A North American freshwater sponge (Eospongilla morrisonensis new genus and species) from the Morrison Formation (Upper Jurassic), Colorado
A North American freshwater sponge (Eospongilla morrisonensis new genus and species) from the Morrison Formation (Upper Jurassic), Colorado
复制标题
来自科罗拉多州莫里森组（上侏罗统）的北美淡水海绵（Eospongilla morrisonensis 新属和新种）
作者：
S. Dunagan
玉山始海绵gen.和sp.，最古老的淡水海绵（Demospongea：Spongillidae），发现于上侏罗纪（？Oxfordian/Kimmeridgian to Tithonian）莫里森组，美国科罗拉多州中东部。Eospongilla morrisonensis产于莫里森组发育良好的湖相碳酸盐岩序列中，以两个泥晶体化石为代表，其长180 - 300 μm，直径20 - 35 μm，含方解石替代的巨砾。巨砾是简单的氧化石和圆线虫，缺乏明显的定向作用，可能是由于成岩置换作用。剑形线虫是直的，但圆线虫显示出轻微的弯曲。没有微球;未观察到芽球。
Eospongilla morrisonensis n. gen. and sp., the oldest-described freshwater sponge (Demospongea: Spongillidae), is found in the Upper Jurassic (?Oxfordian/Kimmeridgian to Tithonian) Morrison Formation, east-central Colorado, U.S.A. Eospongilla morrisonensis occurs within the well-developed lacustrine carbonate succession of the Morrison Formation, and is represented by two micritic body fossils with calcite-replaced megascleres that range in length from 180 to 300 μm and in diameter from 20 to 35 μm. Megascleres are simple oxeas and strongyles and lack apparent ornamentation, possibly due to the diagenetic replacement. The oxeas are straight but the strongyles display a slight curvature. Microscleres are absent; gemmoscleres were not observed.