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Diggin' For Dinosaurs - Museum Of Northern Arizona
Museum of Northern Arizona, AZ
The Colorado Plateau rises like a great block of stone in the Four Corners region of the Southwest. The plateau is composed of sedimentary layers deposited and compressed into solid rock over hundreds of millions of years and then heaved straight up by the collision of continental plates. Water and wind have sculpted the rock into a dreamscape of canyons, mesas, spires, and arches, and exposed the plateau's geologic history. Within 75 miles of Flagstaff, Arizona, visible rocks date from a thousand to 1.7 billion years old; no place on Earth presents a more accessible and vast span of geologic time.
This arid land, where vegetation scarcely obscures the cliffs and flats, also bares its bones. Fossils found in the plateau's sedimentary storehouse have given palaeontologists an excellent idea of what grew, swam, and walked here. And important portions of that record are preserved and displayed at the Museum of Northern Arizona, whose researchers have played a primary role in illuminating the region's ancient past.
A tour of the museum's geology gallery begins, figuratively speaking, before creatures walked on land. In the depths of the Grand Canyon, rocks 1.2 billion years old bear impressions of stromatolites, microbial communities that to this day form moundlike structures in warm, saline waters. In the past, they lived in shallow marine environments, giving off oxygen that helped create the modern atmosphere before other life-forms evolved.
The exhibits then follow the march of evolution through the rock strata of the Grand Canyon, starting with trilobites and brachiopods, club mosses and conifers, scorpion and reptile tracks, and finally a large shark tooth from the white Kaibab limestone at the rim of the canyon.
You'll find a fair collection of dinosaur fossils, too. A few are regional specialties, such as a mounted reconstruction of a Dilophosaurus skeleton 10 feet high and 12 feet long. Found only in northern Arizona, this imposing, early Jurassic predator sports two long bony crests atop its skull. Another local is Scuttelosaurus, a small herbivore whose skeleton was found in the Painted Desert northeast of Flagstaff. Heavily armored with bony scales, it could run on two legs but probably preferred to walk on four. Two skulls depict the early dinosaur Coelophysis, which has been found at several sites in the region.
More recent dinosaur fossils come from other parts of the Colorado Plateau, most notably upper Cretaceous deposits in the San Juan Basin of northwest New Mexico. The most striking is the five-foot-long femur of a duckbilled dinosaur, a huge herbivore that probably used its wide-flanged lower jaw to strain vegetation from ponds and streams as dabbling ducks do today. Beside it are relics of other giants: the two-foot-long jaw of a ceratopsian and the three-inch-long, serrated tooth of a tyrannosaur.
The age of large beasts did not end with dinosaurs. Fossil bones and teeth of Pleistocene ground sloths, mammoths, and mastodons reveal that animals far larger than today's lived here even after humans arrived. Nearby, the museum's other galleries show how people both ancient and modern have reacted to the stark and scenic landscapes of the Colorado Plateau.