Open Paleo

Trierarchuncus

Fowler et al., 2020 tree-uh-rar-chun-kuss

Named from Greek meaning 'captain hook,' in reference to its single-clawed hands

72.2–66.0 million years ago Maastrichtian, Late Cretaceous
Late Cretaceous stages

Trierarchuncus is a monotypic genus of alvarezsaurid theropod which includes a single species, Trierarchuncus prairiensis, mainly known from fossils found in deposits of the Hell Creek Formation in Montana. It is the youngest known alvarezsaurid and one of the last non-avian dinosaurs, going extinct during the Cretaceous-Paleogene extinction event, which occurred approximately 66 million years ago.

Diagnosis

  1. Ventral sulcus extends proximally to reach distal extent of ventral foramina but does not extend between them
  2. Deep lateral embayment of ventral foramina displaced strongly medially, width of embayment >10% of total ungual width
  3. Extensive rugosity developed as spur-like projections over proximal end
  4. Flexor tubercle formed into two small mounds
  5. Slight lateral pinching of proximal articular end, forming weak butterfly shape
  6. Wide notch on distal radius between proximal extension of aponeurosis tubercle and ulnar suture

Species

Trierarchuncus prairiensis Fowler et al., 2020

Type species

From Latin '-ensis' meaning 'from', combined with 'prairie', referring to the plains of eastern Montana where the remains were discovered.

Holotype
MOR 6622 , Museum of the Rockies
Material
A manual ungual (MD-I-2).
Horizon
Hell Creek Formation, Maastrichtian, Late Cretaceous , 72.2–66.0 million years ago
Locality
HC-557, Montana, United States

References

  1. Fowler, D. W.; Wilson, J. P.; Freedman Fowler, E. A.; Noto, C. R.; Anduza, D.; Horner, J. R. (2020). Trierarchuncus prairiensis gen. et sp. nov., the last alvarezsaurid: Hell Creek Formation (uppermost Maastrichtian), Montana. Cretaceous Research 116. Elsevier BV. doi:10.1016/j.cretres.2020.104560 fowler2020b