You'll find lots of Trilobites (Pseudogygites Latimarginatus) and brachiopods (mucrospirifer) just about anywhere you look in southern Ontario. Keep an eye out for shale piles left by construction, or if you're driving around in rural areas look for road cuts through sedimentary layers, the layers are exposed at the side of the road and you can easily find exposed fossils there. You'll need tools and safety equipment: a standard builder's hard hat is the minimum that should be worn in areas that are liable to falling rocks, especially cliff faces and within quarries, a high visibility jacket will improve your chances in case of an accident. Pick up a geological hammer if you don't have one. It's got a square head on one side, and a chisel tip on the other side. Useful for splitting the layers. Also, safety glasses are essential. You don't want to get a rock splinter in your eye. There's a more comprehensive tool list here "Most of Ontario's fossil record is found in the Paleozoic rocks that cover much of southern Ontario and the James Bay Lowlands. These rocks were deposited during the Ordovician, Silurian, and Devonian periods (450-350 million years ago) when Ontario was repeatedly covered by warm, shallow inland seas. The seas were fed by rivers draining from the bordering highlands of the Canadian Shield and acted as settling basins for thousands of meters of sand, mud, and clay. Eastern and northern boundaries of Paleozoic outcrop run roughly through the southern borders of Muskoka and Haliburton just east of Kingston (where Ordovician rocks lap onto Precambrian rocks). Ordovician rocks here abound with fossil snails, clams, squid-like nautiloids, trilobites, starfish, and sea lilies. Late Ordovician and Silurian rocks form the Niagara escarpment that runs from Manitoulin Island to the Niagara Peninsula and on into New York State. The escarpment was formed by rivers draining highlands to southeast. Fossils are scarce here. Silurian corals formed reefs that are now exposed as fossils on Manitoulin Island. Devonian rocks on shore of Lake Huron near Kettle Point contain abundant corals and trilobites, sea lilies and other marine invertebrates. Even the bony skin plates of early armored fish have occasionally been found. Unconsolidated deposits of Pleistocene Epoch are the next great chapter in Ontario's fossils. One of the most complete successions of interglacial sediment is exposed in Toronto Brick Pit. Fossils found here include wood, insects, freshwater clams and snails, antlers of deer, skulls of large bears, groundhogs, bison and giant beaver. Near Welland mastodons, wooly elephants, and pollen grains have been found." Ontario's Fossil Story By: Kristina Anderson, assistant curator Answer from 248_RPA on reddit.com