| Named By: | Federico L. Agnolin, Jaime E. Powell, Fernando E. Novas and Martin Kundrat in 2012 |
| Time Period: | Late Cretaceous, 70 Ma[1] |
| Location: | Argentina, Patagonia |
| Size: | Estimated at 2.6 meters long |
| Diet: | Presumed insectivore |
| Fossil(s): | Partial post cranial skeleton with two eggs. Additional egg remains found in close proximity to the type specimen |
| Classification: | | Chordata | Reptilia | Dinosauria | Saurischia | Theropoda | Coelurosauria | Maniraptoriformes | Alvarezsauroidea | Alvarezsauridae | Patagonykinae | |
Bonapartenykus (named in honor of Jose Bonaparte) is a genus of alvarezsaurid theropod dinosaurs known from the Late Cretaceous (Campanian/Maastrichtian stage) of northwestern Patagonia, Argentina. The type species is B. ultimus. An adult female of B. ultimus has been discovered with two eggs that may have still been inside its oviducts, although some evidence suggests that the eggs may have been incubated in a nest. The size of the adult female has been estimated as at least 8.5 feet (2.6 m), and the weight of Bonapartenykus has been estimated as 100 pounds (45 kg). Its diet probably consisted of insects. Paleontologist Fernando Novas compared its bones to those of the nandu, a modern-day Patagonian flightless bird.
The eggs of Bonapartenykus were considered unique enough for them to be given a new parataxonomic name, Arriagadoolithus, which was classified in a new oofamily, the Arriagadoolithidae, so named for the owner of the site where the discovery was made.