Joseph Moysiuk, Author at Manitoba Museum

Posted on: Wednesday March 19, 2025

Geologic time is truly staggering. It is hard to comprehend even for geologists, so we often rely on analogies to convey the vastness of time. If you could count one year per second, it would take an hour and 17 minutes until you had counted the age of the oldest Egyptian pyramids. Keep going, and it would take over 2 years before you reached the end of the age of dinosaurs. You would have to keep going for another 5 and a half years to get to the age of the earliest dinosaurs and another 12 on top of that to reach the earliest animals. It would be impossible to count to the age of the Earth, as it would take 144 years to get to 4.54 billion.

But, how do we actually know how old a particular specimen or event is? This is one of the most common questions I am asked as Curator of Palaeontology and Geology. It’s an excellent question, but not an easy one to answer in a concise way, so I will do my best to provide a more comprehensive answer here.

The Ancient Seas exhibit, showing a large curving monitor with an animated sea scape representing the tropical ocean that once covered much of Manitoba. Boulders covered in colourful corals and algae give way in the foreground to more open areas where cephalopods with coiled shells swim. Below the screen are small cases, text, and graphics.

Manitoba has changed immensely over Earth’s history. While Churchill is now a cold, arctic environment close to 60 degrees north of the equator, about 450 million years ago it was equatorial and covered by a tropical sea. This is due to the shifting of the plates that make up the Earth’s crust, which move at about the speed that your fingernails grow.

Rocks and Clocks

You may have heard of carbon dating before. This approach relies on the radioactive decay of a naturally occurring form of the chemical element carbon. As with all elements, carbon atoms can come in several different forms, called isotopes. Isotopes share the same number of positive particles (protons) in their atomic nucleus, but differ in the number of neutral particles (neutrons). The majority of carbon on Earth is an isotope called carbon-12, which is stable. However, other forms of carbon exist, including an unstable form called carbon-14, characterized by two extra neutrons in its nucleus. Carbon-14 atoms decay over time, as one of their neutrons converts into a proton, releasing radiation and transforming the unstable carbon atom into a stable nitrogen atom. New carbon-14 is constantly being generated in the atmosphere by the action of cosmic rays from space which cause the conversion of nitrogen atoms into carbon-14.

Critically, the decay of carbon-14 happens at a predictable rate. By measuring this rate, we can predict that half of the carbon-14 that exists now will have decayed in 5,730 plus or minus 40 years. This length of time is known as the half life of carbon-14 and it is this concept that allows us to date materials made of carbon. Living organisms take in carbon, including carbon-14, either from carbon dioxide gas via photosynthesis or from feeding on other organisms. While organisms are alive, their supply of carbon-14 is continuously replenished. Once they die, carbon intake ceases and the carbon-14 “clock” is started. By measuring the amount of carbon-14 remaining in a sample of an ancient organism, we can calculate how long ago it died.

An exhibit case in the Earth History Gallery with several specimens arranged along a timeline.

One of the oldest rocks on the surface of the Earth, called Acasta Gneiss, on display in the Earth History gallery. It is close to 4 billion years old and is found in Northwest Territories. The age of the Earth and Solar System are estimated to be even older based on measuring the age of meteorites and samples from the moon, which are less subject to processes that reset the radiometric “clock”.

Unfortunately, there’s a catch: if a sample is more than about 50,000 years old, the amount of carbon-14 remaining will be too small to permit an accurate age estimate. For older samples, scientists have to rely on different elements. For example, uranium-238 decays into lead-206 with a half life of about 4.47 billion years. Since uranium-238 is commonly trapped in in certain minerals when they form, it is ideal for measuring the age of older events in Earth’s history. Several other clocks, or more technically radiometric dating systems, exist and these can often be compared to each other to improve the accuracy of estimates.

Absolute and relative time

Not every sample can be dated using an absolute method. For example, many fossils are too old for carbon dating and have insufficient uranium content for uranium-lead dating (although new approaches are pushing the boundaries of what is possible).

Similarly, sedimentary rocks like sandstones and limestones are formed of many different components including fragments of older rocks, fossils, and mineral crystals that have grown in between. Dating these components can give differing ages, sometimes producing misleading age estimates for samples. Further, alteration of rock under high heat and pressure or by the seeping of groundwater can enable atoms to move into and out of its crystalline structure (element mobility), which can “reset” the radiometric system.

This is where a second, complimentary approach called relative dating comes in. Even before there was a well-developed conception of evolution, scientists noticed that there was a regular pattern to the occurrence of different species throughout Earth’s rock record. We now know that this pattern is a consequence of the evolution and extinction of species. Mammoths, dinosaurs, and trilobites are all found only in particular rock layers and are absent from others. At a finer scale, careful examination reveals multiple successions of particular species, from which a comprehensive sequence can be built up. Since rock layers are deposited one on top of the other, the ordered succession of organisms gives us a clue about the relative age of the layers they are found in. If we can date rock layers above and below a particular fossil using radiometric dating, then we know that the fossil must be intermediate between those ages. If we then find the same fossil elsewhere, we have a relative idea of how old the rock it occurs in must be.

This section of rock on display in the Earth History Gallery is the boundary between the Cretaceous and Paleogene Periods, marking the end of the age of dinosaurs. Radiometric dating has allowed precise age estimates for this boundary layer, recently placing it at 66.02 plus or minus 0.08 million years.

The time scale in the Earth History gallery shows the names of major time intervals. The cylindrical rock slices are pieces of rocks of each interval found in Manitoba. Some time intervals are not represented in our province, corresponding to gaps in the time scale. Since this display was constructed, there have been changes and refinements to the time scale that will require updating in the future.

Fossils are not the only source of information that can be used for relative dating. Chemical and magnetic signatures also exhibit observable patterns of change through time that can be used to order rock layers by age. By combining insights from various relative and absolute dating methods around the world, the Earth’s timescale has been built up. The timescale is broken up into a number of named intervals, often based on particularly noticeable changes in the types of fossils. For example, the end of the Cretaceous Period is marked by the extinction of the dinosaurs, with the exception of birds.

Earth’s geological time scale should certainly be ranked among our most significant scientific achievements. This is the result of a long and fascinating history, with insights being drawn from multiple different disciplines of study around the globe. While we now have a pretty good idea of the age of key events throughout Earth’s history, new research is constantly refining dates, enabling us to understand events in the deep past with ever increasing precision.

Dr. Joe Moysiuk

Curator of Palaeontology & Geology

Joe Moysiuk recently completed his doctoral dissertation at the University of Toronto and Royal Ontario Museum. His expertise centers on the oldest animal fossils and insights they provide about the evolution…

Meet Dr. Joe Moysiuk

Museum Stories: Palaeontology & Geology

Palaeontology & Geology

Wednesday March 19, 2025

Posted on: Friday February 16, 2024

Animals today are mindbogglingly diverse, encompassing flies and flamingoes, elephants and earthworms, sharks and snails, and of course, ourselves. It’s hard to even imagine a world before animals, or how such staggering diversity came to be.

My name is Dr. Joe Moysiuk and I am the new Curator of Palaeontology and Geology at the Manitoba Museum. It’s my job to reconstruct ancient worlds through scientific study of the evidence that remains – fossils and rocks – and bring them “back to life” for museum visitors. I’m particularly fascinated by the evolution of major groups of animals and have devoted the past several years to researching fossils from the Burgess Shale, a UNESCO World Heritage Site and one of the world’s most significant palaeontological discoveries.

Famous shale

The Burgess Shale is located high in the mountains of Yoho and Kootenay National Parks in British Columbia. Fossils were discovered by workers during the construction of the Canadian Pacific Railway in the 1880s. Although a few sites were explored by earlier researchers, it wasn’t until 1909 that Charles D. Walcott of the Smithsonian Institution made the famed discovery of a particularly diverse excavation site and provided the name Burgess Shale after the nearby Mount Burgess. Subsequent expeditions by Harvard, the Geological Survey of Canada, and Royal Ontario Museum (ROM) have yielded large research collections that have been scrutinized by countless scientists and popularized in books like Wonderful Life by legendary palaeontologist Stephen J. Gould. Collection and research continues, notably at ROM, my previous institutional home.

The Burgess Shale fossils date back roughly 506 million years, to the Cambrian Period – long before the dinosaurs or even the earliest evidence of large lifeforms on land. At first glance, they are not particularly charismatic; most appear as small, dark stains on dark rocks and are difficult to see without special lighting conditions. Contrary to their modest appearance, these fossils have had an outsized impact on our understanding of the origin and evolution of animals.

Four people viewing a fossil in Walcott's quarry. The face of the quarry is a vertical cliff about 8 meters high

Walcott’s quarry today, showing the marks of 100 years of excavation.

Not your ordinary fossils

When I mention the word fossil, dinosaur bones may come to mind. Alternatively, you might recall seeing the shells of molluscs and corals in the Tyndall stone walls of buildings that dot the streets of Winnipeg or other Canadian cities. These sorts of hard, mineralized remains of organisms are resistant to decay, scavenging, and breakage, so they have a decent chance of persisting long enough to become fossilized. The softer parts of organisms, like eyes, digestive tracts, or brains tend to be lost long before they can be buried and preserved from further degradation.

However, there are some fossil deposits that defy these rules, preserving traces of the soft tissues of organisms alongside their mineralized bits. In technical parlance, we call these sites Konservat-Lagerstätten, deriving from an old German mining term for “conservation motherlode.” The Burgess Shale is one such Lagerstätte, and the exceptional quality and quantity of fossil material has made it among the most renowned.

A fossil of Stanleycaris, showing the head on the right and multisegmented body extending to the left. The eyes are large and situated on stalks. A pair of claws extend forward from the head and a circular mouth is visible. Inside the body we can see remains of the gut and nervous tissues

A specimen of Stanleycaris, a smaller relative of the more famous Anomalocaris. This fossil is exceptional even by the standards of the Burgess Shale – the dark matter in the head and extending into the bulbous eyes is the remains of the brain and associated nervous tissues. Photo by Jean-Bernard Caron, © Royal Ontario Museum, used with permission.

A pair of flattened jellyfish fossils with bell-shaped bodies lined with dozens of short tentacles.

A pair of Burgessomedusa phasmiformis, the oldest jellyfish known from the fossil record. These fossils were collected in the 1980s, but the species was only formally described last year. Photo by Jean-Bernard Caron, © Royal Ontario Museum, used with permission.

As you can imagine, soft tissue preservation provides unique insights about past life. For example, we recently uncovered fossilized elements of the nervous system of Stanleycaris hirpex, a distant relative of modern insects, spiders, and crabs, giving us extraordinary direct evidence of the form of the brain in the common ancestor of these disparate animals. We also find representatives of entirely soft bodied groups of organisms, which would never be found in a typical fossil deposit. For example, my colleagues and I recently described the oldest definitive swimming jellyfish.

The reasons behind the exceptional quality of preservation at the Burgess Shale, and other similar sites around the world, remain the subject of research. It’s generally thought that a combination of factors played a role: rapid burial of the organisms in undersea mud flows, low oxygen near the sea floor, and unusual sea water chemistry during this time in Earth’s history. Subsequently, chemical reactions during rock formation reduced the organic remains to carbon-rich traces which were resistant enough to survive for over half a billion years.

Aside from the quality of preservation, the age of the Burgess Shale makes it particularly significant. The Cambrian Period witnessed a spectacular diversification of animals. Essentially all major groups that are with us today can trace their roots back to this time. The Burgess Shale provides a window into life on Earth shortly after this pulse of animal diversification.

Opening new doors to ancient worlds

I started my museum career at a particularly exciting time. Field work at the Burgess Shale had just resulted in the discovery of a brand new Burgess Shale site in the vicinity of Marble Canyon in Kootenay National Park. This site lies a mere 40 km south of Walcott’s quarry, but differs substantially in terms of the fossil species present. For several summers between 2014 and 2022, I joined international crews in exploring the region and excavating several dig sites systematically. Access to the sites is challenging and mostly by helicopter. We would camp in these remote settings for 2-6 weeks at a time, hiking long distances to reach fossil-rich outcrops. The work was hard and physical, but the rewards were truly spectacular. In the early days of exploration, new fossil species tumbled out of broken shale on a near daily basis. Some of these finds have now been formally published, but many still await attention and will be the basis of years of research to come.

Campsite from 2018. Finding a flat area to pitch multiple tents can be challenging in the mountains.

One of several excavation sites developed over the past decade in the vicinity of Marble Canyon, Kootenay National Park.

Using a rock saw to extract fossils from a block of shale.

A fossil of Marrella splendens, showing curving spines on the head, antennae, and numerous feather-like limbs. This animal is extremely common at the Burgess Shale and is a distant relative of insects and spiders.

The feeding claw of Anomalocaris, one of the largest predators from the Burgess Shale. This animal belongs to an early branch in the arthropod group, close to the common ancestor of insects, spiders, and crabs.

Getting fossils out of the mountains is no easy task! Here we employ a net suspended on a longline below a helicopter.

Given its protected status, collecting fossils at the Burgess Shale is by permit only. However, guided hikes are available to the intrepid fossil enthusiast through Parks Canada and the Burgess Shale Geoscience Foundation. For those unable to make the somewhat arduous journey to the site, a selection of Burgess Shale fossils are on permanent display in the Earth History Gallery of the Manitoba Museum.

As I begin my tenure here at the Manitoba Museum, I feel equally excited about the potential for fantastic scientific discoveries. A legacy of field work has yielded important collections from three Konservat-Lagerstätten here in Manitoba. At roughly 445 million year old, these deposits are slightly younger than the Burgess Shale. They therefore provide complementary snapshots of early animal diversification. I look forward to “digging into” these collections and sharing new insights in the coming years.