Localities of the Ordovician:

The Lake Winnipeg Algal Flora

Winnipeg is more than a large Canadian lake; it is also an area rich with fossil remains of marine plants and animals. The first fossils from this area were found in 1819 in limestone along the lake's shore, and new species continue to be found there.

The first fossil algae from the Lake Winnipeg area were collected by T. C. Weston in August of 1884. These specimens and additional collections made in 1890 and 1894 were first described and published in 1895 by J. F. Whiteaves in the Canadian Record of Science. The remarkable preservation of these Late Ordovician algae was not fully appreciated at the time. Not until G. Winston Sinclair of the Geological Survey of Canada colected several additional well-preserved fossils was interested sparked again.

Wayne L. Fry, of UCMP, published a full summary and description of the Lake Winnipeg algal flora in 1983. In this paper he demonstrated the algal origin of the fossils and formally named or revised the names of the nine genera and eleven species known. It is rare to find such a diversity of fossil algae in a single location, and even rarer for so many of these algae to be soft-bodied. Most fossil algae are those with mineral skeletons, which presumably are more resistant to decay. What is remarkable about the algae from Lake Winnipeg is that the fossils are mostly those of soft-bodied seaweeds.

Winnipegia Manitobia Kinwowia
Fossil Macroalgae : On the left, a fossil of Winnipegia cuneata, the most common alga in the Lake Winnipeg flora. At center, Manitobia patula, a putative member of the Floridean red algae, a group found today in warm seas. On the right, Kinwowia articulata, a feathery alga that may belong to the green algae.

Algae from Lake Winnipeg are preserved as reddish or brown compression fossils with traces of organic residue, but with little structural detail. The rocks in which they are preserved are marine deposits of gray or yellow dolomite, a material composed largely of carbonate. In addtion to algae, numerous fossils of algal microorganisms and marine invertebrates have been found, including more than sixty species of cephalopods.

Most of the Winnipeg algae resemble marine red or green algae of today. Living species similar in shape to the fossil algae occur today primarily in tropical or subtropical shallow marine waters near the coasts of continents. Tectonic evidence also suggests a tropical environment; North America lay near the equator during the Ordovician.

Source: Wayne L. Fry, 1983. An algal flora from the Upper Ordovician of the Lake Winnipeg Region, Manitoba, Canada. Review of Palaeobotany and Palynology 39: 313-341.