Cretaceous
Maiasaura
Maiasaura peeblesorum
The catalogue presents Maiasaura as a herbivore member of Hadrosauridae that lived during the Cretaceous, between 76.7–75.0 Ma. Its estimated range is 9.0 m in length and 3.0–4.0 t in mass, giving a practical sense of scale. Reference material comes from Two Medicine Formation, Montana, USA. Size and mass are approximations and may change with new fossils or methods.
Evidence-backed summary
For Maiasaura, the PBDB records the taxonomic attribution as Horner and Makela (1979).
The PBDB places it in Brachylophosaurini, and the catalogue record assigns it to the family Hadrosauridae.
- PBDB · taxon.parent
- Hadrosauridae
In the PBDB record, the reported stratigraphic range is the Campanian.
The PBDB catalogues 5 occurrences, with material from the Two Medicine Formation (5). Provenance: United States.
The catalogue records the holotype as YPM-PU 22405 and the type locality as “Two Medicine Formation, Montana, USA”.
- YPM-PU 22405
- Two Medicine Formation, Montana, USA
The catalogue's reference measurements are 9.0 m in length and 3.0–4.0 t in mass — estimates, which vary with specimen and method.
- 9.0 m
- 3.0-4.0 tons
The record gathers 37 bibliographic references registered in the PBDB, listed below.
Where it lived
Fossil occurrences on today’s map and in the tectonic reconstruction.
Positions reconstructed by PBDB/GPlates, not observed; this is not an exact habitat map.
Artistic 3D reconstruction
There is no approved species-specific 3D model yet. Generic anatomy will not be presented as if it were evidence.
Physical Specifications
- Length
- 9.0 m
- Weight
- 3.0–4.0 t
- Period
- Cretaceous
- Time range
- 76.7–75.0 Ma
Discovery Information
- First Discovery
- 1979
- Described by
- Jack Horner
Taxonomic Classification
- Kingdom
- Animalia
- Phylum
- Chordata
- Class
- Reptilia
- Order
- Ornithischia
- Family
- Hadrosauridae
- Genus
- Maiasaura
- Species
- M. peeblesorum
Data status
Taxonomic name matched to PBDB and checked on 2026-08-08.
Taxonomic linkage does not automatically validate size, mass, behaviour or appearance.
- Type specimen
- YPM-PU 22405
- Type locality
- Two Medicine Formation, Montana, USA