By: Staff

Updated on: 28/03/2022

The Maiasaura is a primitive duck-billed dinosaur that walked the earth during the Upper Cretaceous Period. These plant-eating reptiles had a considerably large body and would live in inland areas in a limited region of the then North American continent.

Scientific Classification


Quick Facts

Geological Period:Upper Cretaceous Period (mid to late Campanian) – around 76.7 mya
Size (Length):9 meters (30 ft)
Height:2.5 meters (8.2 ft)
Weight:3,000 – 10,000 kg
Average Lifespan:Unknown
Location/Distribution & Habitat:Areas with dense forests and tall vegetation
Climate/Environment:Warm to moderate
Birth Type (Reproduction):Oviparous
Locomotion:Both bipedal and quadruple

History and Discovery


Initially, in 1978, scientist Marion Brandvold discovered a prehistoric reptile’s nest near Choteau in western Montana, along with the remains of eggshells and babies of some new dinosaur species that were too large to be called hatchlings or new-borns. In fact, this was the very first biological evidence of these giant reptiles taking care of their young ones by feeding and raising them.

Very soon, several other eggshell remains were discovered around the region in the rocks with ‘Two Medicine Formation’ (a type of geologic rock formation). Incidentally, the entire area came to be known as the ‘Egg Mountain’.

Maiasaura Dinosaur
Maiasaura Dinosaur Pictures

In 1979, following these incidents, a paleontologist Laurie Trexler unearthed the first skull of the prehistoric Maiasaura. Later, it was described by scientists Jack Horner and Robert Makela. According to the two dinosaur paleontologists, the discovered skull was the holotype of a new species and named it as Maiasaura peeblesorum. The specimen was serialized as ‘YPM PU 22405’ and was stored by the Yale Peabody Museum of Natural History.

Interestingly, the excavations were successful with more than 200 fossilized specimens, belonging to all age groups, being found from the region. These paleontological digs and the related discoveries, especially the excavation of the Maiasura, demanded the attention of the archeological community, eventually leading to the findings of the fossilized skeletons of a few other types of dinosaurs as well. However, the Maiasaura discovered in Choteau was found in a relatively higher layer of the earth than its other counterparts found in the Two Medicine rock formations.

Physical Description

Maiasaura Skeleton

The Maiasauras were large reptilians that grew up to 30 feet. Their beaks were flat and hadrosaurid (duck-billed), juxtaposed with a thick nose, and a tiny, horn-like crest close to their eyes, above the nostrils.

Maiasaura Size

Though, apparently, they lacked any defense against predators, their heavily muscled tail helped in giving hard blows during combat. These creatures were used to walking in both two, as well as, four legs.

Behavior of the Maiasaura Dinosaur

Maiasaura Pictures

Maiasauras dwelled in an inland habitat, and were gregarious creatures, living in huge herds with even up to 10,000 individuals in a single group. Also, the biologists believe that the crest between their nose and eyes was used as a head-butt during male to male competitions in the breeding/mating season.

The Maisaura parents raised their offspring in nesting colonies. The nests were usually made of mud or earth with each nest consisting of around 30-40 eggs in a coiled pattern, with each egg being the size of that of an ostrich. The nesting colonies were packed close together to one another with an average gap of about 23 feet. Interestingly, the parents did not incubate the eggs manually but would place rotting vegetation on them, which would emit heat.


This dinosaur was a herbivore, feasting upon a wide variety of plant matters, which is quite evident from the anatomy of its mouth and the dental structure (teeth).

Maiasaura Skull

Interesting Facts

  • The generic name of the species – Maiasaura peeblesorum – refers to the Greek goddess Maia, which means a “Good Mother”, while the specific name is in honor of the families of John and James Peebles, on whose land the excavations were carried out.
  • Maisauras appeared in the movie The Land Before Time, as well as in most of the episodes of the television series with the same name.

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