GENSEL, PATRICIA G.1*, MICHELLE E. KOTYK1, WILLIAM H. FORBES2, and GARY BOONE3. 1Dept. Biology, University of North Carolina, Chapel Hill, NC, 27599; 2P.O. Box 447, Washburn, ME 04786; 3136 Canterberry St., Presque Isle, ME 04769. - A newly discovered Devonian plant- bearing locality in northern Maine and a new plant found there.
Within the 30-mile strike-belt of the Fish River Lake Formation, dated
as Middle Ordovician to Early Devonian (Gedinnian) in age, three
recently opened borrow pits within a half mile of one another along
the general strike in low-lying land west of St. Froid Lake disclose a
new assemblage of plant fossils, some of which cannot be recognized as
known taxa. Dispersed spores indicate an age no older than Late Emsian
or early Middle Devonian. Plants are preserved in a light buff
tuffaceous(?) calcareous siltstone located near the contact with the
slates of the Siegenian/Emsian Seboomook Group. This siltstone is
unlike any previously described within the Fish River Lake Formation.
If the Emsian/Eifelian age of the enclosing siltstone becomes more
firmly established through analysis of spores and plants, then this
new fossiliferous sequence must either lie unconformably upon the
older strata, or represent an outlier of a tectonic slide. Impressions
and compressions of a variety of plant types are preserved in these
poorly bedded sediments, including zosterophylls,
Drepanophycus, possible trimerophytes similar to
Psilophyton and Pertica, and new forms. Among the latter
is a very large plant with architecture consisting of a 2 cm wide main
axis that occasionally bifurcates. Both above and below any
bifurcations, numerous densely spiraled lateral branches depart. These
in turn bear decussately arranged ultimate appendages that appear
flattened and slightly laminate and may fork at their tips. Sporangia
are associated with more slender non-laminate appendages borne in the
same position as the former, and appear to be terminal. Comparison to
both cladoxyls and aneurophytes is underway; the distinctive nature of
the ultimate appendages suggests at present that this may represent a
new taxon.
Key words: Devonian plants, new locality, new taxon