01791nas a2200205 4500008004100000245014900041210006900190300001200259490000800271520111500279653001601394653001601410653001301426653001901439653001801458653001701476100001401493700002501507856005301532 2014 eng d00aMonoecious Sycidium, and Other Charophytes, from the Middle Devonian of Eastern New York State, USA, with an Update on the Oldest Bisexual Plant0 aMonoecious Sycidium and Other Charophytes from the Middle Devoni a188-1950 v2003 a

The charophyte flora of the Hamilton Group consists of both vegetative and reproductive organs. The external structure of Sycidium is elucidated by the discovery of antheridial shields at the surface of the utricle containing the oospore. The oldest representative of the genus, the Ludlowian (Upper Silurian) Sycidium siluricum (Ishchenko and Ishchenko) which presents the same complex structure, is thus featured as the oldest bisexual plant. Unknown in North America prior to the Lower Carboniferous, the discovery of Sycidium sp. 1 in the Givetian Hamilton Group provides precise evidence of the distribution of Sycidiaceae during the Middle Devonian. Besides Sycidium, the charophyte assemblage includes gyrogonites and oospores, as well as thallus remains; on the whole, the three orders of Charophyta are represented. The fine grey shales of the Plattekill Formation suggest an aquatic, non-detrital habitat, which was certainly suitable to charophyte vegetation. The preservation of delicate structures reflects an absence of transport during fossilization.

10aBisexuality10aCharophytes10aDevonian10aNew York state10aPalaeoecology10aPreservation1 aFeist, M.1 aVanAller Hernick, L. uhttp://dx.doi.org/10.1016/j.revpalbo.2013.09.007