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Dinosaur genus

Tenontosaurus

Ostrom 1970

Tenontosaurus is a dinosaur genus known from bones, found in rocks 121.4–93.9 million years old, in the United States.

Confidence labels
How sure are we?0 high10 medium5 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
121.4–93.9 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
Ostrom 1970
mediummedium: Only PBDB gives this; nothing contradicts it.
Sources

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

Described in
J. H. Ostrom (1970). Stratigraphy and paleontology of the Cloverly Formation (Lower Cretaceous) of the Bighorn Basin area, Wyoming and Montana. Peabody Museum Bulletin 35: 1–234.
mediummedium: Only PBDB gives this; its author and year match the naming authority (Ostrom 1970).
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.

Type species
Tenontosaurus tilletti
mediummedium: Only PBDB gives this; nothing contradicts it.
Sources

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

Lived
Aptian to Cenomanian, 121.4–93.9 million years ago
mediummedium: Only PBDB gives this; nothing contradicts it.
Omnisaura calculation121.4–93.9 million years ago, from its dated fossil records
mediummedium: Omnisaura's calculation from 70 confirmed PBDB records.
Sources

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

Fossils found in
United States
mediummedium: Only PBDB records it (70 records).
Sources

Given by: Paleobiology Database. How it was chosen: Union of all sources (ISO 3166).

Rock formations
Antlers
mediummedium: Only PBDB records it (7 records).
Cloverly Formation
mediummedium: Only PBDB records it (58 records).
Arundel Clay
lowlow: Only one PBDB record.
Paluxy
lowlow: Only one PBDB record.
Shellenberger Canyon
lowlow: Only one PBDB record.
Twin Mountains
lowlow: Only one PBDB record.
Wayan
lowlow: Only one PBDB record.
mixedmixed: Levels differ between entries; each has its own.
Sources

Given by: Paleobiology Database. How it was chosen: Canonical names, automatic and editor-approved matches applied.

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

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

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

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

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

  • 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.
  • Held back: 13 fossil records left out: identified only tentatively (for example "cf." or "?").
  • Resting on one source: 5 facts come from a single source with nothing against them (rated medium): authority (PBDB); type species (PBDB); parent group (PBDB); family (PBDB); age (headline) (PBDB).

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…?

?

No. Tenontosaurus had gone at least 10.3 million years before Tyrannosaurus appears in the fossil record.

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.

DeinonychusSauropeltaAcrocanthosaurusMicrovenatorOryctodromeusSauroposeidonAquilopsAstrophocaudiaBrontopodusCedarosaurusCoelurusConvolosaurusMacroelongatoolithusZephyrosaurus

Same family

Other genera in Tenontosauridae with a full profile.

Convolosaurus

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.