RECONSTRUCTION OF A CYATHIFORM EUGONOPHYLLUM - UPPER PENNSYLVANIAN, PALO-PINTO COUNTY, TEXAS

Species of Eugonophyllum (Codiaceae, Chlorophyta) have traditionally b een characterized as phylloid or leaf-like. But a reconstruction of we ll preserved specimens of Eugonophyllum, probably E. johnsonii Konishi and Wray, from Upper Pennsylvanian limestone formations of Pale Pinto County, Texas, indicates it was cyathiform or cup-shaped. Reconstruct ion was based on the forms of membranes as seen in sections and on par tial excavation of thalli. This Eugonophyllum shared with congeneric s pecies of Eugonophyllum the characteristic two-layered cortex (outer a nd inner), and with other codiaceans the same general membrane structu re consisting of bilateral cortices with palisades of utricles now fil led with micrite, and a medulla of tubular coenocytes, an area now mos tly filled with mosaic sparry calcite. A cyathiform thallus would have inner and outer cortices but no differences were found in the structu re of the inner and outer cortical utricular casts. The thalli were ap parently anchored with elongated, cylindrical holdfasts. Internal sphe rical structures, presumably developed from differentiated utricles, m ay have been zygotes or young embryos from an oogamous fertilization. These were apparently released to the environment through the membrane .