LATE PALEOZOIC PALEOBOTANY OF TEXAS - A PALEOECOLOGIC EXAMINATION

The sediments of non-marine and island paleoenvironments in Texas have produced a wealth of information regarding the evolution and community response to changing conditions in a relatively unbroken record from the Upper Pennsylvanian to the earliest Middle Permian; no fossil plants have been recovered from Upper Permian strata. All recorded environments in Texas are equatorial and near sea level. An overall drying trend is recorded in both the sedimentologic and paleobotanical records, with coal in the late Pennsylvanian and evaporites in the upper part of the Lower Permian into the Middle Permian. The paleosol record supports this trend and adds considerable detail. Spore-producing species dominate during the ever-wet periods and in wetter habitats during seasonally dry periods. Seed-ferns and conifers dominate during more seasonally dry times. An unusual flora with strong Mesozoic affinities occurs in late Lower Permian strata deposited under seasonally wet to arid conditions. The Island flora may range through the Lower Permian; it is of low diversity and uniform composition throughout its wide geographic distribution, reflecting adaptation to growth under stressful near shore conditions. This temporal and spatial floristic and environmental record represents a baseline against which Lower Permian floras from other western states can be compared, forming a transect across a landscape from sea shore to mountain front.