10 Facts About Maiasaura, the 'Good Mother Dinosaur'

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How Much Do You Know About Maiasaura?

Museum of the Rockies

Immortalized as the "good mother dinosaur," Maiasaura was a typical hadrosaur, or duck-billed dinosaur, of late Cretaceous North America. Discover 10 fascinating Maiasaura facts.

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Maiasaura Is One of the Few Dinosaurs with a Female Name

Wikimedia Commons

You may have noticed that Maiasaura ends with the Greek suffix "-a," rather than the more familiar "-us." That's because this dinosaur was named (by the famous paleontologist Jack Horner) after the female of the species, in honor of its high level of parental care, as detailed in the following slides. (Fittingly enough, the type specimen of Maiasaura was discovered in 1978 by a female fossil hunter, Laurie Trexler, during an expedition to Montana's Two Medicine Formation.)

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Adult Maiasaura Measured up to 30 Feet Long

Maiasaura dinosaur, artwork

Perhaps because of its identification with females, few people appreciate just how big Maiasaura was--adults measured up to 30 feet long from head to tail and weighed about five tons. Maiasaura wasn't the most attractive dinosaur on the face of the planet, either, sporting the typical body plan of a late Cretaceous hadrosaur (small head, squat torso, and thick, inflexible tail) and only the barest hint of a crest on top of its formidable noggin.

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Maiasaura Lived in Enormous Herds

Wikimedia Commons

Maiasaura is one of the few dinosaurs for which we have incontestable evidence of herding behavior--not just a couple of dozen individuals tramping across the Cretaceous plains (as with contemporary titanosaurs), but aggregations of a few thousand adults, juveniles and hatchlings. The most likely explanation for this herding behavior that Maiasaura needed to defend itself against hungry predators--including the contemporaneous, and very crafty, Troodon (see slide #9).

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Maiasaura Females Laid 30 to 40 Eggs at a Time

Wikimedia Commons

Maiasaura is most famous for its parenting behavior--and that behavior started with females, which laid up to 30 or 40 eggs at a time in carefully prepared nests. (We know about these nests thanks to the discovery of "Egg Mountain," an exquisitely preserved Maiasaura breeding ground.) Because female Maiasaura laid and incubated so many eggs, the eggs of this dinosaur were fairly petite by Mesozoic standards, only about the size of those laid by modern ostriches.

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The Eggs of Maiasaura Were Incubated by Rotting Vegetation

Wikimedia Commons

As you can imagine, a five-ton Maiasaura mom couldn't incubate her eggs simply by sitting on them, like an enormous bird. Rather, as far as paleontologists could tell, Maiasaura parents strewed various kinds of vegetation into their nests, which emitted heat as it rotted away in the jungle-like humidity of late Cretaceous North America. Presumably, this energy source kept the soon-to-be-born Maiasaura hatchlings toasty and warm, and may also have been a convenient source of food after they burst out of their eggs!

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Maiasaura Parents Didn't Abandon Their Young After they Hatched

Alain Beneteau

Paleontologists tend to dismiss the child-care capabilities of dinosaurs, the default assumption being that most dinosaurs abandoned their eggs before, or shortly after, they hatched (much like modern marine turtles). However, the fossil evidence shows that Maiasaura hatchlings and juveniles continued to live alongside their parents for years, and presumably stayed with the herd well into adulthood (at which point they added to it with their own set of hatchlings).

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Maiasaura Hatchlings Grew Over Three Feet in Their First Year of Life

Dinosaur eggs on the rock
swisoot / Getty Images

How long did it take for a newborn Maiasaura to attain its full adult size? Well, judging by analyses of this dinosaur's bones, not as long as you might think: in their first year of life, Maiasaura hatchlings stretched out by over three feet, a phenomenal rate of growth that makes some paleontologists wonder if this dinosaur was ​warm-blooded. (We know that meat-eating dinosaurs had endothermic metabolisms, but the evidence is less clear for ornithopods like Maiasaura.)

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Maiasaura May Have Been Preyed on by Troodon

Figure of Troodon
Figure of Troodon. Srdjan Stefanovic / Getty Images

During the late Cretaceous period, Maiasaura lived in a fairly complex ecosystem, sharing its territory not only with other hadrosaurs (such as Gryposaurus and Hypacrosaurus) but also meat-eating dinosaurs like Troodon and Bambiraptor. This latter dinosaur was way too small to inflict much damage on a Maiasaura herd, but the 150-pound Troodon might have been able to cull out elderly or sick individuals, especially if it hunted its duck-billed prey in packs.

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Maiasaura Was a Close Relative of Brachylophosaurus

Brachylophosaurus with offspring.
Brachylophosaurus with offspring. Stocktrek Images / Getty Images

A huge number of hadrosaurs, or duck-billed dinosaurs, ranged across the expanse of late Cretaceous North America. Technically, Maiasaura is classified as a "saurolophine" hadrosaur (meaning it was descended from the slightly earlier Saurolophus), and its closest relative was Brachylophosaurus, which has been memorialized, rightly or wrongly, as the "dinosaur mummy." To date, there is only one identified species of Maiasaura, M. peeblesorum.

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Maiasaura Was an Occasional Biped

Dinosaurs at a watering hole, illustration

Part of what made hadrosaurs like Maiasaura so ungainly looking was their means of locomotion. Ordinarily, they crouched low to the ground, on all fours, happily munching vegetation--but when they were startled by predators, they were capable of running away on their two hind legs, which would have been a comical sight if there weren't so much at stake, evolutionarily speaking. (And we won't even speculate about the damage that could be inflicted on the landscape by a stampeding herd of Maiasaura!)

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Strauss, Bob. "10 Facts About Maiasaura, the 'Good Mother Dinosaur'." ThoughtCo, Feb. 16, 2021, thoughtco.com/things-to-know-maiasaura-1093792. Strauss, Bob. (2021, February 16). 10 Facts About Maiasaura, the 'Good Mother Dinosaur'. Retrieved from https://www.thoughtco.com/things-to-know-maiasaura-1093792 Strauss, Bob. "10 Facts About Maiasaura, the 'Good Mother Dinosaur'." ThoughtCo. https://www.thoughtco.com/things-to-know-maiasaura-1093792 (accessed May 29, 2023).