ar·cho·saur
ˈär-kə-ˌsȯr 
: any of a subclass (Archosauria) of reptiles comprising the dinosaurs, pterosaurs, and crocodilians
Ar·cho·sau·ria
ˌär-kə-ˈsȯr-ē-ə
: a large subclass of Reptilia comprising the dinosaurs, pterosaurs, and crocodilians all distinguished by possessing temporal openings separated from each other by a postorbitosquamosal arch
Examples of archosaur in a Sentence
Recent Examples on the Web
CBS News, 16 Dec. 2025
The discovery came with the find of Ixalerpeton, a small lagerpetid archosaur and a close relative of pterosaurs, unearthed from 233-million-year-old rocks in Brazil.
—Mrigakshi Dixit, Interesting Engineering, 27 Nov. 2025
The discovery immediately sparked debate over the evolutionary pathways of miniaturization and morphological convergence, challenging assumptions about how small archosaurs could become and how to interpret highly specialized skull forms in the fossil record.
—Scott Travers, Forbes.com, 29 Apr. 2025
During the Triassic, a broad group known as the archosaurs evolved and eventually split into two major lineages.
—Sean Mowbray, Discover Magazine, 1 Aug. 2024
Birds and crocodilians are archosaurs, the living relatives of non-avian dinosaurs and pterosaurs.
—Jeanne Timmons, Ars Technica, 26 July 2023
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Noun
There may also be tracks of predatory dinosaurs and archosaurs, the ancestors of crocodiles, the press release said.
—CBS News, 16 Dec. 2025
The discovery came with the find of Ixalerpeton, a small lagerpetid archosaur and a close relative of pterosaurs, unearthed from 233-million-year-old rocks in Brazil.
—Mrigakshi Dixit, Interesting Engineering, 27 Nov. 2025
The discovery immediately sparked debate over the evolutionary pathways of miniaturization and morphological convergence, challenging assumptions about how small archosaurs could become and how to interpret highly specialized skull forms in the fossil record.
—Scott Travers, Forbes.com, 29 Apr. 2025
During the Triassic, a broad group known as the archosaurs evolved and eventually split into two major lineages.
—Sean Mowbray, Discover Magazine, 1 Aug. 2024
Birds and crocodilians are archosaurs, the living relatives of non-avian dinosaurs and pterosaurs.
—Jeanne Timmons, Ars Technica, 26 July 2023
Cite this Entry
“Archosaur.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/archosaur. Accessed 23 Jun. 2026.
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