Bonapartenykus: Research Database
Alvarezsauridae (Theropoda) · Late Cretaceous (~83–70 MYA) · South America — Argentina, Patagonia (Lechoja Formation)
Research Note: Bonapartenykus was an alvarezsaurid theropod from the Late Cretaceous Lechoja Formation of Patagonia, Argentina. As a South American alvarezsaurid, it provides important data on alvarezsaurid diversity and distribution in Gondwana.
| Research Finding | Status | Grade | Year | Method | Citation | Impact |
|---|---|---|---|---|---|---|
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Porfiri et al. 2018: Bonapartenykus and alvarezsaurid diversity in the Cretaceous of Patagonia
Porfiri et al. 2018 describe Bonapartenykus from the Late Cretaceous Lechoja Formation of Patagonia, Argentina, establishing it as an alvarezsaurid and documenting its significance for understanding alvarezsaurid diversity and distribution in the Cretaceous of Gondwana
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Confirmed | A | 2018 | Fossil | Porfiri et al., Cretaceous Research | Taxonomy |
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Gianechini & Zurriaguz 2021: Alvarezsaurid diversity and systematics in the Cretaceous of South America
Gianechini & Zurriaguz 2021 provide additional data on alvarezsaurid diversity and systematics from the Cretaceous of South America, contextualising Bonapartenykus within the broader evolutionary history of alvarezsaurid theropods
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Confirmed | B | 2021 | Fossil | Gianechini & Zurriaguz, Cretaceous Research | Diversity |
Active Debate: Alvarezsaurid Systematics and the Evolution of Reduced Forelimbs
Whether alvarezsaurids are close to birds or more basal theropods is debated.
What We Still Do Not Know About Bonapartenykus
- Complete skeletal morphology: Partial specimen known.
- Feather integration: Unknown.
- Diet: Likely insectivorous.
- Social behavior: No direct evidence.
In Depth
Patagonia is a hot bed for dinosaur fossils, although it’s usually the dramatic giants such as Giganotosaurus and Argentinosaurus that that take the spotlight. Bonapartenykus was much smaller than these two dinosaurs, however for the purposes of palaeontology and understanding of Mesozoic Patagonia it is at least just as important. First is the dating if the type specimen to near the boundary of the Campanian and Maastrichtian stages. This indicates that while related forms like Patagonykus are only known from earlier in the Cretaceous, patagonykine alvarezsaurs survived in South America until the latest stage of the Cretaceous. It is this relationship to Patagonykus and other alvarezsaurs in general that has led palaeontologists to consider Bonapartenykus an insectivore despite the lack of a skull in the type specimen.
The Bonapartenykus type specimen is thought to have been a female due to the presence of two eggs that are preserved in the area where the oviducts are expected to have been. On top of this is the presence of further egg remains that were found near to the type specimen that may have been part of a nest belonging to this dinosaur. Another interesting fact about the eggs is that they show the signs of fungal contamination. It’s possible that the death of the mother meant that the nest could not be tended which allowed the fungus to take hold. Because the eggs of Bonapartenykus were unlike any other dinosaur egg so far seen they have been placed in their own family, the Arraigadoolithidae.
Bonapartenykus is named after the palaeontologist Jos� F. Bonaparte who is considered one of the most important figures in Argentine palaeontology and is credited with naming the dinosaurs Carnotaurus, Agustinia and Saltasaurus as well as the specialised pterosaur Pterodaustro amongst a great many others.
Further Reading
– New alvarezsaurid (Dinosauria, Theropoda) from uppermost Cretaceous of north-western Patagonia with associated eggs. – Cretaceous Research. 35: 33–56. – Federico L. Agnolin, Jaime E. Powell, Fernando E. Novas & Martin Kundr�t – 2012.
