Abstract Detail



Paleobotany

Gensel, Patricia [1], Stein, William [2], Tomescu, Alexandru [3].

Assessing known plant diversity in the Early Devonian Battery Point Formation.

Some of the first descriptions of Early Devonian plants were by Dawson (1859. 1871) from the Battery Point Formation, Gaspé, with the genus Psilophyton becoming a key indicator of Early Devonian plant complexity.   Many years and studies later, we provide an updated summary and comparison of the composition and diversity of plant taxa from two major Battery Point Formation exposures. Considered as exposed portions of a syncline, the BPF outcrops on the south shore (SS) and on the north shore (NS) of Gaspé Bay; both dip into Gaspé Bay.  The sediments are interpreted as fluvial to alluvial sandstones and mudstones, with a series of sequences of multistory sandstones, single-story sandstones, and mudstones, representing alluvial and some  coastal plain/tidal channel deposits. Most NS plant fossils are more extensively preserved as adpressions with some permineralized (by pyrite) regions, in the mudstones or fine-grained sandstones, while more fragmentary remains occur in the coarser sandstones.  Facies associations were recognized by Hotton et al. (2001).   South shore fossils are preserved as calcareous permineralizations in often large cobbles or calcareous sandstones in a sandstone matrix. Comparing composition of NS and SS assemblages is hampered by differences in preservation (adpression vs permineralization) and degree/extent of preservation (the SS plants being more fragmentary).    Common to both sequences is the genus Psilophyton, although differing at the species level, Spongiophyton, an organism of uncertain affinity (perhaps a lichen), and Prototaxites.    Representatives of Rhyniopsida, Zosterophyllopsida and trimerophyte-grade euphyllophytes occur at both. The pre-lycophyte Drepanophycus, two types of possible gametophytes and one possible hepatic occur in NS sequences, but these are not known, with certainty, from the SS. Unpublished fertile axes from the NS and a stem compression, from higher in the Battery Point Fm on the SS (Stein, pers.com.), may represent cladoxyls or as yet unrecognized lineage(s). These suggest the inception of novel lineages more similar to some Middle Devonian plants, as has been seen among some plants from late Emsian of New Brunswick.   Several plant types remain to be described from both exposures.  Collectively about 26 different plant types are known from these sequences that provide a comprehensive view of early-late Emsian vegetation; some undescribed novel plant types promise to demonstrate the incoming of new lineages toward the end of the Emsian.


1 - University Of North Carolina, Department Of Biology, CB# 3280, Coker Hall, Chapel Hill, NC, 27599, United States
2 - Department Of Biological Sciences, Dept Of Biological Sciences, Suny - Binghamton, Binghamton, NY, 13902, United States
3 - Humboldt State University, Department Of Biological Sciences, 1 Harpst Street, Arcata, CA, 95521, United States

Keywords:
Devonian
plants
Gaspe.

Presentation Type: Oral Paper
Number:
Abstract ID:869
Candidate for Awards:None


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