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magazine / jf04
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January/February 2004 issue |
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Life’s impressions
Canada’s fossil record tells the story of life as
we know it
By Steven Fick and Elizabeth Shilts
The book of life spans some 3.85 billion years and opens with the turbulent Earth erupting
in chemical reactions that allow for the birth of crude single-celled organisms. Each successive
chapter introduces new life forms, new scenery, new interactions — and ends with the demise
of the principal characters and the prospering of once minor players.
Much of this wild tale of extinctions and successions can be told in Canada, where rock
of all ages holds fossil evidence for almost every chapter of life.
A fossil is an impression, a trace or the actual preserved parts (mineralized or not) of
a plant or animal left in the Earth’s crust. From the more than two-billion-year-old bacteria-like
cells embedded in the Canadian Shield to the faint impressions of soft-bodied sea animals
in Newfoundland to the skeletons of huge badgers and beavers
in the North, the country’s fossils have helped shape our understanding of geology, past
climates and evolution.
“The crust of the earth is a vast museum,” wrote Charles Darwin, the father
of evolution, “but the natural collections have been made only at intervals of time immensely
remote.” Indeed, considering the destructive shifting and reshaping of the continents over
time, it is a wonder scientists are able to locate any fossils at all. But armed with the
understanding of geological deposits and a bit of serendipity, paleontologists have unearthed
many world-renowned fossil sites within Canadian borders. Here, we map some of the most important
ones.
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| Fossil Sites
1. Gunflint chert (Northern Lake Superior, Ont.)
Holds one of earliest-known records of life: two-billion-year-old micro-fossils resembling
modern iron-loving bacteria. Their discovery in the 1950s quadrupled duration of
fossil record on Earth.
2. Mistaken Point, N.L.
Oldest multicellular organisms found on Earth, known as Ediacaran fauna.
Soft-bodied, sea-dwelling creatures buried by layers of volcanic ash at end of Precambrian,
which marks the rise of Earth’s earliest animals.
3. Burgess Shale (Field, B.C.)
Unesco World Heritage Site. More than 120 species of ancient reef animals,
many not found elsewhere. Turned understanding of evolution on its head; suggested
biodiversity was higher in Cambrian period than it is today.
4. Tyndall stone (Garson, Man.)
Relatives of modern sponges, snails, squid and crabs indicate presence of
warm, shallow sea over mid-North America. Today, limestone used in many Winnipeg buildings
and in Parliament Buildings in Ottawa.
5. Parc national de Miguasha, Que.
World Heritage Site. Best example in world of life during age of fish. Has
five of six fossil fish groups from period and most lobe-finned fish fossils, which
gave rise to first four-legged, air-breathing land vertebrates.
6. Joggins, N.S.
World-renowned for primitive amphibians and some of the world’s earliest
reptiles. Animal remains are well preserved in tree stumps that were flooded, filled
with sediment and fossilized.
7. Dinosaur Provincial Park, Alta.
Conditions in region 75 million years ago ideal for preserving dino bones.
Fast-flowing, sediment-laden rivers buried animals whole. Some 400 partial and complete
skeletons unearthed, including about 35 rare species. Also a World Heritage Site.
8. Old Crow Basin, Y.T.
Richest Canadian site for extinct ice-age vertebrates, such as giant beavers
(left) and woolly mammoths. Discovery helped scientists understand animal migrations
over former land bridge across Bering Sea. |
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