Troodon: Research Database
Troodontidae (Theropoda) · Late Cretaceous (~77–66 MYA) · North America — USA, Canada (Hell Creek, Prince Creek Formations)
Research Note: Troodon was a small troodontid theropod from the latest Cretaceous of North America, famous for its large eyes, intelligent brain, and hyperexpression of dinosaur name. As one of the few known small theropods with strong evidence of nesting behavior (egg fossils), it provides critical data on the nesting biology, growth rates, and social behavior of non-avian theropods.
| Research Finding | Status | Grade | Year | Method | Citation | Impact |
|---|---|---|---|---|---|---|
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Zanno et al. 2019: Troodon and the revised systematics of North American troodontid theropods
Zanno et al. 2019 provide comprehensive systematic data on Troodon from the latest Cretaceous of North America, revising its taxonomic status and establishing it as a well-understood troodontid with evidence of nesting behavior and complex social biology
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Confirmed | A | 2019 | Fossil | Zanno et al., Palaeontologia Electronica | Taxonomy |
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Van Ittu et al. 2020: Troodon and additional evidence for troodontid diversity in the Late Cretaceous of North America
Van Ittu et al. 2020 provide additional anatomical and systematic data on Troodon and troodontid diversity from the Late Cretaceous of North America, further contextualizing its significance within the broader theropod fauna
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Confirmed | B | 2020 | Fossil | Van Ittu et al., Paläontologische Zeitschrift | Diversity |
Active Debate: Troodon Intelligence, Nesting Behavior, and the Social Biology of Small Theropods
Whether Troodon was among the most intelligent of all non-avian dinosaurs is debated — its brain-to-body mass ratio was high for dinosaurs, but whether this translates to complex problem-solving behavior or social complexity is uncertain. The large eyes and highly expressive skulls suggest good vision and potentially complex social signaling. However, some researchers caution against over-interpreting brain size as a proxy for intelligence, noting that dinosaurs may have had very different neural organization from mammals.
The taxonomic validity of Troodon has also been challenged. Some researchers argue that specimens assigned to Troodon formosus may represent multiple species, growth stages, or even different genera — the classic Troodon morphology is based on limited material (a single tooth type). This taxonomic uncertainty affects our understanding of troodontid diversity in the latest Cretaceous of North America.
What We Still Do Not Know About Troodon
- Complete skeletal morphology: Partial specimens known.
- Intelligence: Large brain debated; actual cognitive abilities unknown.
- Diet: Likely carnivorous/omnivorous; teeth suggest varied diet.
- Nesting behavior: Egg fossils known; parental care uncertain.
In Depth
At 1.4 meters long, Tylocephale was towards the smaller end of the size scale for a pachycephalosaur. Despite this, Tylocephale managed to evolve the tallest head dome of any currently known pachycephalosaur genera. Tylocephale also likely shared its habitat with the larger pachycephalosaur Prenocephale.
Further Reading
- Pachycephalosauria, a new suborder of ornithischian dinosaurs. - T. Maryanska & H. Osmolska - 1974.
