Jaculinykus

Kubo et al., 2023 jak-yoo-lin-eye-kus

Named after Jaculus (a mythical jumping serpent) combined with Greek onyx/nykus (claw); meaning "Jaculus claw", referring to the hypertrophied first digit

83.6–72.2 million years ago Campanian, Late Cretaceous

Late Cretaceous stages

Jaculinykus is an extinct genus of alvarezsaurid theropod dinosaur from the Late Cretaceous Baruungoyot Formation of Mongolia. The genus contains a single species, J. yaruui, known from a nearly complete articulated skeleton including bones of the skull. Jaculinykus is notable for its unique hand, which has a hypertrophied first digit and greatly reduced second digit, which is intermediate between the tridactyl hand of Shuvuuia and monodactyl hand of Linhenykus.

Diagnosis

Dorsoventrally high narial opening of the premaxilla
Medially curved parasagittal crest on the parietal
Slender and nearly straight dentaries
Triangular-shaped deltopectoral crest separated from humeral head by a notch
Strong medial tab of metacarpal I
Weakly developed proximodorsal process of phalanx I-1
Robust medial condyle of tibia relative to fibular condyle
Sharply indented base of ascending process of astragalus

Species

Jaculinykus yaruui Kubo et al., 2023

Type species

From Mongolian 'yaruu' meaning 'speedy' or 'hasty', in reference to the animal's presumed agility.

Holotype: MPC-D 100/209 , Paleontological Center, Mongolian Academy of Sciences
Material: Nearly complete skeleton with most of the skull
Horizon: upper Baruungoyot Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality: Nemegt, Ömnögovi, Mongolia Kubo and colleagues (2023) place the holotype in the Baruungoyot-Nemegt transitional interval, within the part of it they call 'Big Red'.

References

Kubo, K.; Kobayashi, Y.; Chinzorig, T.; Tsogtbaatar, K. (2023). A new alvarezsaurid dinosaur (Theropoda, Alvarezsauria) from the Upper Cretaceous Baruungoyot Formation of Mongolia provides insights for bird-like sleeping behavior in non-avian dinosaurs. PLOS ONE 18(11): e0293801. Public Library of Science (PLoS). doi:10.1371/journal.pone.0293801 kubo2023a
Paul, G. S. (2024). The Princeton Field Guide to Predatory Dinosaurs. Princeton University Press.
Source of the appearance features.
paul2024b