Fossils of the Paleozoic Era

Topics: Fossil, Trilobite, Extinction event Pages: 9 (2724 words) Published: October 5, 2011
Fossils of the Paleozoic Era

The Earth is thought to be approximately 4.6 billion years old. For years researchers have turned to fossil remains to learn more about the earth and the organisms that have resided here. The history of the earth has been divided in to a widely accepted tine scale in order to make the study of the earths history more organized and understandable. The geologic time scale is used by all kinds of scientist, including geologist, anthropologist, and paleontologist as a way to break down and relate different events to different time spans throughout the history of the earth. The geological time scale is divided into four different sections which are categorized from longest to shortest as followed: Eons, Eras, Periods, and Epochs. Within each Eon is several eras, periods, and Epoch. Within each Era is different periods and epoch. Finally within each period is different epochs.

Spanning roughly 322 years, the Paleozoic Era occupied over half of the Phanerozoic Eon. The Phanerozoic Era, (meaning “time of ancient life”) is extremely significant to the earths history because this is the era that the first “hard” organisms developed. The Paleozoic Era is divided into six geological periods, beginning with the Cambrian period which was approximately 570 million years ago and came to a close at the end of the Permian periods which was approximately 248 million years ago. Other Periods that occurred during this Era included the Ordovician period (492 million years ago), the Silurian Period (435 million years ago), the Devonian Period (412 million years ago), the Lower Carboniferous (Mississippian) Period and Upper Carboniferous (Pennsylvanian) Period (354 million years ago). (Perkins)

Not only did the Paleozoic Era take up a majority of the Phanerozoic Era, but it was also the most diverse era as well. This era was a huge milestone for many organisms including invertebrates, vertebrates, various fish species, tetrapods, reptiles, as well as different plant species. (Kazley)

Scientist study Paleozoic fossils in order to interpret the “paleoenvironmental” conditions of this geological era. A fossil is any remains or evidence of prehistoric life on the earth. The scientific study of prehistoric life by the use of fossils is Paleontology and specific scientist who study fossils are referred to as Paleontologist. There are many different types of fossils including petrified fossils which are formed when small internal pores of the original structure have been filled with precipitated minerals. Trace fossils are evidence of biological activity, this can be footprints, teeth mark, scratches, or even burrows. Replacement fossils form when minerals replace organic content within the organism. Molds are dissolved structures buried in sediments leaving behind the shape of the organism. Casts occur when molds fill with mineral material. Amber fossils are hardened resin of ancient trees, preserving even the most delicate organisms. Fossils can also form by carbonization, which occurs when parts of an organism decompose, leaving behind only carbon, which creates a impression of the organism in rock.

The earliest period within the Paleozoic Era is the Cambrian Period. The Cambrian Period began 570 million years ago and spanned approximately 78 million years. The Cambrian derived from Cambria, which is Roman for Wales, where the rocks from this geological period were originally studied. (Perkins)

“Except enigmatic forms, all modern phyla with a fossil record, except bryozoa, are represented in the Cambrian Period (Perkins) .” Most modern animal groups appeared for the first time in the fossil records during the theoretical time period known as the Cambrian Explosion.

The theory of the Cambrian explosion suggest that around 545 million years ago, a diverse explosion of the development of a giant number of complex, multi-celled organisms. Furthermore, this eruption of animals led to every extant Phylum,...
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