Dinosaur genus
Sphaerotholus
Sphaerotholus is a dinosaur genus known from bones, found in rocks 83.6–66 million years old, in the United States and Canada.
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- Named by
- Williamson and Carr 2003
medium
medium: Only PBDB gives this; nothing contradicts it.Sources
Given by: Paleobiology Database. How it was chosen: PBDB leads.
- Described in
- T. E. Williamson, T. D. Carr (2003). A new genus of derived pachycephalosaurian from western North America. Journal of Vertebrate Paleontology 22(4): 779–801. Read it
medium
medium: Only PBDB gives this; its author and year match the naming authority (Williamson and Carr 2003).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
- Sphaerotholus goodwini
medium
medium: Only PBDB gives this; nothing contradicts it.Sources
Given by: Paleobiology Database. How it was chosen: PBDB leads.
- Lived
- Campanian to Maastrichtian, 83.6–66 million years ago
medium
medium: Only PBDB gives this; nothing contradicts it.Omnisaura calculation83.6–66 million years ago, from its dated fossil recordsmedium
medium: Omnisaura's calculation from 5 confirmed PBDB records.Sources
Given by: Paleobiology Database. How it was chosen: PBDB leads.
- Fossils found in
- CanadaUnited States
medium
medium: Only PBDB records it (2 records).medium
medium: Only PBDB records it (3 records).Sources
Given by: Paleobiology Database. How it was chosen: Union of all sources (ISO 3166).
- Rock formations
- Hell Creek FormationDinosaur Park
medium
medium: Only PBDB records it (2 records).Kirtlandlow
low: Only one PBDB record.low
low: Only one PBDB record.mixed
mixed: 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
- Pachycephalosauridae
medium
medium: Only PBDB gives this; nothing contradicts it.Sources
Given by: Paleobiology Database. How it was chosen: PBDB leads.
- Parent group
- Pachycephalosaurinae
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
- Sphaerotholus buchholtzae, Sphaerotholus goodwini, Sphaerotholus lyonsi, Sphaerotholus triregnum
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).
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: 1 fossil record left out: identified only tentatively (for example "cf.", "?" or the name in quotation marks).
- Resting on one source: 7 facts come from a single source with nothing against them (rated medium): name (PBDB); authority (PBDB); type species (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…?
Yes. Both are found, identified to species, in the same rocks of the same age: Dinosaur Park, Hell Creek, Kirtland.
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 Sphaerotholus 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 69
Genera found in the same rock units, from rocks of overlapping age, the most shared fossil sites first.
Same family: Pachycephalosauridae 6
Other genera in Pachycephalosauridae with a full profile.
Named by Carr and Williamson 3
Genera whose naming authority includes the same surname. The authority has no initials, so different people who share a surname can appear together.
Found in United States 105
Other genera found in United States, from rocks of overlapping age, the most fossil sites there first.
Credits
Where this page comes from
- Paleobiology DatabaseCC BY 4.0 · fossil records, ages, classification
- Natural History Museum Data PortalCC0 1.0 · catalogued specimens
- 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