Summerasaurus Part IV: How to Find Dinosaurs

Posted: August 23, 2011 - 12:25 , by admin

Mark Farmer recently returned from an expedition to the badlands of southern Alberta with Dr. David Evans, Associate Curator of Vertebrate Paleontology at the ROM, in search of dinosaurs. Join us as Mark and Dr. Evans put up their notes from the field, detailing discoveries, how dinosaurs are found and excavated, life in the field and more.

In  one of the dramatic opening scenes of Jurassic Park, Sam Neill’s character uses ground-penetrating radar to take a snapshot of what’s hidden in the rock deep underground. He sets a small explosive charge to create the sound wave that will bounce around the layers of rock, and lo and behold… a picture of the fully-articulated skeleton of a raptor appears on his monitor, neck thrown back in a dramatic death pose, just waiting to be freed from the sediments below.

“Pretty soon, we’re not even going to have to dig anymore,” he says with an air of wonder.

It’s a striking cinematic moment, but mostly fantasy. Palaeontologists rarely (if ever) use fancy equipment such as ground-penetrating radar to find fossils. By far the most efficient and most reliable method is prospecting. The biggest part of prospecting involves the distinctly unglamorous, low-tech method of walking around with your head down to look for fossils. This is particularly effective, because (as the old saying goes) where there’s smoke there’s fire. Where there are pieces of bone sticking out of the surface, or washed down a canyon wall, there’s a good chance further fossils are waiting to be found where those pieces came from.

In fact, palaeontologists are a lot like detectives: they follow the trail of evidence. If they see a fossil on the ground, one of the next things they’ll do is look up. Since most fossil country (such as the Milk River area of southern Alberta where Dr. Evans just finished digging) is made up of canyons and coulees, fossils often erode out of valley walls and tumble to the bottom. This means that if you find a fossil lying on a canyon floor, you should look up to see if there are more fossils eroding out higher up, which will form a trail you can follow. Sometimes that trail can lead to larger bones, or even a partial skeleton. This is how palaeontologists spend much of their day: looking down.

Dr. David Evans and guest looking at microfossils

This is how palaeontologists spend much of their day - looking down

Of course, you increase your chances of discovery if you know what kind of rock to look in. Depending what kind of fossil you’re looking for, you need to look for a certain kind of rock. For dinosaurs, you are looking in rocks of Mesozoic age that are deposited on land or in inland river systems. Knowing the local geology is essential if you want to find fossils. Want to find marine life? Wind-blown sandstone is not a good place to look; marine shales or limestones would be good bets. Looking for dinosaurs? Layers of river-deposited sandstone and mudstone would be your best bets, and the boundary layers between different types of rock often yield good results.

Another myth about fossil hunting is that palaeontologists are always finding complete skeletons. These are indeed spectacular finds that make great TV, but skeletons that are even mostly complete are very rare. In fact, many important finds by palaeontologists are relatively fragmentary. The conditions the animal died in, scavenging, scattering of bones, weathering and other factors make it extremely unlikely to find an intact skeleton. However, that doesn’t mean partial remains aren’t very informative. Even single bones can provide insights into anatomy, growth, and behaviour of the animal it belonged to.

A piece of fossilized tendon

This scavenged piece of fossilized tendon has a story to tell

Sometimes, palaeontologists aren’t even looking for big bones – microfossils are an essential part of palaeontology. Microfossils are small specimens which might seem easy to overlook, but which paint an important picture. They include things such as teeth, fish scales, fragments of turtle shell, small vertebrae, pieces of tendon and very small bones that can litter the surface of rock outcroppings. By studying these fossils, palaeontologists can get an idea of the other life that was around the dinosaurs, and with that information they can start painting a picture of the environment and the diversity of the ecosystems the dinosaurs lived in. These small fossils can paint a big picture, and they’re often easier to find than the big bones that end up on a museum floor.

Ancient fish scale

An ancient fish scale, just one kind of microfossil

One advantage palaeontologists in 2011 have that Sam Neill’s character didn’t in 1993 is the widespread use of inexpensive geolocation technology. By recording the positions of finds for later use, palaeontologists can prospect a large area in the course of a day, and save the locations they think may deserve a second look. In fact, modern-day palaeontologists sometimes try to track down old quarries from field notes and photographs, because after decades of erosion, these sites can become excellent prospects themselves.

Of course, the best place to find dinosaurs is a lot closer than you think: click here to find out more.

See the Summerasaurus Dino series for more on the ROM’s hunt for dinos!

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