HOME / NEXT / PREVIOUS / EQUIPMENT / MAPS / FOSSIL SITES / OK FOSSILS
The Silurian period lasts from about 440 to 410 mya. It is a relatively short period in geological history, but many important discoveries have been made concerning this period. This was a time of stabilization of global temperatures as well as a time when evidence of the first terrestrial animals and freshwater fish have been recorded.
Oklahoma was still an underwater environment during the Silurian. Silurian limestones in the state can be found exposed in the western Wichita uplifts and in the northeastern Ozark uplift near Tulsa. Other Ordovician/Silurian/Devonian rocks can be found exposed in the Arbuckle and Ouachita uplifts.
Locations of Silurian Landmasses
From the PaleoMap Project
The most predominant organisms during the Silurian were the hard-shelled Braciopods. It is estimated that these creatures made up about 80% of the total species at the time. Tropical Reefs were common in the shallow seas with Corals, Stromatoporid organisms, and Bryoza being most common. Trilobites, Graptolites, Cephalopds, Gastropods, and Echinoderms will still evident however the Trilobites were still in a period of decline. During this period the Graptolites also began declining in numbers.
The Silurian period is the first period in history where fish begin to appear in the fossil record. At the beginning of the period, jawless fishes appeared to have invaded the freshwaters while at the end of the period, jawed fishes begin to appear. These animals were not considered to be the dominant creatures however.
Another major occurence during the Silurian is the appearance of the first terrestrial ecosystem. The first evidence of vascular plants (plants with tissues that carry food) appear in the fossil record of areas above sea level. The earliest land plant and possible millipede-like animal fossils were found in modern day Europe.
TO THE DEVONIAN...