The Bertie Waterlime - Fossil Ecosystems of North America: A Guide to the Sites and their Extraordinary Biotas - page 78

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82 Small sperm, Williamsville Formation
bed A, Ridgemount Quarries, Ontario YPM.
Length 3.5 cm 1.4 in.

83 Ezekiels Wheel, Williamsville Formation
bed A, Ridgemount Quarries, Ontario YPM.
Length 4 cm 1.6 in.

84

palaeocontinent of Laurentia and is still
the only locality in which to find
Laurentian Cooksonia . Banks's original is
a single specimen, without counterpart,
and is preserved as an impression with
patches of coalified residues on the
dolomitic limestone. It consists of a cluster
of axes (branches), three of which
terminate in short, wide sporangia.
Recently, many more specimens were
discovered by Sam Ciurca, and were
described by Edwards et al . (2004) ( 84 ).
Cooksonia is a simple vascular plant
with smooth, presumably green stems
which branch dichotomously (in equal
parts, unlike most modern plants which
have a main trunk and side branches).
The clumps grow by branching and
expand by creeping along the ground.
Sporangia are borne at the tips of the
fertile axes, rather than at the side, as
occurs in higher plants.

84 The simple vascular plant Cooksonia, showing
dichotomously branching axis and terminal
sporangia. Williamsville Formation, Ridgemount
Quarries, Ontario. Length 6.5 cm 2.6 in.