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Fossil jaw from northeastern Colorado
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Vertebrates (animals with backbones) encompass a huge variety of organisms, including fish, turtles, dogs, birds, dinosaurs, and people. Yet despite our diversity, we vertebrates actually comprise just a small minority of the animal life on this planet. This relative rarity is reflected in the fossil record; both plant and invertebrate fossils are more numerous than vertebrate fossils.
Although some vertebrate fossils are fairly common, such as some species of fish, many are quite rare. So how do paleontologists find vertebrate fossils? Sometimes luck and — many times — knowing where to look.
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Badlands around Marmarth, North Dakota
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- Fossils can be found in any kind of environment,
but they're hard to find in wet regions supporting a lot of vegetation.
Badlands, arid areas with rocky outcrops, have little vegetation and
instead sport plenty of bare rock that might be rich with fossils. It
seldom rains in these areas, but each time it does, the water carves
a little deeper into the sediment and exposes more fossils.
- Freshly exposed outcrops, such as road cuts and construction sites,
are favorite spots of paleontologists since they also reveal new fossils.
- There are three basic kinds of rocks: igneous, formed from melting
rock; sedimentary, eroded by wind or water and later redeposited; and
metamorphic, changed by extreme heat or pressure. Almost all fossils
are found in sedimentary rocks.
- Paleontologists pay attention to past finds since areas that have yielded good fossils in the past might produce more in the future.
Before collecting any fossils, paleontologists must pay careful attention to who owns the land and seek the proper permission from the landowner or governing agency.
Depending on where paleontologists collect, field season can be short. In many places, snow might fall for all but two or three months of the year. (More than once, paleontologists have woken up on a brisk June or September morning to find themselves under a thick blanket of snow.) To avoid predicaments like this, paleontologists usually go collecting in the middle of the summer, sometimes in punishing heat. Hats, sunscreen, and plenty of water are necessities. So is camping gear, when the fossil site is far from modern conveniences. Dreaming of far-off showers, paleontologists spend days, sometimes even weeks, living in primitive conditions.
Not only rare, vertebrate fossils are often delicate. Vertebrate paleontologists must tread softly and look carefully. Big bones might be visible from a distance, but small bones and teeth are just as valuable, and they can only be seen at close range. Depending on the fossils they seek, vertebrate paleontologists might walk the surface, or crawl on all fours. In microsites (fossil localities with tiny fossils) paleontologists may end up flat on their bellies.
Fossil turtle carapace
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In 1995, the Denver Museum of Nature and Science opened its award-winning Prehistoric Journey exhibition, tracing the history of ancient life on Earth. The exhibition featured a wide range of vertebrate fossils, some of them new to science. One of the fossils DMNS staff and volunteers collected was a Cretaceous turtle, near Marmarth, North Dakota. This follows that turtle — along with some other vertebrate fossils — from the outcrop to the Museum's display case.
© 2000 DMNS. All rights reserved.
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