Happy Mothers Day to all of the amazing mothers out there! In honor of mothers, we thought we would take a look back into the fossil record to learn about the dinosaur Maiasaura, which translates to “Good Mother Reptile”. Maiasaura, of the hadrosaurid (duck-billed) genus, was discovered in 1978 by Laurie Trexler on an expedition to
Montana’s Two Medicine Formation and is one of the few dinosaur species to be given a female name. The reason behind this was the dinosaur’s apparent good parenting skills as evident in the fossil record.
In 1978, Marion Branvold made a fascinating discovery: a nest with the remains of eggshells and the fossils of dinosaurs too small to be fully grown and too large to be hatchlings. Eventually, even more eggs were found , leading the area located in western Montana to become known as “Egg Mountain” and were studied extensively by famed paleontologist Jack Horner. Such nesting grounds are now found all over the world. It is common for many reptiles such as turtles to abandon their young after laying their eggs, leaving them to fend for themselves and for a long time it was assumed that d
inosaurs followed suit, which was why the discovery of Maiasaura breeding grounds was so profound.
Studies of these breeding grounds have revealed young Maiasaura lived alongside their parents for years and have suggested that they travel in herds, raising their young in nesting colonies, with nests packed close to one another, almost like a dinosaur maternity ward. The nests usually contained between 30-40 ostrich sized eggs, laid in a spiral or circular pattern. Because the 30 ft long Maiasaura weighed in on the heavy side, sitting on her nest would have crushed the comparatively small eggs. Instead, the nest was covered with rotting vegetation to keep the eggs warm.
Unlike many young, which are born able to walk, fossils evidence of the hatchlings show that their legs were too underdeveloped to walk, and yet their teeth showed signs of wearing, meaning that food had to be brought to them by their parents. It was the first evidence that large dinosaurs fed and raised their young and changed how paleontologists viewed dinosaurs forever, challenging the view that dinosaurs were solitary creatures. Additionally, it was realized that many dinosaurs previously thought to be separate species were in fact only juvenile forms of already discovered mature dinosaurs.
The discovery of the “good mother dinosaur” taught paleontologists that caring for young was not a trait reserved only for mammals, and that these large, sometimes viscous looking creatures were not by definition exclusively solitary creatures. It was a discovery that profoundly changed the way scientists think of and learn about dinosaurs and opened a door to research that is still ongoing today. It just goes to show mothers of all types have been teaching us a lot for quite a long time! HAPPY MOTHERS DAY!
Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. The Age of Dinosaurs. Publications International, LTD. p. 116-117. ISBN 0-7853-0443-6.
Horner, Jack and Gorman, James. (1988). Digging Dinosaurs: The Search that Unraveled the Mystery of Baby Dinosaurs, Workman Publishing Co.
Lehman, T. M., 2001, Late Cretaceous dinosaur provinciality: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, pp. 310–328.
Trexler, D., 2001, Two Medicine Formation, Montana: geology and fauna: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, pp. 298–309.