Genus
Valid Extinct

Bonapartenykus

Agnolin et al. 2012

Bonapartenykus is an extinct genus of alvarezsauroid dinosaur that lived during the Late Cretaceous (Campanian–Maastrichtian) of what is now the Allen Formation of the Río Negro Province, Argentina. The genus contains a single species, Bonapartenykus ultimus, known from a partially articulated, incomplete skeleton that was found in close association to two incomplete eggs and several clusters of eggshells belonging to the oogenus Arriagadoolithus. Bonapartenykus was named in 2012. It has an estimated length of 2.5–3.3 m (8.2–10.8 ft) and weight of 43–72 kg (95–159 lb), making it the largest member of the clade Alvarezsauroidea. Additional skeletons referrable to this genus have subsequently been described.

Temporal range
Triassic
Jurassic
Cretaceous
Paleogene
Neogene
252 201 145 66 0 Ma
PBDB occurrences
3
Group
Dinosaures
Carnivore Ground dwelling, solitary Terrestrial
Bonapartenykus
click to enlarge
Skeletal reconstruction of alvarezsaurid MPCN-PV 738, referred to Bonapartenykus ultimus. © Jorge Gustavo Meso, Jonah Nathaniel Choiniere, Mattia Antonio Baiano, Stephen Louis Brusatte, Juan Ignacio Canale, Leonardo Salgado, Diego Pol, Michael Pittman · CC BY 4.0 · Wikimedia
PBDB Wikipedia
Classification
Dinosauria Unranked clade
Theropoda Unranked clade
Neotheropoda Unranked clade
Averostra Unranked clade
Tetanurae Unranked clade
Coelurosauria Unranked clade
Alvarezsauria Infraorder
Alvarezsauroidea Unranked clade
Bonapartenykus Genus
Fossil sites 3 geolocated sites
Distribution
Top countries
🇦🇷 Argentina
3
Geological formations
Allen
3
Temporal distribution
Maastrichtian (72.2–66 Ma)
3
Species (1)
Bonapartenykus ultimus 72 Ma
Images 1
Bibliography
Original description
F. L. Agnolin, J. E. Powell, and F. E. Novas, M. Kundrát. 2012. New alvarezsaurid (Dinosauria, Theropoda) from uppermost Cretaceous of north-western Patagonia with associated eggs. Cretaceous Research 35(1):33-56 DOI ↗
Bibliography (2)
J. G. Meso, J. N. Choiniere, and M. A. Baiano, S. L. Brusatte, J. I. Canale, L. Salgado, D. Pol, M. Pittman. 2025. New information on Bonapartenykus (Alvarezsauridae: Theropoda) from the Allen Formation (middle Campanian-lower Maastrichtian) of Río Negro Province, Patagonia, Argentina clarifies the Patagonykinae body plan. PLOS ONE 20(1):e0308366 DOI ↗
F. L. Agnolin, J. E. Powell, and F. E. Novas, M. Kundrát. 2012. New alvarezsaurid (Dinosauria, Theropoda) from uppermost Cretaceous of north-western Patagonia with associated eggs. Cretaceous Research 35(1):33-56 DOI ↗