Top Ten Parks for Fossils and Dinosaurs

Where Ancient times preserved in the natural archives of our planet
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McKee Springs Petroglyphs, Dinosaur national Monument
McKee Springs Petroglyphs, Dinosaur national Monument  (National Park Service)

Centuries ago, people in China found huge bones exposed on the ground and decided they were the skeletons of dragons. We know them as dinosaurs. Their fossil remains are found on every continent, along with gangly proto-birds, tiny rodents, horses, fish, flowers, ferns, insects, tree trunks—even algae.

Dinosaur National Monument: Spectacular Quarry of Fossil Bones
We start with the big ones. The supposed dragons. They lived from about 245 million years ago until 65 million years ago, when a natural catastrophe— evidence supports that a huge meteorite hit Earth—caused their extinction. Dinosaurs, of course, existed in a huge variety of sizes and shapes; however, it's the big ones that stir our imaginations. This Colorado monument is best known for its spectacular quarry, a steeply angled rock wall that displays a dense concentration of partially excavated fossil bones. The bones are in the Morrison formation, a mix of sandstone and conglomerate deposited during the Jurassic period 150 million years ago. The concentration here is thought to have been a sandbar in an ancient river where carcasses came to rest during fl oods. Among the bony roll call: Stegosaurus, with its protruding spinal plates and spiked tail; Apatosaurus, also called Brontosaurus, whose long neck and longer tail gave it a total length up to 75 feet; and Allosaurus, the nightmarish relative of Tyrannosaurus rex. Paleontologists recently unearthed the fi rst complete North American sauropod skull from the Cretaceous period. Skulls are fragile and rarely found whole. This one belonged to an herbivore called Abydosaurus that lived about 105 million years ago. (Note: A new structure enclosing the quarry is expected to open in late 2011.)

Petrified Forest National Park: Colorful Fossilized Wood and Other Fossils of the Late Triassic
Staying on the whopping side of things, trees come after dinosaurs. When trees die, they normally decompose quickly. But if they become buried in the right sort of sediment, one fine-grained and rich in silica, decomposition is arrested. Water soaks into the wood, carrying minerals that gradually replace the organic matter, literally turning it to stone. The woody structure remains, but the original colors have been replaced by a glittering crystal rainbow of reds, blues, and yellows. The trees of Petrified Forest in Arizona grew during the late Triassic period about 200 million years ago, early in the age of dinosaurs. Growing conditions were good. Giant conifers rose 200 feet and higher above thickets of lush vegetation. Their fossil remains are scattered among the colorful clay hills of the Chinle formation. Trunks of the genus Araucarioxylon stand out for their size (up to 190 feet long) and their awesome petrified beauty. Other fossils help fill out the ancient scene: early dinosaurs, crocodile-like reptiles 40 feet long, half-ton amphibians, horseshoe crabs, clams, and freshwater sharks. Mammals were far in the future.

Florissant Fossil Beds National Monument: A Rich Deposit of Eocene Epoch Fossils
It is impressive that the 5-foot femur of a 30-ton Apatosaurus can survive 80-odd million years. For a tiny mayfly wing to do the same is downright boggling. The fossil femur weighs about 600 pounds. It was the size of a small tree trunk and pound-for-pound stronger. The mayfly practically defines its order name, Ephemeroptera, from the Greek ephemeros, or short-lived. Yet here it is, 34 million years later, the lightest of gossamer preserved between thin layers of shale. Colorado's Florissant is extraordinarily rich in fossil species; about 1,700 have been identified. They include the leaves of ferns, cypress, maple, mahogany, laurel, cocoa, and many others. Among the insects are dragonf lies, cicadas, lacewings, beetles, caddisflies, and yes, cockroaches. Fish are abundant, birds and mammals less so. Not all the fossils are delicate. Several huge petrified redwood stumps still stand upright behind the visitor center, which is loaded with fossil displays. The park has a roster of hands-on paleontology activities. Call ahead for schedules and availability.

Fossil Butte National Monument: Eocene Epoch Fossils at Fossil Lake
It was 50 million years ago, the Eocene epoch. Dinosaurs had suffered their catastrophic disappearance. In Wyoming and the surrounding region, the climate was subtropical. For about two million years, a large shallow lake, now called Fossil Lake, collected sediments and the bodies of creatures that lived in and around the water. The sediments today make up the Green River formation. Mingled with them are the river and stream sediments of the Wasatch formation. Both formations contain fossils, but the formation created by the lake sediments yields especially good fossils. In the lake's calm water, organisms tended to lie undisturbed and whole. Fine-grained sediments covered them like pages in a book. The monument protects a small piece of that book and features more than 80 opened pages in the visitor center. Every slab of stone is a work of art, revealing fossils galore. Fish are prominent, including Knightia, long-snouted gar, and stingrays. Also found are turtles, crocodiles, snakes, snails, birds, the earliest known bat, and an early horse. Insects include plant-hoppers, crickets, wasps, beetles, weevils, and dragonflies. Palm fronds, sycamore leaves, ferns, horsetails, flowers, and redwood leaves prove the warmer ancient climate.

Agate Fossil Beds National Monument: Miocene Epoch Remains: Early Mammal Fossils
Two buff-colored hills rise from a grassy plain beside the Niobrara River in Nebraska. They are important not for agates, which are found in other locations nearby, but for Miocene mammal fossils. About 20 million years ago, the area was populated by an odd assemblage of herd animals, predators, and rodents. The landscape was a savanna of grass and scattered water holes. Paleontologists theorize that a severe drought concentrated the animals near shrinking water sources, where they died close to each other. Some of the animals were similar to modern species; others were downright strange. There was a rhino the size of a dog with two small side-by-side horns on its nose. An 8-foot-tall chalicthere called Moropus had a horse-like skull, three-clawed feet like a sloth, and short hind legs. Dinohyus, or "terrible pig," was an omnivore described as a "cross between a bison and a pig with a whole lot of mean thrown in" and which stood 6 feet tall. There were little gazelle-like Stenomylus, delicate creatures the size of whippets. Land beavers lived away from water, digging corkscrew tunnels deep into dry ground. Imagine a long cat's tail on a heavy-jawed hyena, and you have something like Daphoenodon, or "bear-dog." They exist today only as well-displayed exhibits in the visitor center.

Published: 23 May 2011 | Last Updated: 10 Sep 2012
Details mentioned in this article were accurate at the time of publication
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