Cenozoic mammals 107 [Illustration: Plate 1 GEOLOGIC TIME SCALE] ERA PERIOD EPOCH CHARACTERISTIC LIFE CENOZOIC “Recent Life” QUATERNARY 1 MILLION YEARS Recent Pleistocene TERTIARY 64 MILLION YEARS Pliocene Miocene Oligocene Eocene Paleocene MESOZOIC “Middle Life” CRETACEOUS 70 MILLION YEARS JURASSIC 45 MILLION YEARS TRIASSIC 50 MILLION YEARS PALEOZOIC “Ancient Life” PERMIAN 55 MILLION YEARS CARBONIFEROUS PENNSYLVANIAN 30 MILLION YEARS MISSISSIPPIAN 35 MILLION YEARS DEVONIAN 55 MILLION YEARS SILURIAN 20 MILLION YEARS ORDOVICIAN 75 MILLION YEARS CAMBRIAN 100 MILLION YEARS PRECAMBRIAN ERAS PROTEROZOIC ERA ARCHEOZOIC ERA APPROXIMATE AGE OF THE EARTH MORE THAN 3 BILLION 300 MILLION YEARS Texas Fossils An Amateur Collector’s Handbook William H. Matthews III[1] INTRODUCTION Almost everyone has seen the fossilized remains of prehistoric plants or animals. These might have been the skeleton of a gigantic dinosaur, the petrified trunk of an ancient tree, or the shells of snails or oysters that lived in the great seas that covered Texas millions of years ago. Each year more and more people are learning that these fossils are more than mere curiosities. Instead, they are realizing that a good collection of fossils provides much information about the early history of our earth, and that fossil collecting can be a most enjoyable, fascinating, and rewarding hobby. It is for these people that _Texas Fossils_ was written. This publication is primarily an amateur collector’s handbook and as such offers many suggestions and aids to those who would pursue the hobby of fossil collecting. It tells, for example, what fossils are, where and how to collect them, and how they are used. Suggestions are made as to how the specimens may be identified and catalogued, and there are discussions and illustrations of the main types of plant and animal fossils. Included also is a simplified geologic map of Texas and a brief review of the geology of the State.