Omnisaura
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Dinosaur genus

Thescelosaurus

Gilmore 1913

Thescelosaurus is a dinosaur genus known from bones, found in rocks 83.6–66 million years old, in the United States and Canada.

Also calledzh 奇異龍
mediummedium: Only Wikidata gives this; nothing contradicts it.
Confidence labels
How sure are we?5 high9 medium1 lowHow we rate confidence

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 12 October 2026
83.6–66 Ma
Triassic
Jurassic
Cretaceous
252 million years ago20114366

Solid: the ages of its dated fossils, 83.6–66 million years ago (Omnisaura's calculation). Pale: the published range, 93.9–66 million years ago, which also counts records Omnisaura leaves out.

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
Gilmore 1913
highhigh: PBDB and Wikidata agree.
Sources

Given by: Paleobiology Database. How it was chosen: PBDB leads.

Described in
C. W. Gilmore (1913). A new dinosaur from the Lance Formation of Wyoming. Smithsonian Miscellaneous Publications 61(5): 1–5.
highhigh: PBDB gives this publication for the name; its author and year match the naming authority (Gilmore 1913), on which PBDB and Wikidata agree.
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
Turonian to Maastrichtian, 93.9–66 million years ago
highhigh: PBDB and NHM agree.
Omnisaura calculation83.6–66 million years ago, from its dated fossil records
mediummedium: Omnisaura's calculation from 42 confirmed PBDB records.
Sources

Given by: Paleobiology Database. How it was chosen: PBDB leads.

Fossils found in
United States
highhigh: NHM and PBDB both record it.
Canada
mediummedium: Only PBDB records it (5 records).
mixedmixed: Levels differ between entries; each has its own.
Sources

Given by: Paleobiology Database; Natural History Museum Data Portal. How it was chosen: Union of all sources (ISO 3166).

Rock formations
Lance Formation
highhigh: NHM and PBDB both record it.
Frenchman
mediummedium: Only PBDB records it (2 records).
Hell Creek Formation
mediummedium: Only PBDB records it (27 records).
Scollard
mediummedium: Only PBDB records it (2 records).
Laramie Formation
lowlow: Only one PBDB record.
mixedmixed: Levels differ between entries; each has its own.
Sources

Given by: Paleobiology Database; Natural History Museum Data Portal. How it was chosen: Canonical names, automatic and editor-approved matches applied.

Family
Thescelosauridae
mediummedium: Only PBDB gives this; nothing contradicts it.
Sources

Given by: Paleobiology Database. How it was chosen: PBDB leads.

Parent group
Thescelosaurinae
mediummedium: Only PBDB gives this; nothing contradicts it.
Sources

Given by: Paleobiology Database. How it was chosen: PBDB leads.

Order
Ornithischia
mediummedium: Only NHM gives this; nothing contradicts it.
Sources

Given by: Natural History Museum Data Portal. How it was chosen: Gap filled from NHM.

Known from
Bones
Sources

Given by: Paleobiology Database (what the name was based on).

Sources: Paleobiology Database (CC BY 4.0), Natural History Museum Data Portal (CC0 1.0), 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.
  • What it was named after: no source we use gives it yet.
  • Held back: 13 fossil records left out: identified only tentatively (for example "cf." or "?").
  • Resting on one source: 4 facts come from a single source with nothing against them (rated medium): parent group (PBDB); family (PBDB); order (NHM); common names (Wikidata).

Size, diet and behaviour aren't covered yet. Omnisaura leaves them out rather than guess.

Where sources disagree

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

Did it meet…?

?

Yes. Both are found, identified to species, in the same rocks of the same age: Frenchman, Hell Creek, Lance, Scollard.

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

Lived alongside

Genera found in the same rock formations, from rocks of the same age.

TriceratopsEdmontosaurusTyrannosaurusParonychodonRichardoestesiaPachycephalosaurusChirostenotesOrnithomimusTroodonAnkylosaurusSaurornitholestesLeptoceratopsNanotyrannusPectinodonTorosaurusTrierarchuncusand 18 more

Same family

Other genera in Thescelosauridae with a full profile.

AlbertadromeusChangchunsaurusChangmianiaFonaHayaJeholosaurusKoreanosaurusOrodromeusOryctodromeusParksosaurusZephyrosaurus

Credits

Where this page comes from

  • Paleobiology DatabaseCC BY 4.0 · fossil records, ages, classification
  • Natural History Museum Data PortalCC0 1.0 · catalogued specimens
  • 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

Pictures linked from this page are credited beside each one, with their own licences; the full list is in the JSON download.