Giant flightless bird — Diatryma gigantea

Geologic period: Early Eocene — Wasatchian

Age: Early Eocene.

Taxonomic note: Diatryma was often synonymized with Gastornis, but a 2024 gastornithiform review resurrected Diatryma. SAGE therefore retains the Smithsonian genus instead of silently rewriting it to Gastornis.

Feeding: Diet remains scientifically debated; do not label it a predatory 'terror bird' as established fact.

Evidence: Large limb bones and other gastornithiform fossils directly document its enormous size. Diet has been debated and should not be turned into a dramatic predator story without evidence.

Why it matters: Diatryma shows how quickly large-bodied birds occupied terrestrial ecosystems after the end-Cretaceous extinction.

Plain Language Identity: A giant flightless gastornithiform bird from the Early Eocene.

What You Are Looking At: A composite cast representing the giant bird Diatryma gigantea.

Ecosystem: Early Eocene terrestrial environment of North America.

Source Urls: https://naturalhistory.si.edu/visit/virtual-tour/current-exhibits/deep-time-virtual-tour-fossil-list; https://www.si.edu/object/diatryma-gigantea-cope:nmnhpaleobiology_3368497; https://www.palaeo-electronica.org/content/2024/5393-review-of-gastornithiformes

Find Location: New Mexico, United States for the holotype material.

Enrichment Method: SAGE curated research pass; title + scientific name + source scene matched; chronology and taxonomy conflicts retained rather than silently corrected; evidence separated from inference

Scientific name: Diatryma gigantea

Evidence / representation: Representative evidence-type visual; not the exact specimen.

Representative evidence-type visual; not the exact specimen.

After the Dinosaurs: Mammals, Ice Ages and the World We Inherited.