genus of troodontid theropod dinosaur
(Redirected from WDC DML 001)

Hesperornithoides is a troodontid theropod dinosaur from the Upper Jurassic Morrison Formation of western North America.

Temporal range: Late Jurassic,
Main blocks of the holotype
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: Troodontidae
Genus: Hesperornithoides
Hartman et al., 2019
H. miessleri
Binomial name
Hesperornithoides miessleri
Hartman et al., 2019


The fossil was found in Wyoming, as the site was carefully documented by the collectors.[1]


A phylogenetic analysis was presented in an abstract in the Journal of Vertebrate Paleontology in 2005. The analysis decided the specimen was a close relative of Sinornithoides.[2]


This dinosaur is very significant because it is the oldest known troodontid from North America. Until the discovery of Lori, troodontids were believed to have first originated and evolved in Asia and then migrated to North America. Most troodontids were discovered in Asia, and the previously oldest known troodontids, from the Lower Cretaceous, lived there.[3]


  1. Lovelace D.M. 2006. An Upper Jurassic Morrison Formation fire-induced debris flow: taphonomy and paleoenvironment of a sauropod (Sauropoda: Supersaurus vivianae) locality, east-central Wyoming. pp. 47–56. In: Foster J.R. and Lucas S.G. (eds) Paleontology and geology of the Upper Jurassic Morrison Formation. New Mexico Museum of Natural History and Science Bulletin 36.
  2. Hartman S; Lovelace D. and Wahl W. 2005. Phylogenetic assessment of a maniraptoran from the Morrison Formation. Journal of Vertebrate Paleontology, 25, Supplement to #3, pp 67A-68A [1] Archived 2012-07-26 at the Wayback Machine
  3. Hartman, Scott; Mortimer, Mickey; Wahl, William R.; Lomax, Dean R.; Lippincott, Jessica; Lovelace, David M. (2019). A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight. PeerJ. 7: e7247. doi:10.7717/peerj.7247.