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HISTORICAL UNIT 4 STUDY GUIDE

THE EON BEGINS WITH THE (Revised 7/18) UNIT 4: VIDEO HIT HOMEWORK; Write a minimum of two paragraphs with minimum of three sentences each for the unit video site

( 1304) (Revised 7//18) UNIT 4 Video Hit For Unit 4 Video Hits, go to the “DMC HOME” website; in Search box –type “Kramer”, select “Faculty Listing”; click on Walter Vernon Kramer, click on Website“, scroll down and click GEOL 1304; then select “Video Hit Link Number 4”, and click on icon. The video is about the .[IF NONE OF THE WEB SITES COME UP, YOUR COMPUTER PROBABLY NEEDS TO BE REBOOTED (RESTARTED)

Introduction - We have reviewed the first 4 BY () of our Earth’s 4.6 BY of existence - We examined the Earth for the Eon, the Eon, and the Eon. - During the Precambrian, we saw continental masses being created - Then plate tectonics really “kicked in” to create and tear apart two - Rodinia and - Earth had two ice ages during this period - Bacteria ruled the Earth for billions of and they created the free for our atmosphere - At the end of the Precambrian, we saw oxygen levels reach 3% - 10% and a few primitive forms in the shallow seas - On a 24 hour “Earth existence clock”, it is now 9:00 PM - The Precambrian Proterozoic Eon was the beginning life eon” - We now enter the last eon – The Phanerozoic (visible life) Eon - With this unit we will examine the Paleozoic (early life) Era of the Phanerozoic Eon - The Paleozoic (early life) Era of the Phanerozoic (visible life) Eon represents almost 50% of the time since the Precambrian (a total of 291 MY).

Determining the Precambrian- Boundary - Original boundary was based on what was thought to be the appearance of the first shelly metazoans. - Date for the beginning of the Cambrian was originally estimated at 590 MY. - Today’s date for the beginning of the Cambrian is about 542 MY.

- Traditionally the Cambrian boundary was picked to represent the appearance of the first body of the Olenellus

- Testing found the original boundary was actually at 525 MY, not 590 MY, so a new boundary had to selected. 1

- In 1991, an international committee selected the Chapel Island Formation at , SE Newfoundland to represent the Cambrian-Precambrian boundary.

- This boundary strata (chosen in 1991) corresponds to the first appearance of distinctive trace and not body fossils. A fossil boundary in that correlated to the Newfoundland boundary was radiometrically age dated at 542 MY.

Early Paleozoic Era (542 MY – 416 MY)

- The Early Paleozoic Era lasted for 126 MY. - It is subdivided into the Cambrian Period, Period, and Period.

Late Paleozoic Era (416 MY – 251 MY)

- The Late Paleozoic Era lasted for 165 MY. - It includes the Period, Period, Period and the Period. - In they use the Period instead of the Mississippian and Pennsylvanian Periods.

Paleographic Maps - One of the goals of historical geology is to provide paleographic reconstructions of early Earth. 2

- The maps can be constructed by synthesizing all of the pertinent paleoclimatic, paleomagnetic, paleontologic, sedimentologic, stratigraphic and tectonic data available. Geography of the Early Paleozoic Era (542 MY – 416 MY) - was one of the 5-6 continental land masses at that time. - Ancestral North America is named . - For most of the Early Paleozoic, would have been found south of the equator. - Only during the Late Paleozoic would Texas again be north of the equator.

Period Maps

- Period maps can sometimes be confusing (used as example maps of the Cambrian) - The maps are interpretations of the geography of an area for a particular time in the geologic past. - All of these maps can be plausible for their exact point in time - The North American continental outlines shown on these maps won’t exist for millions of years - The US and North American outlines are for “reference only” on all the maps

Paleozoic Sea Levels - Eustatic (world-wide) sea levels were higher throughout most of the Paleozoic than the levels of today. - The Paleozoic Era had long periods of no large continental which would equal to a higher sea level. - Rapid sea floor spreading and submarine volcanism can make a significant portion of the sea floor shallower. - Twice during the Paleozoic, there would be extensive continental glaciation which would cause sea levels to drop. - Sea level changes would be most strongly felt over continental land masses. - (Returned to a Cambrian Period map as an example)

- Epicontinental (Epeiric) sea: widespread, shallow seas that transgress or regress over a craton. - This was a common feature of the various periods of the Paleozoic Era, especially over Laurentia (North America).

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- Transgressive: describes a rise in sea level, generally over a craton (left map). - Regressive: describes a fall in sea level, generally off a craton (right map). Transgressive Seas (Using a Cambrian Period map as an example) - Transgressive: describes a rise in sea level, generally over a craton, this would leave behind a stratigraphic sequence.

- This situation (rocks) can provide a record of the rising sea level: sandstone overlain by shales overlain by . - Transgressive sequence: deep-water, sedimentary-rock sequence that overlies shallow-water, sedimentary-rock sequence.

Regressive Seas - Regressive: describes a fall in sea level, generally off a craton; this would leave behind a stratigraphic sequence.

- This situation (rocks) can provide a record of falling sea level: limestone overlain by shale overlain by sandstone. - Regressive sequence: shallow-water sedimentary-rock sequence that overlies deep-water, sedimentary-rock sequences.

FYI: Walther’s Law: can be used to identify transgressions and regressions. - This law states that the sequential vertical changes in sedimentary rock types will equal horizontal sequential changes in rock types.

CAMBRIAN PERIOD (542MY – 488 MY)

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- Epicontinental seas cover a large portion of the North American craton. - On each side of the craton, we can find a transgressive sequence of sediments. - There is no life on land at this time - To the southwest of the craton are a series of islands - Transcontinental arch: a series large, late Cambrian island arcs that extended to southern New Mexico and West Texas (bottom tip of land mass on above map). - Erosion of the craton produced a lot of clean sandstone (good glass sand) in Wisconsin - We can find examples Cambrian sand within the Bliss Sandstone (El Paso area) - We also know that the Enchanted Rock area (Central Texas) had islands because of the Hickory Sandstone (Mason, Texas)

Cambrian Climate - During the Cambrian, the would have been warmer than today - There would not have been advancing glaciers during this time - There would have been no life on land at this time (except bacteria??)

Cambrian Big Bang - At the Cambrian (542 MY), many different life forms suddenly appeared in the fossil record. - This period represents the fundamental mysteries of the on Earth and the fossil record. - For billions of years, life was represented by simple life forms such as bacteria and . - Then for a hundred million years, somewhat complex life forms appeared in the Upper Precambrian Period (630 MY – 542 MY). - There is some recent evidence that a few Ediacaran life forms may have survived beyond the Cambrian 542 MY boundary - Remember that this 542 MY boundary is based on trace fossils and the appearance of “small shelly ” (advanced life) - In 1993 Early Cambrian fossils were been found at Yakutat, Siberia that might be older than (or before) the first Cambrian trace fossils. . The fossils found here were primitive ancestors to sponges, mollusks and .

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Complex Life Forms - The Cambrian Big Bang continued with the rather sudden appearance of other diversified shelly metazoans. - For the first time, complex appeared with protective shells. - New included: legs, claws, antennas, other appendages, eyes and with teeth. - All of these changes can be attributed to - Adaptive radiation: rapid of a single or a few to fill any - This is an evolutionary process derived by and . - Probably environmental changes with genetic change that could survive in the new environment

Environmental Changes Driving the Cambrian Adaptive Radiation 1 - Continued continental breakup allows more shallow water habitats to develop. 2 - Oxygen levels need to reach a critical level. - A certain oxygen level is required to aerate tissues and to make structural components like teeth and . 3 - Evolution of predators would favor prey species that have protective shells. 4 - Chemistry of the oceanic water may have changed to favor the precipitation of calcareous shells. - Most of the ’s iron had been removed and placed into banded iron formations. - Dolomite supply and deposition decreased. - More dissolved oxygen in the water column 5 - Widespread submarine volcanism increased availability of energy and nutrients.

Genetic Causes of Cambrian Adaptive Radiation - The various forms of drive the process of evolving organisms that survive the changing environments.

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Chengjiang - The best Early Cambrian fossils are found in China - In 1984, a large number of diverse Early Cambrian fossils were discovered here. - The fossils here are really complex considering that complex life is just beginning on Earth. - This implies that the may have occurred in as little as 10 MY.

- (Video clip of life in the Cambrian Chinese sea)

Sirius Passet, - Also in 1984, fossils were discovered here which have the same age as fossils found in China

Burgess Shale Biota - No discussion of Cambrian life is complete without discussing the Middle Cambrian Burgess Shale biota. You can visit the site: 12 mile walk, 11 hour trip, 3,000 elevation change, $100 fee. - The Burges Shale was discovered in 1909 near Field, British Columbia, Canada - This Middle Cambrian shale (515 – 520 MY) contains some of the best period examples of soft bodied flora and fauna known. - The shale provides fossil examples of Earth’s first complex animals. - These animals had shells, heads, mouths, eyes, claws, legs and other appendages - Many animals of the Burgess shale are “unknown phyla” - have no living organisms with their basic . - This biota of represents the root stock and basic body parts from all present day invertebrates (and ). - Life was much more diverse in terms of phyla during the Cambrian than today. - The biota here suggests the Cambrian big bang or explosion occurred over a relatively short period of geologic time.

Life Body Plans - The pattern for the rest of the history of life was set in the Cambrian Period (542 MY – 488 MY). - By the end of the Cambrian, ancestors of all living phyla of shelly invertebrates had appeared (except bryozoans). - No new shelly phyla have appeared since that time. - The Early and Middle Cambrian fossils seem to imply early experimentation and then later standardization.

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Phylum Chordata - All are bilateral animals related by possessing : something resembling a backbone - A notochord (spinal chord) will eventually evolve into a backbone

Earliest Known - diadexus age is 535 MY from China - The chordate Yunnanozoon, figure 21.15, page 554 of text, has been reassigned to Hemichordata.

- Next oldest known chordate (not ) found at the Burgess Shale, at 520 MY, is the 2-3 inch , a (above).

Oldest Known Vertebrate - Vertebrates: animals with backbones (covered notochord) - Earliest known vertebrates are . - is one of two of the oldest known vertebrate fish at 530 MY, found at Chengjiang, China. - Haikouichths is also found at 530 MY

- (Video clip of Cambrian fish)

Trilobites - Cambrian is also known as the Age of the - All orders of trilobites would evolve in the Cambrian - Trilobites would make up +50% of the Cambrian fauna (542 MY – 488 MY). - There would be more than 20,000 species (as you can see from www.Trilobites.info website) - The trilobites would have a wide variety of eye types. - Trilobites are the world’s most popular fossil to collect. - Trilobites would roll themselves up when faced with danger. - Quite a few trilobites can be found near Llano, Brownwood and El Paso, Texas. - Present day sow bugs and horse shoe crabs are not related to trilobites.

End of Cambrian - The end of the Cambrian would be marked by colder temperatures and mass of most of the trilobites

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Ordovician Period (488 MY – 444 MY) - As during the Precambrian, ancestral North America will again be subjected to tectonic forces and many colliding land masses - Such a tectonic collision is called an orogeny - Orogeny: an episode of mountain building, usually associated with convergent zones. - The results of an orogeny is intense crustal deformation accompanied by metamorphism and igneous intrusions and thickening of the Earth’s crust. - This is directly associated with colliding tectonic plates at convergent plate boundaries or subduction zones - (Mountains form along convergent zones.)

Taconic Orogeny of the (oldest) - At 510 MY (Cambrian), the eastern US continental shoreline extended from New York to the Carolinas - During the Ordovician, Laurentia would remain south of today’s equator. - Before this event, the Eastern US shoreline extended only from the Carolinas to New York. - Offshore, an island arc called the Taconic Arch is headed toward Laurentia during the Early Ordovician - The Taconic Island Arc would first collide with the Canadian Maritime provinces - The arc finished its collision (convergence) by 450 MY, extending the US coastline from New to Georgia. - Remember that with convergent (subduction) zones, we find related igneous intrusions and the Taconic Orogeny is no different - The igneous intrusions from Georgia to New York all have similar age-dating of intrusions -460 to 440 MY (Taconic Orogeny). - Later, two large masses begin approaching Laurentia from the eastern coast of the – the continent of and the Islands (Acadian Orogeny) - But we will have to wait for the Devonian for the US collision - The early Appalachian Mountains created by the Taconic Orogeny will erode downwards before the Acadian Orogeny - Why is it that, over time, most mountains do not erode to a totally flat sea level plane? - Mountains are characterized as rising above surrounding area; for this to happen, mountains must have deep roots - Mountains and mountain roots are a property of isostasy.

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- Isostasy: the concept of the Earth’s crust floating on a dense underlying layer. - This concept can be illustrated by a cork in floating water. - As mountains erode, isostatic adjustments push the mountain roots upward. - Isostatic rebound: the phenomena in which unloading (erosion) of the crust (mountains) causes the crust to rise until it attains equilibrium. - Thus older mountains will always be higher than the surrounding plains - This is why mountains persist over millions of years.

- Ordovician sea levels were very high with transgressive seas over the North American craton, until the end of the period - The (Appalachian) Taconic Highlands now begin to erode downwards - Thick sediments were deposited opposite the eastern subduction zone - This would create the Queenstown Clastic Wedge

West Texas - In the Early Ordovician, a large deposit of sand-grained filled dolostone (dolomite) was deposited by the seas, called the sandy El Paso Formation in the El Paso area. - In the Middle Ordovician, large deposits of dolostone (dolomite) were deposited by advancing seas, called the Montoya Formation in the El Paso area. - East of the El Paso area is found the Lower Ordovician Ellenberger Formation – a deep, thick dolomite that has an associated 90 large oil fields and 50 major gas fields. Outcrops can be found near Llano Texas.

Marine Life in the Ordovician - mollusks grew to more than 18 feet in length. - Brachiopods (resembles clams) would increase in importance. - Some trilobites survived into the Ordovician - would become well established in the seas

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Class – Fish of the Ordovician - These are jawless fish that became common during the Ordovician Period - These are some of the most primitive fish - they lack a , paired and gut instead of stomach. - There were six major groups called including Ostracoderms, a bony-skin fish that was about 10 inches long and lived only from the Cambrian to the Devonian (542 MY – 416 MY). - Modern day examples include and

Ordovician Land Plants - There is some evidence that primitive algae and lichens invaded the land masses

An Ordovician Ice Age and a Mass Extinction - The third extensive continental glaciation will occur at the end of the Ordovician Period - This will cause sea levels to drop (regressive seas) - The glaciation also lowered water - The temperature and sea level drops will have a catastrophic effect on life; this probably led to the mass extinction of many life forms. - About 12% of Earth’s life forms would become extinct. - Most of the occurred in shallow tropical waters - This would include more than 100 families of . - There were basically no land forms of life yet.

Silurian Period (444 MY – 416 MY) - Ancestral North America will soon again be subjected to tectonics by an approaching land mass - Two other large land masses began approaching Laurentia from the western coast of the Iapetus Ocean – the continent of Baltica and the islands of Avalonia - Let’s begin the process at 450 MY in which the plates are approaching one another - Baltica has collided with Canada and Avalonia is headed toward the eastern coast of the US 11

- But Avalonia will not yet collide with the US during the Silurian Period - Meanwhile, the earlier Appalachian Mountains by the Taconic Orogeny are beginning to erode downwards

Silurian Seas and Deposition - Another period of high sea levels (transgressive seas) will cover most of North America (Laurentia). - In the Michigan basin, large reefs would block seawater, resulting in thick salt deposits within the Michigan basin. - In Texas, large deposits of sandy dolomite (El Paso area) were deposited by the seas, called the Fusselman Dolomite. - To the east of El Paso, the Fusselman Dolomite is a major oil and gas producer in the deep wells of West Texas.

Silurian Fish - Sea life would now be filling as many niches as possible and we even have fish - Silurian fish will take a major evolutionary step forward - To develop further, fish needed to develop a jaw. - Some suggest that the vertebrate jaw began with modifications of the first 2 or 3 arches. - The first fish with would develop during the Silurian Period - Acanthodii were the first fish with jaws, known as spiny fish that grew up to 6 feet in length. - Lived from Silurian to the end of the Paleozoic (444 MY – 251 MY). 12

- Class is a monstrous Silurian armored fish that became extinct after only 50 million years of existence. - Group Arthrodires: was a giant predator that grew more than 20 feet long and had a giant head. - Group Antiarchs: grew up to two (2) feet long and had over 100 species.

Insects - The Silurian saw the development of large sea scorpions up to three feet long - (Video clip of jawless fish and large sea scorpions)

- Later sea scorpions up to 10 feet long would evolve - (Video clip of a giant sea scorpion)

First Invasion of Life on Land - Even with the transgressive seas, there would be enough land available for life to invade - Before there can be animal life on the land, there must be some kind of a food supply for them - The first invasion of living organisms would take place during the Silurian - And this occur about 430 MY ago by algae and vascular plants. - Earliest known vascular is Psilopsids - (Video clip of Silurian plants)

Insects () - The earliest animals on land would be insects - Oldest known fossil is the millipede (Silurian Age); we have found fossil footprints of some giant millipedes. - Also, there were many bizarre giant, scorpion-like insects that invaded the shorelines. - (Video clip of scorpions on land)

Age of - The Silurian Period is often called the Age of the Corals because of the great abundance

End of Silurian Period - The end of the Silurian Period is marked by a few groups of small marine creatures becoming extinct

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Devonian Period (416 MT – 359 MY) - We are now moving to the Late Paleozoic - Life and Earth will undergo some major changes during this period - The components for the Acadian Orogeny started at 450 MY (Ordovician) in which the plates of Laurentia and Baltica and the island arc of Avalonia are converging - The early Appalachian Mountains created by the Taconic Orogeny have eroded downwards (Ordovician – Silurian) - Baltica had converged with Canada and Avalonia was converging toward the eastern US coast (Silurian)

- The final convergence of the Acadian Orogeny created a very tall Appalachian Mountains in the Devonian Period - Now we have the second generation Appalachian Mountains

Determining Ages of Mountains - There are three different methods used to give the age of mountains - 1) Age of mountains determined by the age of the rock deposition - This is the time that the rocks actually formed but we have a problem: What if the deposition covered several ages? Do you use the latest age? - 2) Age of mountains determined by the orogeny that formed the mountains - This represents the timing of the orogeny event. What if there was more than one orogeny? - 3) Age of the mountains as determined by the topography - What if the present topography was created by a renewed uplift? - One or all three methods have been used to age-date a mountain

Antler Orogeny of Western US - What else is going on that would eventually converge with Laurentia during the Devonian - The Antler Highland mini-continent has been moving toward Laurentia - But this Antler Orogeny will not occur until the end of the Devonian

Gold and the Antler Highland - This ancient landmass forms a greater portion of the outcropping rocks of the state of Nevada. - Some of the largest and richest US gold mining districts are found within this ancient Antler Highland

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Euramerica - There is now a larger landmass created by the Taconic, Acadian and Antler orogenies - We would now have a new huge continent called Euramerica (or )

The Devonian Seas and Potash - We will have mostly transgressive seas during the Devonian along with some times of regression - Only a thin layer of Devonian rocks is found in Texas, the Canutillo Limestone in the El Paso area. - Reefs blocked off most of the seawater from the in Canada which is the site of large salt and world class potash deposits. (Potash is used for fertilizer)

Plants - Land plants become widespread, large and diversified - first began along the river banks with shallow roots - This will provide even more food for more animals to invade the lands - Finally, tall (seed-bearing gymnosperms) with deep roots will evolve toward the end of the Devonian - Earth is becoming slightly more familiar

Life in the Devonian Seas - There will still be a few trilobite species in the seas - Major changes were occurring in the shallow Devonian Sea especially with fish - The Devonian Period is also known as the Age of the Fish - All five (5) classes of fish would be alive at this time and there would be no new classes. - Before we continue the lobe-finned fish, let’s review some of the fish that we have studied up to now: acanthodians and Placodermi - Let’s examine Devonian cartilaginous fish - Class includes all of the cartilaginous fish (, rays, etc.) - This class includes a number of extinct but very weird shaped sharks including: , Heliocoprion, Scissor- , and Farukatasu - (Video clip of sharks and big fish) -Let’s examine the remaining fish types that evolved during the Devonian - Class (bony fish) have two types of bony fish: lobe-finned fish and ray-finned fish - Crossopterygii includes the lobe-finned , that first appeared in the Devonian and was thought to be extinct 75 MY ago; but was rediscovered as a living fish in 1938. - We can see some evolutionary changes with the lobe-finned fish

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- They have articulated within stubby fins. - They have muscles that extend into the fins. - This is important because this would be the beginning of limbs.

- Tetra is Greek for four and Podos is Greek for foot - Tetrapod: Vertebrate animals having 4 feet or leg-like appendages (excludes fish) - A is with the Order Dipnoi that was first seen in the Devonian. - This is a that took another evolutionary step forward with external nostrils and lungs as well as - Lungfish have articulated bones in fins with muscles in the fins - This includes the Devonian (416 MY – 359 MY) that had long frontal lobe-fins - Let’s examine a that some scientists had earlier thought was the first tetrapod ancestor of (found in the Devonian Period) - Acanthostega at one time was thought to be an . But they probably had no lungs – just gills like fish.

- Let’s also examine a present day tetrapod-like fish – the of today - “Mudskippers” are examples of modern day tetrapod fish (front limbs more developed than rear). - (Video of a battle) - Other lobe-finned fish in the Devonian were showing their presence and may have been feeding onshore - It is suspected that fed out of the water along shoreline. - Recent discovery of an air-breathing fish with front legs has been hailed as the missing link to amphibians – roseae

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- Why do we suspect that fish may have walked on land? - From a shallow water basin, we find +365 MY something large was walking in shallow water with their widely separated footprints, preserved in today’s rocks. - (Video clip of a Eusthenopteron)

- The first tetrapod ancestors of amphibians is found in the Devonian Period - The labyrinthodonts called had seven toes on its back fins (feet). - We reviewed how the original fins of various creatures as they rapidly evolved into feet - (Video showing possible into amphibians)

- At the end of the Devonian, another mass extinction would affect about 14% of Earth’s life forms. - This resulted in the near collapse of all massive reef communities and one class of fish. - Almost all warm water environments were affected but not the cool water environments. - The primitive land plants were not affected by this event. - The Devonian mass extinction may have taken a few million years to complete - Causes: global cooling? Oceanic volcanoes? Other?

Mississippian Period (359 MY – 318 MY)

- Earth is preparing for its largest collision ever. - Now at 327 MY, Euramerica (Laurasia) is headed toward which will produce the 17

- With this convergence, we will suture these masses together - In the next period, tectonics will create the third generation of the Appalachian Mountains when will converge here - The Mississippian Period is the last very widespread transgressive epicontinental sea. - Many parts of “North America” will be covered by vast shale deposits - We are not sure why so much mud was deposited here

- The Barnett Formation of Central and West Texas is one of such shale deposit - Oil and gas wells are widespread within the Bartlett Shale. Horizontal drilling and fracking became big business for the first time here. - These wells will contribute +$100 Billion to the Texas economy

- Although the Mississippian is part of the “Carboniferous Period”, very little is associated with this age in the US - The epicontinental seas will contain abundant forms of life. - The Mississippian is also called the Age of the (sea lilies) - Blastoids (a type of sea lily) became very common

- We know that amphibians were walking near water at this time - 350 MY Mississippian footprints (probable amphibian) have been found in Canada. - Amphibians had a major problem in that they had to lay gelatinous eggs in water. - The next evolutionary step for vertebrates will be the development of the amniotic egg. - These amniotic eggs (whether hatched inside the mother or in nests on the ground) provide the parents () greater opportunity for expanding their environment. - (Video of the transformation of eggs)

- The first suspected is a small -like (350 MY) in - Although we find a possible reptile here, the real “Age of the Reptiles” is the Permian Period (299 MY – 251 MY and different than the Age of ). - The step from amphibian to reptile would take less than 60 MY

- At the end of the Mississippian Period, CO2 levels dropped from 1800 ppm to 300 ppm and world temperatures dropped - The Mississippian Period would end with a minor extinction of a few sea creatures

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Pennsylvania Period (318 MY – 299 MY)

- This is the period of the “big collision” - We will begin with the Allegheny Orogeny - Now the latest Appalachian Mountains are part of the supercontinent Pangaea (Pennsylvanian- Permian Periods) - It will be Permian times before the convergence with Africa will end

- Meanwhile, is converging with North America – the - The results include the formation of the of Arkansas and Oklahoma - During the Allegheny Orogeny, the Llano area of central Texas will be uplifted from great depths

- Epicontinental seas are still present but less extensive than previous periods. - These regressive seas will expose a series of islands in the western US - The formation of Pangaea is nearly complete. - Major coal deposits would form in the Eastern US and Texas. 19

- Evaporation would cause thick salt and potash deposits in New Mexico and Utah. - Outcrops of Pennsylvanian limestone can be found in north-central Texas.

- During the Pennsylvanian Period, the craton (North America) would be part of Pangaea - The Appalachians, Ouachita and Antler Mountains are present - Major swamps are located along the equator, which will become vast coal deposits - Even Texas has vast coal resources from these swamps - (Video about the coal swamps)

- Trapped seas would collect in the basins - Large deposits of potash would be created in New Mexico and Utah

- With a large land mass and ongoing evolution near the equator, some changes are going on - The first undisputed reptile is a small lizard-like that has been found in the 300 MY (Pennsylvanian) Formation, Nova Scotia in Canada.

- The first -like animals will appear now; we will discuss mammal-like in the Permian Period - The Pennsylvanian Period is also known as the Age of Plants and Age of Giant Insects. - New evidence suggests that insects may have developed in the Devonian Period - Winged insects are common in the Pennsylvanian Period - Dragonflies became giants, some with wingspans of 36 inches - This period could also be called the Age of the Cockroaches since more than a thousand species were present and they grew to be giants - (video about insects – spiders, dragonflies, and centipedes)

- Earth will enter its fourth ice age at the end of the Pennsylvanian Period - This will cause a minor extension with some marine fauna

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Permian Period (299 MY – 251 MT)

- The Allegheny Orogeny will be completed and we now have the supercontinent of Pangaea - And the Appalachian-Caledonian Mountain ranges were created - For half of the Permian Period, Earth will endure its fourth ice age- Fewer swamps will be around for most of the Permian - Glaciers and deserts are common for most of this period - There were fewer transgressive seas - And the Appalachian- Caledonian Mountains will present a barrier for - During this period, only the western 1/3 of the US was under shallow seas.

- In West Texas, there is a large evaporate basin - In this basin, the thick Castile Gypsum will be deposited

- The West Texas Permian Basins would be inland seas with the seawater coming from the west - Large reefs (shelves) would surround these seas - El Capitan in the Guadalupe Mountains is actually a world famous Permian reef. - The Permian Basin is famous for its huge oil and gas deposits and has produced 15 billion barrels oil.

- In the Utah area is the Phosphoric Sea where valuable deposits of phosphates (fertilizer) will be deposited. - There are extensive Permian deposits of sandstone and limestone in North-central Texas.

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- Animal life expanded on the lands

- Large primitive amphibians lived along the shorelines of Texas: - Seymouria baylorensis, from Baylor County, (North) Texas - and from Archer County, (North) Texas - from near Abilene, Taylor County, Texas is a famous Texas fossil.

- We should mention the freshwater reptile mesosaurs of African and South American rivers

- The Permian Period is also known as the Age of the Mammal-like Reptiles (not dinosaurs) - And we will see that at the end of the Permian – this will be a failed life form for Earth - The finned-back are mammal-like reptiles - This includes the carnivorous and an herbivore - Dimetrodon skeletons have been found Archer County, North Texas. - (Video on big reptiles and video on mammal-like reptile) - What do we mean by mammal like? - The mammal-like animals had several mammalian skeletal characteristics” - Primitive differentiation of teeth, like (all other animals have same style teeth) - They have several mammalian skeletal characteristics. - No true mammals have been found before the Era. - (Video on teeth) - Now the therapsids will evolve - (Video – Late Permian) - The world environments become largely deserts - (Two videos on changes) - The end of the Permian Period would result in the largest mass ever recorded on Earth - (Video clip) EXTINCTIONS

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Late Ordovician (444 MY) Mass Extinction - There were times when Earth was not a very friendly place for many forms of life. - At the late Ordovician, about 12% of Earth’s life forms would become extinct. - This would include more than 100 families of marine invertebrates. - There were basically no land forms of life yet.

Late Devonian (359 MY) Mass Extinction - At the end of the Devonian, another mass extinction would affect about 14% of Earth’s life forms. - This resulted in the near collapse of all massive reef communities and one class of fish. - Almost all warm water environments were affected but not the cool water environments. - The primitive land plants were not affected by this event.

Late Permian (251 MY) Mass Extinction - This event would mark the largest mass extinction event ever recorded on Earth. - More than 52% of Earth’s “families” became extinct. - This event marks the end of the Permian Period and Paleozoic Era.

Permian Life Forms That Became Extinct by 251 MY Ago - 90% -95% of all marine species died out (shallow water). - Only one of the many species of Crinoids survived (shallow water). - All blastoids disappeared (shallow water). - 80% of all brachiopods disappeared (shallow water). - Almost all gastropods (sea snails) disappeared (shallow water). - 8 out of 27 orders of insects disappeared (land environment). - Two orders of disappeared (shallow water). - 75% of all reptiles disappeared (land environment) - 67% of all amphibians disappeared (water and land environments) - Another entire class of fish disappeared (marine environment) - All trilobites disappeared (all water environments).

Timing of the Permian Period Mass Extinction - This extinction was not instantaneous but occurred over a period of less than 800,000 years - Succeeding Mesozoic life forms would have a very low diversity but the surviving species would tend to be very abundant and widespread.

Probable Cause of the Permian Mass Extinction - We do not know for certain.

Types of Extinctions - Extinction: the planet-wide disappearance of a species or higher taxonomic group. - This is the ultimate fate of all species. - This is a continuous process as recorded in the fossil records. - Looking back at the Phanerozoic Era, we have noticed five severe mass extinctions. - Background Extinctions: continued extinction of species. - Mass Extinctions: twice the background rate - Minor Mass Extinction: same as above (mass extinction); a good example would be the decrease in many species at the end of the last Ice Age.

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Time to Complete A Mass Extinction - From a few months to a few million years.

Significance of a Mass Extinction - This signifies a planet-wide environmental or ecological problem. - For one species, a mass extinction is bad but for another species – a mass extinction of their competitors is good. - The extinction of a large number of dominant species is instrumental in the expansion of “minor” species to fill the niche left open by the mass extinction.

Theories of Mass Extinctions - Most are related to catastrophic changes in the atmosphere; or - Catastrophic changes in the hydrosphere - Many geologic events can severely affect either one or both of these spheres.

Meteorite Impacts - These can have a major impact on Earth’s atmosphere, with the addition of gas, dust and chemicals. - The hydrosphere and atmosphere could be severely impacted by sudden global heating and global cooling.

Related to Massive Volcanism -Flood basalts: huge flows (thousand of cubic miles) of basalt from fissures. - These add huge quantities of greenhouse methane and CO2 gases to the atmosphere

Continental Glaciation - This can cause major changes in sea levels that affect cooler ocean water and world temperatures.

Tectonics - The formation of a super-continent can cause major changes in ocean currents and on climate.

Others - Also postulated are problems with magnetic reversals and supernovas. - However, there has never been a total extinction during the Phanerozoic Eon.

END OF UNIT 6

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