Eurypterids
Specimen of the Month
Samuel J. Ciurca, Jr., Rochester, New York        by  Eurypterids.net
DECEMBER 2009
Some Plants & Plantlike Forms
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The eurypterid-bearing waterlimes of New York carry plant and plantlike material associated with the fauna. This is
expecially true of the Williamsville (Waterlime) Formation, Bertie Group of southwestern Ontario, Canada and
upstate New York from Buffalo eastward to Syracuse. Perhaps the most commonly encountered are remains of a
large seaweed called
Inocaulis. It was originally thought to belong with the graptolites (animals), but is now generally
regarded as an alga. It must have floated around, as often seaweed does, because many large masses have been
found over the years flattened on bedding planes of the very fine-grained dolostones.
Cooksonia - see, for example:
New Silurian cooksonias from dolostones of north-eastern North America
D. EDWARDS 1*, H. P. BANKS 2 , S. J. CIURCA JR 3 and R. S. LAUB 4
1 School of Earth, Ocean and Planetary Sciences, Cardiff University, PO Box 914, Cardiff CF10 3YE, UK
2 Deceased, formerly at Department of Plant Sciences, Cornell University, Ithaca, USA
3 54 Appleton Street, Rochester, NY 14611-2510, USA
4 Buffalo Museum of Science, Humboldt Park Way, Buffalo, NY 14211, USA
Correspondence to   *E-mail: edwardsD2@cardiff.ac.uk
Copyright 2004 The Linnean Society of London
KEYWORDS
eurypterids • graptolites •
Hostinella • hypersalinity • Inocaulis • Přídolí
ABSTRACT
New specimens of Cooksonia and Hostinella are described from the Bertie Group of Ontario and New
York State, which is dated by faunas as latest Silurian (Přídolí). The rare plant fossils are unusual in
that they are preserved in fine-grained, slightly argillaceous dolostones ('waterlime') rather than clastic
rocks. At least two species of Cooksonia are present, one with ± globular sporangial morphology close
to
C. hemisphaerica Lang. Those with ellipsoidal/discoidal sporangia are compared with C. pertoni
Lang,
C. paranensis Gerrienne et al. and C. bohemica Schweitzer, the latter represented by a single
specimen from the Přídolí of the Czech Republic. However, the paucity of specimens, which prevents
assessment of taphonomic influences on shape, combined with the absence of any anatomical
features and the gross morphological simplicity of the fossils, precludes specific assignment.
Specimens of
Hostinella include one in which apices and a lateral basal structure resembling a root
are preserved. It is concluded that the Laurentian assemblage of Ontario and New York State is less
diverse and disparate than coeval assemblages, which are also preserved in marine rocks. Its
preservation in limestones may have been facilitated by the hypersalinity inferred from various
sedimentary features, which would restrict the activity of many decomposers.  © 2004 The Linnean
Society of London, Botanical Journal of the Linnean Society, 2004, 146, 399–413.
ABOVE & LEFT: The 'Finger Plant' from
the Late Silurian Williamsville Waterlime,
Bertie Group of New York and Ontario,
Canada (
Inocaulis lesquereux). In this
specimen, note the preservation of a thin
medial (conducting) strand. It is not ac-
tually known whether Inocaulis was a
floater, or was attached to the sea floor
or some object. This exceptionally nice
specimen is in the collection of Joseph
LaRussa of Rochester, New York.
For a closeup view of a stem showing the
multitude of fine filaments attached, see:
D. Edwards, H. P. Banks, S. J. Ciurca,
Jr., R. S. Laub (2004) NEW SILURIAN
COOKSONIAS FROM DOLOSTONES
OF NORTH-EASTERN NORTH
AMERICA. ...
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BELOW: The 'Medusa Plant' - Medusaegraptus mirabilis.  While relatively rare, Medusaegraptus occurs in
extraordinary numbers in certain Silurian horizons, particularly in fine-grained dolostone associated with the Goat
Island Formation, Lockport Group of New York. It is only occasionally encountered in the Williamsville Waterlime yet
has a wide distribution from southern Ontario, Canada eastward to Syracuse, New York.
Medusaegraptus was originally described as a graptolite, but its algal origin was suspected early on. It is now re-
garded as a dasyclad alga. See, for example: LoDuca, 1990 S.T. LoDuca,
Medusaegraptus mirabilis Ruedemann as
a noncalcified dasyclad alga, Journal of Paleontology 64 (1990) (3), pp. 469–474.
SPECIMEN IS 25 CM IN HEIGHT
ABOVE: A very nice example of
a Late Silurian plant of the type
often referred to as
Cooksonia
sp. Note the well-preserved,
terminal sporangia and what
looks like a rhizome at the
base. Williamsville 'A' Water-
lime, RQS Fort Erie, Canada.
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THE SEARCH GOES ON