurian theropod dinosaurs from the Early Cretaceous (Aptian age) Kitadani Formation of Japan. The type species is Tyrannomimus fukuiensis.

Under dispute

Tyrannomimus is known only from its describing analysis (Hattori and colleagues, 2023), which recovered it within Deinocheiridae as the sister taxon of Harpymimus. Because that deinocheirid position depends on the contested membership of Harpymimus and is not corroborated by an independent analysis, it is placed conservatively as a basal ornithomimosaur outside the two families.

Diagnosis

  1. Deep dorsal tympanic recess with bottom subdivided by anteroposteriorly-oriented lamina
  2. Expanded spherical cavities within prezygocentrodiapophyseal, centrodiapophyseal and postzygocentrodiapophyseal fossae
  3. Deltopectoral crest shorter than quarter of humeral length
  4. Muscle scar on anterolateral margin of deltopectoral crest
  5. Concave ventral margin of postacetabular process

Species

Tyrannomimus fukuiensis Hattori et al., 2023

Type species

Named for Fukui Prefecture, Japan, where the fossils were found.

Holotype
FPDM-V-11311 , Fukui Prefectural Dinosaur Museum
Material
Disarticulated but associated skeleton including braincase parts, dorsal/sacral/caudal vertebrae, ilium fragments
Horizon
Bonebed I Bed, Kitadani Formation, Aptian, Early Cretaceous , 121.4–113.2 million years ago
Locality
Kitadani Dinosaur Quarry, Fukui, Japan

References

  1. Azuma, Y.; Xu, X.; Shibata, M.; Kawabe, S.; Miyata, K.; Imai, T. (2016). A bizarre theropod from the Early Cretaceous of Japan highlighting mosaic evolution among coelurosaurians. Scientific Reports 6(1). Springer Science and Business Media LLC. doi:10.1038/srep20478

    Prints the Kitadani Dinosaur Quarry coordinate to the second, for a different taxon from the same quarry.

    azuma2016a
  2. Hattori, S.; Shibata, M.; Kawabe, S.; Imai, T.; Nishi, H.; Azuma, Y. (2023). New theropod dinosaur from the Lower Cretaceous of Japan provides critical implications for the early evolution of ornithomimosaurs. Scientific Reports 13(1). Springer Science and Business Media LLC. doi:10.1038/s41598-023-40804-3 hattori2023a
  3. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Source of the body length, mass, and hip height estimates.

    jones2026c