COMPLETE MOUNTED DUCK-BILLED DINOSAUR SKELETON. ...

 

COMPLETE MOUNTED DUCK-BILLED DINOSAUR SKELETON
Maiasaura peeblesorum
Upper Cretaceous
Two Medicine Formation, northwestern Montana
The Maiasaura was one of the last dinosaurs ever to walk the Earth; a member of the duck-billed Hadrosauridae family, it was a classic North American herbivore. Their name comes from the Greek "mother lizard" because it is believed that they nurtured their young for a significantly longer period than other species; a large nesting site discovered in the Two Medicine Formation of northern Montana has proven a treasure trove of behavioral evidence for paleontologists.

Various species of Hadrosaurid roamed the plains of Asia, Europe and North America 99-65 million years ago. Traveling in great herds, they used their flattened beak-like mouths to strip trees of twigs and foliage. Standing on their hind legs to pull at the higher branches with their short, strong forearms or falling to all fours to flee from predators; the Maiasaura was a comparatively swift dinosaur for its size; essential given that it shared its ecosystem with such fearsomely efficient predators as the tyrannosaurid Albertosaurus. An adult Maiasaura could grow up to 30 feet in length, standing 9 feet tall and weighing 3 to 4 tons. They would return annually to their nesting sites, where grapefruit-sized eggs were typically laid in batches of 20 to 25. The mothers would tend to their young until the hatchlings had more or less doubled in size - notably bird-like behavior. Like new-born chicks, very young Maiasaura had legs insufficiently developed to carry them from the nest, but the presence of worn-teeth amongst still nest-bound young indicates that the mother would bring food to the nest for several months following birth, possibly up to as long as one year. It is also apparent that rather than sit over their eggs, the mother Maiasaura would incubate them in rotting vegetation to keep them at an adequately warm temperature. This motherly behavior led to the creature's being the only dinosaur to have been granted a female-form Latin name, coined by paleontologists Robert Makela and Jack Horner (consultant for Jurassic Park) in 1979. The first Maiasaura had been discovered a few years previously by Laurie Trexler, and in 1977 Marion Brandvold and her son David Trexler discovered the enormous bone-bed/nesting ground in Montana which would become known as "Egg Mountain". This location, the largest nesting site in the Western Hemisphere, yielded over 200 individual Maiasaura fossils and approximately 40 nests, spread over a 2½ acre area; its discovery contributed to The Two Medicine Formation's already well-established reputation as one of the most paleontologically significant rock layers in the world. Approximately 83.5 to 70.5 million years ago during the Campanian stage of the Upper Cretaceous, it was deposited between the western shoreline of the Interior Seaway and the advancing eastern margin of the Cordilleran Overthrust Belt, in what is today northwestern Montana. Aside from the abundance of Egg Mountain, the strata has yielded innumerable species of Hadrosaur, Ankylosaur, Ceratopsian, Deinonychosaur, Oviraptosaur, Ornithopods and Tyrannosauroids, making it one of the most important dinosaur-bearing formations in the world.


First discovered in 1992 but not mounted until 2007, the present skeleton is that of a sub-adult Maiasaura, named by the preparators "Cory". It is one of the most complete mounted specimens of the species known, with an especially well-preserved, undistorted skull. Another significant and unusually fine feature is that it was found with incredible natural articulation to the hind legs and tail. Given that it is still a sub-adult, the articulation of the not-yet fused astragalus (or talus - ankle bone) and calcaneum (hock point bone) with the tibia and fibula on both hind legs is outstanding. The tail itself features 36 superbly-preserved caudal vertebrae and overall the skeleton consists of over 80% original bones, the remainder having been incorporated with scrupulous scientific accuracy. The same outstanding care as went into the preparation of this specimen has also been applied to its presentation, using the most up-to-date and non-invasive methods: a bracket mount system was utilized to avoid any drilling or other kind of compromise to the bones, and each individual piece can be easily removed from the armature for close scientific study. An innovative gravity-mount system was used for the feet, whereby individual toe bones fit into slots such that they are held in place by gravity alone and can likewise be individually removed with ease. The mounting of the skull is also unique, allowing it to move freely from side to side and up and down through a range of approximately 30°, and the mandibles can be arranged in either a closed or open-mouthed position. An exceptional specimen, measuring 17 feet in length, prepared and presented to the highest standards possible, it is truly a world-class fossil in every way.

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