Forest Footprints

A light brown Brachiosaurus walks beside the fossil trackway, an exposed rocky patch of ground with blue tarps strewn around it. Several people walk around the fossil site. They are tiny in comparison to the Brachiosaurus. The dinosaur takes huge steps as it walks on all four legs. It’s enormous tail swings behind it as it turns its even longer neck to look at the people.

Richard: Footprints are found in a variety of depositional environments, and it’s just like any other thing. For footprints, modern footprints, you have a human footprint and you walk on certain substrates like sand or a mud, firm sand, wet sand. You name it.

Ariel view of a fossil track site, an exposed rocky patch of ground with blue tarps strewn around it. Several people sit on the ground looking at the tracks. The camera slowly pans over the length of the site.

Lisa: That footprint is gonna look different.

Richard: It is. Sometimes it’s not gonna look like much at all. You’re not even going to be able to see toes.

Silhouettes of a girl (1.3 metres tall) and a man (1.7 metres tall). The camera pulls out to reveal silhouettes of dinosaurs that increase in size. An ankylosaur 1.5 metres tall and 5.5 metres long. A therizinosaur 3 metres tall and 5 metres long. A medium theropod 3 metres tall and 8.5 metres long. A large theropod 3.5 metres tall and 10 metres long. A hardrosaur 4.75 metres tall and 9 metres long. A sauropod 15 metres tall and 18.5 metres long. Their footprint shapes are shown below them.

Three bird feet are lined up: a goose’s foot with small rounded claws and webbing between its toes; A black raven’s foot, small in comparison to the other two with pointy hooked claws; and an eagle’s foot with large talons and long pointy claws.

Ildiko: So one of the questions that I was asked today is: if I saw bird footprints, would I have an idea of what it liked to eat? And I would say very much. So I would know that if I saw webbing that this is a bird that preferred aquatic habitats, and that it’s probably a herbivore, a vegetarian, or an omnivore. If I saw the middle foot of the raven, I would know that this is a bird that likes to cling on branches, and again, it’s probably a generalist and likes to eat all sorts of things. But if I saw the eagle foot, I would see all the power, and I would know it’s a carnivore. My name is Ildiko Szabo. I’m the collections curator of the Cowan Tetrapod Collection here at the UBC Beaty Biodiversity Museum.

A woman with grey chest-length hair and glasses looks at the camera.

Aerial shot looking down at a greyish-brown rocky ground. There are several people sitting down. The camera slowly moves in getting closer to the ground. Holes in the ground become more noticeable. Eventually one takes up most of the frame and we see it is a big sauropod footprint.

Richard: When you study tracks and trackways, you’re seeing the actions of animals that were alive when they made those traces. So you’re getting a lot of an idea of how the animals used their anatomy, what other animals they’re walking around with, and what environments they were frequenting. And you know what kinds of behavior they had, whether they were traveling in groups or singly, or all kinds of things that you just can’t get from bones.

Two theropod silhouettes walk together in a big arc across the frame. One leaves green footprint outlines. The other leaves yellow footprint outlines. A single silhouette of an ankylosaur walks across the frame leaving orange front and rear footprints.

A big flock of gulls and royal terns gather on the beach.

Ildiko: Birds do many, many things in large groups. They gather when there’s a lot of food in one particular area, and there’ll be a lot of individuals of one species, plus multiple species.

Swans and geese swim together in the water. Gulls sleep together standing in shallow water.

Ildiko: They also like to sleep together in large groups. This is to avoid predation. And the ones on the outside of the group act as sentinels, yelling if they perceive an intruder.

Crows roost in a tree. A large flock of birds flies over a lake.

Ildiko: And birds, often when they’re nesting, they like a particular area that they find very safe or has lots of nesting possibilities. And again, they’re in very large groups.

Two American coots build a nest. Many albatrosses nest together in an open field.

Ildiko: My name is Ildiko Szabo. I’m the collections curator of the Cowan Tetrapod Collection here at the UBC Beaty Biodiversity Museum.

A woman with grey chest-length hair and glasses looks at the camera.

An image of rocky debris is shown next to an image of dark brown dirt.

Sam: What is the difference between sediment and soil? Sediments are deposits made up of broken pieces of bigger rocks, like sand or gravel.

Magnified many times, sand looks like tiny yellow rocks. From a regular distance we can see the many fine particles making up the sand.

Sam: Soil is special. Soil is a type of living deposit where water, plants, animals, and microorganisms all work together to change the rocks around them.

Several images flash by quickly. A puddle of water on top of soil. Green sprouts emerge from damp soil. A pink worm lays curled on top of some dirt. A microscopic images of soil microbes. A soil profile showing different soil horizons.

Sam: Soil forms from rock and we call this rock the parent material. Any type of rock can become a parent material. Parent material on the Earth's surface is exposed to water. This water can trickle through tiny cracks, opening spaces for plant roots to take hold. The water also changes the rock through chemical reactions that breaks it down into smaller pieces.

Animation. Water rains down on the parent material. The parent material starts to crack and weather. Small plants start to grow, their roots spreading down into the parent material. This creates the c horizon made of weathered rock.

Sam: As more rock is broken down larger plants start to grow on top. Dead plant matter falls to the ground and it makes a deposit called humus, a mix of weathered rock and organic matter.

The parent material break down further. Larger plants start to grow in it. Humus builds up on the top. The A horizon of the soil starts to form.

Sam: Over a very long time as water continues to seep down through the soil. The layers of weather rock just underneath the humus go through so many chemical changes that it becomes the simplest rock type, clay. The result is a soil with distinct layers or horizons.

It continues to rain. The water drips down through the A horizon and starts to form the B horizon. The B horizon is made up of clay. The A B and C horizons stack on top of each other creating a soil profile.

Arial shot looking down onto the fossil site.

Sam: Today this area is rich in coal deposits, but what can this tell us about the past?

Exposed layers of black coal are visible, sandwiched in between other rocks.

Sam: Coal is made up of carbon which comes from organic matter. All living things are made up of organic matter.

Animation. A zoomed in image of a carbon atom. The atoms start to multiply. The camera zooms out to reveal a plant filled swamp 300 million years ago. Some plants die and new ones take their place.

Sam: So when living organisms die, they leave behind a layer rich in carbon, but with lots of impurities. Normally, organic matter breaks down easily. However, if it's buried in conditions with no oxygen, it can form a thick layer of preserved plant matter called peat.

The dead plants build up on the ground and create a thick layer. 100 million years ago the sea level rises over the swamp. Other sediments start to build up on top of the peat. The peat is squeezed underneath the new sediments.

Sam: As new sediments get deposited on top, the pressure and heat cause the peat to undergo chemical reactions. This removes some of the impurities and leaves behind even more carbon rich material called lignite.

The sea level falls and the ground above the lignite is no longer under water. The lignite continues to be squeezed even further.

Sam: With even more heat and pressure, most of the impurities are removed from the lignite. What's left behind is a deposit that is almost pure carbon. That is what we call coal.

The camera pans across a mountainous landscape. Orange lines highlight the smaller tree covered foothills that are nearby. Yellow lines highlight the tall snowy peaks in the distance.

Sam: Tectonic forces create mountain ranges, but mountains don't just pop up in the middle of a flat field. The highest peaks are found in the main ranges of a mountain chain. As you move further away from these peaks, you find smaller peaks and hills. These are called foothills. Foothills are usually the youngest part of the mountain range. Tectonic forces just started to push them up, but over time, they might become just as high as the main ranges.