Egg type
Guegoolithus
Guegoolithus 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 139.1–121.4 million years old in Spain.
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- Named by
- Moreno-Azanza et al. 2014
medium
medium: Only PBDB gives this; nothing contradicts it.Sources
Given by: Paleobiology Database. How it was chosen: PBDB leads.
- Described in
- M. Moreno-Azanza, J. I. Canudo, J. M. Gasca (2014). Spheroolithid eggshells in the Lower Cretaceous of Europe. Implications for eggshell evolution in ornithischian dinosaurs. Cretaceous Research 51(1): 75–87. Read it
medium
medium: Only PBDB gives this; its author and year match the naming authority (Moreno-Azanza et al. 2014).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
- Berriasian to Barremian, 139.1–121.4 million years ago
medium
medium: Only PBDB gives this; nothing contradicts it.Omnisaura calculation139.1–121.4 million years ago, from its dated fossil recordsmedium
medium: Omnisaura's calculation from 3 confirmed PBDB records.Sources
Given by: Paleobiology Database. How it was chosen: PBDB leads.
- Found in
- Spain
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
- BlesaEl Castellar
low
low: Only one PBDB record.El Horcajo Unitlow
low: Only one PBDB record.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.
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.
- Resting on one source: 5 facts come from a single source with nothing against them (rated medium): name (PBDB); 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…?
No. Guegoolithus had gone at least 37.8 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.
Found in the same rocks
Genera and other fossil types from the same formations, from rocks of the same age.
Credits
Where this page comes from
- Paleobiology DatabaseCC BY 4.0 · fossil records, ages, classification
- 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