Chu, Jessica , Tomescu, Alexandru M.F. .
Reappraising the flora of the Battery Point Formation (Québec) – additional diversity of Early Devonian permineralized plants.
Early Devonian plants record the early stages of the initial tracheophyte radiation and are central to understanding the origins of major vascular plant lineages. Although Early Devonian plants are known worldwide, occurrences of anatomical preservation are rare for this interval. One such occurrence is the Battery Point Formation, a unit exposed on the Gaspé Peninsula (Québec), which hosts abundant Emsian plants preserved as compressions and permineralizations (anatomical preservation). However, while the compression flora of the Battery Point Formation has been documented by numerous studies, the anatomically preserved material in this unit has been the object of only a handful of studies, to date. We conducted an exhaustive survey of the diversity of anatomically preserved plants in a set of Battery Point Formation samples, for comparisons with the diversity of compression plants. Previous studies have uncovered a broad taxonomic range of plants preserved as compressions – diverse trimerophytes and zosterophylls, as well as thalloid forms, axial gametophytes, rhyniophytes, and one lycophyte – totaling 19 genera, six of which have yet to be characterized. Three of the compression genera are also found permineralized, while one genus is known only from permineralizations. Our survey of the permineralized flora revealed at least ten distinct taxa (possibly up to 14 or more). Of these, up to three represent genera previously described from this flora as permineralizations, and at least six are new for the Early Devonian. Notable among these are: a type exhibiting extensive secondary growth; one with a large centrarch stele and narrow tracheids; a cladoxylopsid; and a probable aneurophytalean progymnosperm. The latter two are the largest plant taxa recorded to date as permineralizations in the Battery Point Formation and, if confirmed, mark the oldest fossil records of their respective lineages. This raises the possibility that some of the largest plant compressions recorded in the unit represent cladoxylopsids and progymnosperms. Taken together, the diversity of permineralized plants recorded in the Battery Point Formation is approaching that of the compression taxa. Furthermore, the abundance of specimens displaying secondary growth is unexpected for this interval. Overall, the Battery Point Formation is emerging as a key unit for anatomically preserved Early Devonian plants, approaching the diversity of the classic Rhynie chert flora. While the quality of preservation does not match that of the Rhynie chert, the Battery Point Formation offers extensive exposures and easy access, holding excellent potential for future discoveries of additional Early Devonian plant diversity.
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1 - Humboldt State University, Department of Biological Sciences, 1 Harpst St., Arcata, CA, 95521, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Salon 5/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 8:15 AM
Candidate for Awards:Isabel Cookson Award,Maynard F. Moseley Award