Egg type

Spheroolithus

Zhao 1979

Spheroolithus is an egg type: the name is for the fossil eggs themselves. The animal that laid them is not known for certain. Its eggs are found in rocks 121.4–66 million years old in 7 countries, most often China and the United States.

Confidence labels

VisibleOn tapHidden

How sure are we?0 high19 medium12 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

121.4–66 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: Zhao 1979
medium
medium: Only PBDB gives this; nothing contradicts it.
Sources
Given by: Paleobiology Database. How it was chosen: PBDB leads.
Described in: Z. Zhao (1979). [Advances in the study of fossil dinosaur eggs in our country]. Mesozoic and Cenozoic red beds of South China; selected papers from the field conference on the South China Cretaceous-Early Tertiary red beds. Science Press, Beijing: 330–340.
medium
medium: Only PBDB gives this; its author and year match the naming authority (Zhao 1979).
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.
Dated to: Aptian to Maastrichtian, 121.4–66 million years ago
medium
medium: Only PBDB gives this; nothing contradicts it.
Omnisaura calculation121.4–66 million years ago, from its dated fossil records
medium
medium: Omnisaura's calculation from 34 confirmed PBDB records.
Sources
Given by: Paleobiology Database. How it was chosen: PBDB leads.
Found in: Canada
medium
medium: Only PBDB records it (5 records).
China
medium
medium: Only PBDB records it (9 records).
Mexico
medium
medium: Only PBDB records it (4 records).
Mongolia
medium
medium: Only PBDB records it (4 records).
United States
medium
medium: Only PBDB records it (10 records).
Japan
low
low: Only one PBDB record.
Spain
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: Union of all sources (ISO 3166).
Rock formations: 18, including Cedar Mountain, El Gallo, Oldman and Two Medicine
mixed
mixed: Levels differ between entries; each has its own.
Show all 18, each with its confidence
Baruungoyot
medium
medium: Only PBDB records it (2 records).
Cedar Mountain
medium
medium: Only PBDB records it (3 records).
Dinosaur Park
medium
medium: Only PBDB records it (2 records).
El Gallo
medium
medium: Only PBDB records it (3 records).
Jiangjunding
medium
medium: Only PBDB records it (2 records).
Oldman
medium
medium: Only PBDB records it (3 records).
Quantou
medium
medium: Only PBDB records it (2 records).
Two Medicine
medium
medium: Only PBDB records it (6 records).
Cerro del Pueblo
low
low: Only one PBDB record.
Chichengshan
low
low: Only one PBDB record.
Conques
low
low: Only one PBDB record.
Djadokhta
low
low: Only one PBDB record.
Gaogou
low
low: Only one PBDB record.
Jingangkou
low
low: Only one PBDB record.
Nemegt
low
low: Only one PBDB record.
North Horn
low
low: Only one PBDB record.
Ohyamashimo
low
low: Only one PBDB record.
Pingling
low
low: Only one PBDB record.
Sources
Given by: Paleobiology Database. How it was chosen: Canonical names, automatic and editor-approved matches applied.
Egg family: Spheroolithidae
medium
medium: Only PBDB gives this; nothing contradicts it.
Sources
Given by: Paleobiology Database. How it was chosen: PBDB leads.
Parent group: Spheroolithidae
medium
medium: Only PBDB gives this; nothing contradicts it.
Sources
Given by: Paleobiology Database. How it was chosen: PBDB leads.
Known from: Eggs
Sources
Given by: Paleobiology Database (what the name was based on).
Laid by: Not known for certain. Eggs rarely show which animal laid them.

Sources: Omnisaura editorial (Omnisaura editorial content (© Future Sailors, all rights reserved)), 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

The animal that laid them: not known for certain, as for most egg types.
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.
Held back: 4 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): authority (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…?

Did Spheroolithus meet ?

Yes. Both are found, identified to species, in the same rocks of the same age: Dinosaur Park.

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

Found in the same rocks

Genera and other fossil types from the same formations, from rocks of the same age.

Saurornitholestes Richardoestesia Troodon Centrosaurus Tarbosaurus Paronychodon Prismatoolithus Dromaeosaurus Corythosaurus Elongatoolithus Saurolophus Chasmosaurus Continuoolithus Gallimimus Lambeosaurus Protoceratopsand 134 more

Same family

Other genera in Spheroolithidae with a full profile.

Guegoolithus Paraspheroolithus

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