Maiasaura

Name: Maiasaura ‭(‬Caring/Good mother lizard‭)‬. Phonetic: My-ah-sore-ah. Named By: Jack Horner‭ & ‬Robert Makela‭ ‬-‭ ‬1979. Classification: Chordata,‭ ‬Reptilia,‭ ‬Dinosauria,‭ ‬Ornithischia,‭ ‬Ornithopoda,‭ ‬Hadrosauridae,‭ ‬Saurolophinae,‭ ‬Brachylophosaurini. Species: M.‭ ‬peeblesorum‭ (‬type‭)‬. Diet: Herbivore. Size: Around‭ ‬9‭ ‬meters long. Known locations: USA‭ ‬-‭ ‬Montana‭ ‬-‭ ‬Two Medicine Formation. Time period: Late Campanian of the Cretaceous. Fossil representation: Remains of over‭ ‬200‭ ‬individuals from newly hatched juveniles to adults including nests.

At up to nine meters long Maiasaura was not amongst the largest known hadrosaurid dinosaurs,‭ ‬though it still tipped the scale to be considered big for its kind.‭ ‬Like with its hadrosaurid relatives,‭ ‬Maiasaura is thought to have been a primarily bipedal dinosaur,‭ ‬though one that was at least capable of balancing if not walking upon just its hind legs.‭ ‬The exact posture assumed was probably more dependent upon what the Maiasaura in question was actually doing at the time.‭ ‬Maiasaura had a low crest on top of it snout and because it is solid,‭ ‬this indicates that Maiasaura was one of the saurolophine hadrosaurs. Maiasaura might appear to be a rather plain looking hadrosaurid,‭ ‬but its real importance is not about its looks but upon the remains of nests that members of this genus created.‭ ‬One of the most significant fossil sites associated with Maiasaura is an area that we know today as‭ ‘‬Egg Mountain‭’‬.‭ ‬Here a concentration of nests spread apart at distances of around seven meters from each other,‭ ‬each containing around thirty to forty eggs about fifteen centimetres across were found with multiple remains of Maiasaura scattered around them.‭ ‬Some of these remains were of juveniles too large to have just hatched with underdeveloped rear legs.‭ ‬The skulls of juveniles also have very different proportions to those of the adults,‭ ‬though this is quite common in vertebrates.‭ ‬In addition to these were remains of adult Maiasaura,‭ ‬something that suggests that adults would not just lay their eggs and wander off,‭ ‬but stay close to the nests and their young for some time.‭ ‬Bearing in mind the underdeveloped rear eggs of the younger juveniles it’s possible that a more precise scenario is that the adult Maiasaura would move away from the nests for short periods while they foraged to bring food back to the nest while‭ ‬the hatchlings became strong enough to walk around and forage for themselves. The sheer number of nests and Maiasaura fossils from the Egg Mountain site is proof that Maiasaura would congregate in large numbers during the nesting‭ ‬period,‭ ‬however it remains impossible to say‭ ‬for‭ ‬certain how this genus lived when not nesting.‭ ‬It’s not impossible that when Maiasaura were not nesting they moved around in much smaller groups to reduce the impact on the ecosystem in a given area,‭ ‬more mouths in one place would after all cause more destruction to the plants growing there,‭ ‬increasing the amount of time necessary for the ecosystem to recover,‭ ‬although hadrosaurids like Maiasaura might have been continually on the move and only staying put for short periods such as nesting.‭