Dinosaur genus

Eucoelophysis

Sullivan and Lucas 1999

Eucoelophysis is a dinosaur genus known from bones, found in rocks 227.3–201.4 million years old, in the United States.

Confidence labels

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Confidence labels are switched off. Facts with low confidence, or where sources disagree, still carry a small dot: tap it for the reason.

At a glance

Data as of 11 October 2026

227.3–201.4 Ma

Triassic

Jurassic

Cretaceous

252 million years ago20114366

The last non-bird dinosaurs died out 66 million years ago. That's as far from us as the end of this bar.

Named by: Sullivan and Lucas 1999
medium
medium: Only PBDB gives this; nothing contradicts it.
Sources
Given by: Paleobiology Database. How it was chosen: PBDB leads.
Described in: R. M. Sullivan, S. G. Lucas (1999). Eucoelophysis baldwini, a new theropod dinosaur from the Upper Triassic of New Mexico, and the status of the original types of Coelophysis. Journal of Vertebrate Paleontology 19(1): 81–90. Read it
medium
medium: Only PBDB gives this; its author and year match the naming authority (Sullivan and Lucas 1999).
Sources
Given by: Paleobiology Database. The publication the Paleobiology Database gives as the authority for this genus name, usually the one that first named and described it.
Lived: Norian to Rhaetian, 227.3–201.4 million years ago
medium
medium: Only PBDB gives this; nothing contradicts it.
Omnisaura calculation227.3–201.4 million years ago, from its dated fossil records
low
low: Omnisaura's calculation from only 2 dated record(s).
Sources
Given by: Paleobiology Database. How it was chosen: PBDB leads.
Fossils found in: United States
medium
medium: Only PBDB records it (2 records).
Sources
Given by: Paleobiology Database. How it was chosen: Union of all sources (ISO 3166).
Rock formations: Chinle
medium
medium: Only PBDB records it (2 records).
Sources
Given by: Paleobiology Database. How it was chosen: Canonical names, automatic and editor-approved matches applied.
Family: Silesauridae
medium
medium: Only PBDB gives this; nothing contradicts it.
Sources
Given by: Paleobiology Database. How it was chosen: PBDB leads.
Parent group: Sulcimentisauria
medium
medium: Only PBDB gives this; nothing contradicts it.
Sources
Given by: Paleobiology Database. How it was chosen: PBDB leads.
Species named in its records: Eucoelophysis baldwini
Sources
Given by: Paleobiology Database (the species its fossil records are identified as).
Diet: herbivore (inferred for its group)
medium
medium: Only PBDB gives this, and it infers it for the whole of Ornithischia, the group this genus belongs to, not from this genus's own fossils.
Sources
Given by: Paleobiology Database. How it was chosen: PBDB, inferred from a group the genus belongs to.
Way of life: ground dwelling, gregarious (inferred for its group)
low
low: PBDB infers this way of life for the whole of Ornithischia; behaviour is rarely known for one genus.
Sources
Given by: Paleobiology Database. How it was chosen: PBDB, inferred from a group the genus belongs to.
Known from: Bones
Sources
Given by: Paleobiology Database (what the name was based on).

Sources: Paleobiology Database (CC BY 4.0), Wikidata (CC0 1.0)Confidence levels and gaps are Omnisaura's own assessment.

Gaps are answers

What isn't known yet

Type species: no source we use gives it yet.
Order: no source we use gives it yet.
Common names: no source we use gives it yet.
What it was named after: no source we use gives it yet.
Resting on one source: 5 facts come from a single source with nothing against them (rated medium): authority (PBDB); parent group (PBDB); family (PBDB); age (headline) (PBDB); diet (PBDB).

Size and appearance aren't covered yet, and diet and way of life only as PBDB infers them for the wider group. Omnisaura leaves the rest out rather than guess.

Where sources disagree

None open. Where our sources overlap, they agree on everything shown here.

Did it meet…?

Did Eucoelophysis meet ?

No. Eucoelophysis had gone at least 117.8 million years before Tyrannosaurus appears in the fossil record, a longer gap than the 66 million years between Tyrannosaurus and today.

Going by the ages and rock formations of their dated fossils, as on the map. Compare their fossil sites on the map.

Connections

Genera linked to Eucoelophysis by where and when their fossils were found, by classification and by who named them. Select a name to open its page.

Same rocks, same time 12

Genera found in the same rock units, from rocks of overlapping age, the most shared fossil sites first.

Coelophysis Grallator Krzyzanowskisaurus Kwanasaurus Barrancapus Camposaurus Chindesaurus Daemonosaurus Eosauropus Eubrontes Pseudotetrasauropus Tawa

Same family: Silesauridae 5

Other genera in Silesauridae with a full profile.

Amanasaurus Asilisaurus Kwanasaurus Lewisuchus Silesaurus

Named by Lucas and Sullivan 8

Genera whose naming authority includes the same surname. The authority has no initials, so different people who share a surname can appear together.

Agujaceratops Ahshislepelta Alaskacephale Anasazisaurus Colepiocephale Dacentrurus Hoplitosaurus Nodocephalosaurus

Found in United States 25

Other genera found in United States, from rocks of overlapping age, the most fossil sites there first.

Grallator Eubrontes Eosauropus Coelophysis Anchisauripus Evazoum Anomoepus Atreipus Kayentapus Pseudotetrasauropus Barrancapus Coelurosaurichnus Dilophosauripus Gregaripus Krzyzanowskisaurus Kwanasaurusand 9 more

Credits

Where this page comes from

Paleobiology DatabaseCC BY 4.0 · fossil records, ages, classification
WikidataCC0 1.0 · names and identifiers
OmnisauraOmnisaura editorial · confidence levels and gaps
PaleoMAP PaleoCoastlines (Kocsis and Scotese 2021)CC BY 4.0 · ancient coastlines on the small map
Natural EarthPublic domain · today's coastlines