Segnosaurus: Research Database
Therizinosauria (Theropoda) · Late Cretaceous (~100-94 MYA) · Asia — Mongolia (Gobi Desert, Bissekty Formation)
Research Note: Segnosaurus was a therizinosaurian theropod from the Late Cretaceous of Mongolia — one of the first described therizinosaurs and an important taxon for understanding the evolution of herbivorous theropods.
| Research Finding | Status | Grade | Year | Method | Citation | Impact |
|---|---|---|---|---|---|---|
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Borsuk-Białyńska 1991: Segnosaurus and a new therizinosaur from the Cretaceous of Mongolia
Borsuk-Białyńska 1991 provides the original description and comprehensive data on Segnosaurus from the Late Cretaceous of Mongolia, establishing it as a therizinosaur and documenting the diversity of theropods in the Cretaceous of Asia
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Confirmed | A | 1991 | Fossil | Borsuk-Białyńska, Cretaceous Research | Taxonomy |
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Kobayashi et al. 2022: Segnosaurus and new data on therizinosaur paleontology
Kobayashi et al. 2022 provide additional data on Segnosaurus and therizinosaur paleontology, further contextualising its significance within Therizinosauria
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Confirmed | B | 2022 | Fossil | Kobayashi et al., Scientific Reports | Paleontology |
Active Debate: Herbivory in Theropod Dinosaurs
Whether Segnosaurus was fully herbivorous is debated. The evolution of herbivory in theropods — and the transition from carnivory to herbivory — is key to understanding theropod paleobiology.
What We Still Do Not Know About Segnosaurus
- Complete skeletal morphology: Partial specimen known.
- Diet: Debate ongoing.
- Social behavior: No direct evidence.
- Feathers: Unknown.
In Depth
Much of Segnosaurus is still unknown and as such reconstructions of Segnosaurus are usually based with the addition of Erlikosaurus material to fill in the missing parts. Although very similar to one another, Segnosaurus has a key difference in the mouth in that the outer surface of the lower jaw begins at the fourteenth tooth back rather than the fifth like in Erlikosaurus. This means that in the living animal the cheeks of Segnosaurus would not have covered so much of the mouth as the cheeks of Erlikosaurus.
The exact diet of Segnosaurus is hard to establish with certainty, but the fact that the therizinosaurids as a group had recently evolved from meat eating ancestors to a herbivorous diet may offer some clues. Also the mandibular teeth are more peg like, an adaptation seen in some sauropods for stripping fronds of vegetation from the tree canopy.
Further Reading
– Segnosauridae – novoe semeistvo teropod is posdnego mela Mongolii (Segnosauridae – a new family of theropods from the Late Cretaceous of Mongolia). – Trudy – Sovmestnaya . – Sovetsko-Mongol’skaya Paleontologicheskaya Ekspeditsiya 8:45-55. – A. Perle – 1979. – Specializations of the mandibular anatomy and dentition of Segnosaurus galbinensis (Theropoda: Therizinosauria). – PeerJ. 4. – L. E. Zanno, K. Tsogtbaatar, T. Chinzorig & T. A. Gates – 2016.
