About Maiasaura
| Scientific Name (Genus) | Maiasaura |
| Meaning of Name |
Good mother lizard
maia (good mother) [Greek] - saura (lizard) [Greek] |
| Classification | Ornithischia, Ornithopoda (Hadrosauridae, Hadrosaurinae ) |
| Total Length | Approx. 9m |
| Weight | Approx. 2.5 - 3t |
| Diet | Herbivorous (Omnivorous, also eating crustaceans in wood) |
| Period | Late Cretaceous (Campanian) |
| Sub-classification / Species Name |
Maiasaura peeblesorum
* The specific name peeblesorum is dedicated to the Peebles family, the owners of the land where the fossil was discovered. |
| Year of Paper Publication | 1979 |
| Genus Name Publication |
Nest of juveniles provides evidence of family structure among dinosaurs.
Nature. 282. by John R. Horner.; Robert Makela. 1979. |
Characteristics and Morphology of Maiasaura
Maiasaura is an ornithopod that lived in North America during the Late Cretaceous period, named "good mother lizard" after evidence was discovered showing that they raised their young in groups.
One of its characteristics is that its way of walking changed significantly as it grew. When its weight was light, it was mainly bipedal, using only its hind legs, but as it grew larger and its weight exceeded 1 ton, it transitioned to quadrupedal walking, bringing its front legs to the ground.
In the past, Maiasaura was considered a representative "crestless duck-billed dinosaur." However, recent research has revealed that fully mature adult Maiasaura had a vertically raised bony crest on the top of their heads.
Because this crest was formed quite late in their growth, it is thought to have been used for communication among peers or as a visual display to indicate adulthood.
Egg Mountain and Proof of Parenting
The huge communal nesting ground (colony) in Montana where Maiasaura fossils were discovered is called "Egg Mountain." Surprisingly, the bowl-shaped nests were arranged neatly at uniform intervals of about 7 meters. Seven meters is roughly the same length as an adult Maiasaura, indicating that they built their nests at a perfect distance to prevent the parents from crushing the eggs and chicks.
Due to their massive bodies weighing over 2 tons, the parents could not sit directly on the eggs to warm them. Instead, it is speculated that they laid plant leaves and branches in the nest and used the heat of fermentation to incubate the eggs.
The fossils of chicks less than 1 meter long found in the nests had underdeveloped skeletons and could not walk on their own. Nevertheless, the chicks' teeth clearly showed marks (wear) from chewing hard plants. This is considered conclusive evidence that, since the chicks could not go out of the nest to find food, the parents carried food and fed them mouth-to-mouth or by regurgitation.
In birds and others, this refers to the nature of chicks being born in an immature state and unable to survive without feeding and protection from their parents. Maiasaura seems to have been altricial.
Conversely, those that can walk independently soon after birth are called "precocial."
Astonishing Growth Rate and Huge Herds
Analysis of giant bonebeds where thousands of fossils have been found at once reveals that Maiasaura grew at a speed comparable to modern birds and large mammals.
A newly hatched chick was less than 50 centimeters long, but it exceeded 3 meters in length by the end of its first year, and reached a weight of about 1.2 tons in its third year. Such rapid growth supports the theory that they were "endothermic" (warm-blooded).
In addition, they formed huge herds of thousands to ten thousand individuals to protect themselves from carnivorous dinosaurs. However, it is believed that a herd suffering from a severe drought was once engulfed in volcanic ash from a massive eruption and perished all at once. Thanks to this tragic mass death, fossils of various generations of Maiasaura have been discovered, making it possible to analyze their growth process.
Surprising Diet: Did They Also Eat Crustaceans?
Research on fossilized dinosaur feces (coprolites) has revealed the surprising diet of Maiasaura. They didn't just eat plants at random; they selectively ate "decaying wood" that had been softened and broken down by fungi.
What surprised the paleontology community even more was the discovery of a large amount of shell fragments from "crustaceans," such as crabs and shrimp, in the coprolites. To lay as many as 30 to 40 huge eggs in a single breeding season and feed their chicks, they needed a vast amount of calcium and protein. Therefore, it is thought that during the breeding season, they displayed an "omnivorous" nature, crushing the insects and crustaceans hidden in the decaying wood with their powerful jaws to supplement their nutrition.
A Great Discovery from a Coffee Can and Paper Publication
Source: Nest of juveniles provides evidence of family structure among dinosaurs.
Nature. 282.
by John R. Horner.; Robert Makela. 1979.
The discovery of Maiasaura began in the early summer of 1978 when amateur fossil collector Marion Brandvold kept "small bones" she found in a coffee can. When she showed the bones to paleontologist Dr. Jack Horner, he immediately recognized them as "the bones of a baby hadrosaur."
Guided by Brandvold, Dr. Horner and his friend Bob Makela went to the excavation site in Montana, confirmed that it was a bowl-shaped "nest," and discovered the world's first evidence of "dinosaur parenting."
The following year, in 1979, the two described this dinosaur in the scientific journal "Nature" and named it "Maiasaura peeblesorum," which means "good mother" in Greek. This discovery was a historic breakthrough that overturned the previous conventional wisdom of dinosaurs as "huge, cold-blooded reptiles that abandoned their eggs," showing that they had advanced sociality and family bonds like birds.
Maiasaura Stamp and Fossil Gallery
