ORDOVICIAN PERIOD The Ordovician Period is the second period of the Paleozoic Era and began 485.4 million years ago and ended 443.4 million years ago (when the Silurian Period began). Four continents were present and separated by three main oceans. Laurentia was composed of present-day North America, part of Scotland, and Greenland and was near the equator. Siberia-Kazakhstan was east of Laurentia, slightly north of the equator. The Iapetus Ocean separated these two masses on the south from the
The mass extinction of Marine-life in the Silurian Period opened up endless possibilities and potential for terrestrial life in the next Geologic time period, The Devonian Period. The Devonian Period served as an introduction to the expansion of the first amphibians, sharks, and some of the first plants with roots, leaves, and stomata. Despite such significant advances, the Devonian Period is best known for its diversity and abundance of underwater life. Not only did fish with cartilage begin to
Oman, this discovery revealed small sea sponges that were alive approximately 635 million years ago.” -Oldest fossil evidence for animals found. Nearing 443 million years ago occurred the third largest extinction in Earth’s history the Ordovician-Silurian extinction, during this extraordinary event almost 85% of all sea life had been wiped out. Preceding this event a giant formation of ice was collecting in the southern hemisphere. It was proposed that this sheet of ice had lowered sea levels and
I. INTRODUCTION A significant portion of New England was formed as a result of an accretionary orogen. Southeastern New England is marked by a series of terranes that accreted onto the Laurentian supercontinent during the Silurian and Devonian. The Terranes of Gander, Nashoba, Avalon, and Meguma are present from west to east in eastern Massachusetts and all of are Gondwanan provenance. Their modern-day juxtaposition suggests that the marginal Gondwanan micro-continents collided sequentially from
First adapt radiation after Ordovician Period was the Silurian period, This happened about 443.7 - 416 years ago and after the first extinction. (N/A,N/A) This was the beginning of fresh water fish, plants and animals left the water to be on land. This began the terrestrial form of life with plant being assigned to the cooksonia genus and the vascular systems of complex plants. this period was subdivided into four epochs which had stages. (Fischer,Liu, Yip, and Yu, 1998) The next period was the
million years and three and a half million years ago. These periods are known as the Silurian and Devonian periods with the Devonian period being commonly known as the age of fishes. The Ostrocoderms was a group of fish that evolved before the Silurian period. These fish have always been described as small fish that had crests on their round heads with an array of spines. The Ostrocoderms are currently extinct. The Silurian period saw the diversification of the Aganthan fish commonly known as the jawless
marine life, sixty percent of the species became extinct due to climatic changes and glaciation. After the Ordovician period is the Silurian period (440-410mya), which is best known for life on land. Once the climate stabilized, land plants grew near the equator and the evolution of fishes began. The first known freshwater fish, and fish with jaws appears. The Silurian strata contains fossils that indicate the previous presence of life during that period. The law of superposition was used to determine
Precambrian Geologic The Precambrian era is about 90% of the earth’s geologic life. It refers to all geologic time before 600 million years ago. During the Precambrian era, the earth formed along with the oceans and atmosphere. Originally, the earth was in a molten state, but as it cooled down, it developed a hard crust and oceans that developed water vapor to form an atmosphere. About five hundred million years after the earth was formed, small continents started to form. The plate tectonics also
A mass extinction or extinction event is the phenomenon in which many species of life on Earth become extinct in a relatively short period of time. Mass extinction refers to an extinction affecting a great many different groups of organisms occupying diverse and wide-spread environments. Extinction of species has occurred throughout the history of life on Earth, but mass extinctions are those events that greatly exceed the normal or background extinction rate. Can mass extinction be inevitable? There
Trilobites Trilobites are extinct sea creatures that were one of the first forms of life on earth. They ruled the world before the time of the dinosaurs, from the Cambrian Period to the Permian Period (between 245 and 600 million years ago). Trilobites are the only extinct form of Arthropods (invertebrate animals having jointed bodies and legs),and were related to the lobster and crab. Their closest living relative today is the horseshoe crab.The name Trilobite refers to it's three lobes
Precambrian Era: The Precambrian Era is when the Earth formed. Earth was barley a spec of dust in outer space and as time went by it gathered ice, rock and more dust particles. It eventually formed into a big rock flying around in space. The Earth was extremely hot and so when it rained the rain would evaporate in mid air or immediately after it hit the ground. But even though it evaporated these great rains cooled the Earth eventually building up water in lower areas creating oceans. The Earths
A Look into the Past Depositional conditions and structural deformation The Austin Glen formation, which may be found at the Johnson Iorio Memorial Park, encompasses an abundance of clastic sedimentary rocks. More specifically, thin black shale and thick greywacke compose this formation. The thin black shale may be described as fine-grained and its color derives from lack of oxidation. This indicates the rock formed in deep ocean conditions. The shale layers are thin, and are approximately
2. A stromatolite is a fossil of blue green algae, or cyanobacteria. They date back up to 3.5 billion years ago, and made other life possible by transforming earth’s atmosphere to one much more suited for terrestrial life, by creating oxygen gas. 3. Archean life was extremely basic, essentially making it harder for anything to go wrong with it. Life first appeared in an incredibly hostile environment, todays earth is much more hospitable and abundant with all sorts of life. 4. The Paleozoic era
biozones than the former (Boardman, 1983). Also interesting about the conodonts origination rates is that the rates were only higher that extinction rates for two periods of time, first at their origination in the Cambrian, and second in the late Silurian right before the Devonian (Clark, 1983) [Figure ?]. However, the key to the conodont extinction is that at the Frasnian-Famennian boundary the biggest discrepancy between the origination rate and extinction rate existed. This gap between rates
swimming, there aren't many who have been around as long, survived as well, or come in so many shapes and kinds as the shark. The earliest evidences of sharks are isolated spines, teeth and scales that appeared about 430 million years ago in the Silurian Period, known as the "Age of Fishes". Sharks have a sleek, streamlined design which helps them swim without using up a lot of energy.They certainly need to conserve their energy because they never really sleep and most of them never stop swimming
Evolution Most botanists believe that the Pteridophytes also known as ferns are descendants of the Rhyniopsida, an extinct group of free-sporing plants which originated in the Silurian period (about 430 million years ago) and went extinct in the mid-Devonian period (about 370 million years ago). Physiology Ferns has no flowers, no seeds, and no fruits. A fern is defined as a cryptogam which means a plant that has no true flowers or seeds. With sporangia, a receptacle in which asexual spores are
lack of igneous rock in area, the sediments from primary igneous rock upstream have weathered and been carried downstream onto the river banks. This process has been accelerated due to the water in the ecosystem. Sedimentary rock from the older Silurian Period is further from the river banks (Geological map of Victoria, 1973). Mudstone, inter-bedded shale and greywacke depositions indicate the Maribyrnong River may have previously taken a different shape, and younger sediments have replaced the
org/stream/starvedrockstate00saue/starvedrockstate00saue_djvu.txt Illinois State Geological Survey, 2005, Time Talks – The Geology of Starved Rock and Matthiessen State Parks Mikculic, D. G., Sargent, M. L., Norby, R. D., and Kolata, D. R., 1985, Silurian Geology of the Des Plaines River Valley, Northeastern Illinois, Illinois State Geological Survey Guidebook 17, 56p.
Introduction Evolving Planet exhibit at the Field Museum of Natural History is a great exhibit that describes the origin of our planet Earth through the evolution theory. This exhibit provides animated and hands-on features to support this theory that our planet originated around 4.5 billion years ago and the history of our planet expanding across several eras and periods attributing to the existence of evolution. Evolving Planet is a vibrant, fun and comprehensive experience with the mission to
Geographical Analysis In this assignment, I will be trying to make an action plan for a change in local environment, and more specifically my home. Now I choose this particular place due to me being so familiarized with it, and looking at the criteria I believe my home could use some help, my home is in the city of Kitchener, Ontario. This city has a unique climate in my opinion as the weather changes between seasons, now many will say that it is normal but they have not seen the amount of change