branching stems and needle-like leaves of . The plant shows a high degree of development in relation to the age of its fossil remains. Fossils of this plant have been recorded in Australia, Canada, and China. Eohostimella heathana is an early, probably terrestrial, "plant" known from compression fossils of Early Silurian (Llandovery) age. The chemistry of its fossils is similar to that of fossilised vascular plants, rather than algae. The earliest-known animals fully adapted to terrestrial conditions appear during the Mid-Silurian, including the millipede Pneumodesmus. Some evidence also suggests the presence of predatory trigonotarbid arachnoids and myriapods in Late Silurian facies. Predatory invertebrates would indicate that simple food webs were in place that included non-predatory prey animals. Extrapolating back from Early Devonian biota, Andrew Jeram et al. in 1990 suggested a food web based on as-yet-undiscovered detritivores and grazers on micro-organisms. The first bony fish, the Osteichthyes, appeared, represented by the Acanthodians covered with bony scales. Fish reached considerable diversity and developed movable jaws, adapted from the supports of the front two or three gill arches. A diverse fauna of eurypterids (sea scorpions)—some of them several meters in length—prowled the shallow Silurian seas of North America; many of their fossils have been found in New York state. Leeches also made their appearance during the Silurian Period. Brachiopods, bryozoa, molluscs, hederelloids, tentaculitoids, crinoids and trilobites were abundant and diverse. Endobiotic symbionts were common in the corals and stromatoporoids. Reef abundance was patchy; sometimes, fossils are frequent, but at other points, are virtually absent from the rock record. Notes References Emiliani, Cesare. (1992). Planet Earth : Cosmology, Geology, & the Evolution of Life & the Environment. Cambridge University Press. (Paperback Edition ) Mikulic, DG, DEG Briggs, and J Kluessendorf. 1985. A new exceptionally preserved biota from the Lower Silurian of Wisconsin, USA. Philosophical Transactions of the Royal Society of London, 311B:75-86. External links Ogg, Jim (June 2004), Overview of Global Boundary Stratotype Sections and Points (GSSP's) Palaeos: Silurian UCMP Berkeley: The Silurian Paleoportal: Silurian strata in U.S., state by state USGS:Silurian and Devonian Rocks (U.S.) Examples of Silurian Fossils GeoWhen Database for the Silurian Silurian (Chronostratography scale) Geological periods