One October day in 1902, a group of curious students and teachers at Kincardine High School set out to gather fossils and rocks along the Penetangore River. Their goal was to assemble a small geological study collection for pupils of the school. A few days later, the local paper reported upon the delight and fascination experienced by students and teachers alike. Whether it’s 1902 or 2025, one irrefutable truth endures: fossils are just plain cool.
Many of the fossils in Bruce County date to the Ordovician, Silurian, and Devonian periods (roughly 480-360 million years ago), when Southern Ontario was much closer to the equator and warm shallow seas periodically covered the land. Due to the abundance of limestone deposits which formed here during this time, many fossils have been preserved in this region. Most common are ancient sea-dwelling creatures, such as trilobites, cephalopods, brachiopods, gastropods, and corals.
Twenty Thousand Trilobites Under the Sea
The fossils pictured below were discovered by a resident of North Bruce in 2012. Preserved in the rock, we see the impressions of two cephalopods (upper left and right) and a trilobite (lower middle).
Trilobites first appeared during the early Cambrian period, about 520 million years ago. Over a span of 270 million years, more than 20,000 different species of trilobite roamed the world’s oceans. Named for their tri-lobed bodies, these diverse critters evolved an array of body shapes, sizes, and exoskeletons and limb adaptations to help them thrive in various marine environments. Though trilobites went extinct around 250 million years ago, modern relatives include horseshoe crabs, scorpions, and spiders.
“Head-Foot” has Entered the Chat
Modern cephalopods include various species of octopus, squid, nautilus and cuttlefish. The name cephalopod comes from Greek and literally means “head-foot”. The first ancestors of this leggy, big-headed class of creatures made their debut in the early Cambrian period. Then, during the Ordovician period, cephalopods diversified and developed into successful predators, reigning as CEOs of the Sea (Sea-E-O, if you will) for millions of years.
Until the Cretaceous period, these soft-bodied creatures sported a variety of spiral and cone shaped shells. The 2 cephalopod fossils above showcase the many internal chambers into which their shells were divided. As the animal inside grew, it formed a larger chamber to move into and sealed off the smaller ones behind. A tube called a siphuncle ran though the chambers and drained remaining fluid, which allowed cephalopods to maintain buoyancy in the water. Of the over 800 species of cephalopod that exist today, however, only 8 still have external shells.
My, What Big Teeth You Have!
Imprints of primeval seafarers aren’t the only fossils found in Bruce County. In 1979, a fossilized woolly mammoth tooth was discovered in a farm field near Tara. It dates to around 12,000 years ago and weighs 2.5 kg. Mammoth teeth were made up of several plates stuck together in parallel sheets. This created a ridged surface for grinding the grasses and sedges they fed upon.
After the Laurentide ice sheet retreated from this area, large “mega-fauna”, including woolly mammoths, migrated into the plains north of Lake Erie. Thick wool undercoats and lush hair overcoats kept woolly mammoths warm and dry. This allowed them to live within a few kilometers of the ice front, grazing on the grassy plains nearby. They migrated alongside the shifting ice front, moving south when the ice expanded and north when it retreated.
Notes:
1: To protect the natural history and safeguard the natural future, many provincial and national parks now prohibit the removal of any material (including rocks and fossils) from their grounds. Instead, snap a picture or make a rubbing on paper.
2: The number of known species, both extinct and extant, belonging to any class or order of the animal kingdom will continue to change as new discoveries are made. Exact numbers may not reflect latest scientific discoveries and consensus.
Sources:
- Coumans, Camilla. “Immaculate Conception Church Formosa” in Bruce County Historical Yearbook, 1971. Page 11-12. The Bruce County Historical Society Yearbook 1971 – Bruce County Historic Newspapers – Bruce County Museum & Cultural Centre
- Encyclopedia Britannica. “Geologic Time”. Accessed March 2025. Geologic time | Periods, Time Scale, & Facts | Britannica
- Encyclopedia Britannica. “Trilobite”. Accessed March 2025. Trilobite | Cambrian period, Extinction, Arthropod, & Facts | Britannica
- Kincardine Review, October 23, 1902. “Looking for Fossils”. Page 1. The Kincardine Review 1902-10-23 – Bruce County Historic Newspapers – Bruce County Museum & Cultural Centre
- Lane Fenton, Caroll and Mildred Adams Fenton. The Fossil Book. Doubleday & Company, 1958. Print.
- Royal Ontario Museum. “Geology Magazine Publishes Two Articles Co-authored by ROM Palaeontologists”. News release, October 2007. https://www.rom.on.ca/en/about-us/newsroom/press-releases/geology-magazine-publishes-two-articles-co-authored-by-rom
- Smithsonian National Museum of Natural History. “Cephalopods”. Accessed March 2025. https://ocean.si.edu/ocean-life/invertebrates/cephalopods
- University of Waterloo Earth Sciences Museum. “Fossils of Ontario”. Accessed September 2024. https://uwaterloo.ca/earth-sciences-museum/resources/fossils-ontario
