EARTH HISTORY UNIT 5 Mesozoic & Cenozoic Eras

HISTORICAL GEOLOGY UNIT 5 LECTURE AND STUDY GUIDE THE MESOZOIC AND CENOZOIC Chapters 22 & 23 (Revised 7/18) UNIT 5: VIDEO HIT HOMEWORK; Write a minimum of two paragraphs with minimum of three sentences each for the unit video site

(HISTORICAL GEOLOGY 1304) (Revised 7//18) UNIT 5 Video Hit For Unit 5 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 5”, and click on icon. The video is about megalodons. [IF NONE OF THE WEB SITES COME UP, YOUR COMPUTER PROBABLY NEEDS TO BE REBOOTED (RESTARTED)

Part 1: Mesozoic Era (Chapter 22)

Eons, Eras and Periods - Phanerozoic Eon is also called the eon of “visible life”. - The Mesozoic Era (Middle Era) spans 251 MY - 65 MY and is considered the Age of the Dinosaurs. - The Mesozoic consists of three periods: - Triassic Period: 251 MY – 200 MY - Jurassic Period: 200 MY – 145 MY - Cretaceous Period: 145 MY – 65 MY

The End of the Paleozoic Era - Let’s recall the end of the Paleozoic Era and the end of the Permian Period. - The end of the Paleozoic Era (Permian Period) marked Earth’s largest mass extinction ever recorded on Earth. - The land plants were basically unaffected. - We reviewed the list of animals that went extinct: - 90% - 95% of all marine invertebrate species died - Only one species of crinoids survived - All blastoids disappeared - 80% of all brachiopods disappeared - Almost all gastropods disappeared - 8 of 27 orders of insects disappeared - Two orders of corals disappeared - 78% of all mammal-like reptile families disappeared - 67% of all amphibian disappeared - Two entire classes of fishes disappeared - All trilobites disappeared - This extinction may not have been instantaneous but occurred over a period of 800,000 years. - Although a lot of individual species survived and multiplied, Earth’s biodiversity would be low - We are now leaving the Permian Period of the Paleozoic Era with the supercontinent of Pangaea intact. - There was an end-of-Permian continental glaciation used by Wegner to define the existence of Pangaea - But before the beginning of the Mesozoic, Earth undergoes a period of global warming and this type of continental glaciation will disappear for the next 250 MY - Also at this time, Pangaea is made up of Laurasia (Laurentia) and Gondwana 1

THE TRIASSIC PERIOD OF THE MESOZOIC ERA

Stage 1 Breakup of Pangaea - During the three Periods of the Mesozoic, we will see a four-stage breakup of the super-continent of Pangaea - The iceless super-continent will dominate most of the Triassic Period from 251 – 220 MY - Beginning at ~220 MY (Middle Triassic Period), Laurasia began splitting from Gondwana, which marked the opening of the North Atlantic Ocean. - The opening of the Atlantic began with a continental rift (divergent zone) in which the crust was arched upwards and pulled apart into fault blocks. - These fault blocks would be covered with sediments from the higher ground. - In the rifted fault blocks we find great thicknesses of sediments. - As the divergent zone continues to create the Atlantic, the “American” shoreline would remain and was now separated from the European shoreline - Within the “American” rifted fault blocks we will find associated great thicknesses of basalt flows and intrusions that occurred because of the rift. - These basalts are presently exposed along the Hudson River and are known as the “Palisades”. - These lava flows are thus a product of the Atlantic divergent zone. - Eventually, the rift widens enough to create the North American Ocean basin (Atlantic Ocean). - There will be living creatures here at the time of the rift. - For example, in the Connecticut River Valley, we find abundant reptile and dinosaur footprints.

Western Laurasia (North American) Triassic and the Sonoma Orogeny - At this same time, the west Laurasia coast (Western Pangaea) and Texas were located south of the equator. - There is a large desert found in the western portion of Laurasia - Off the western shore, another orogeny is in the making with a converging land mass - An island arc moved toward the earlier Antler sequence and this became known as the Sonoma Orogeny. - At this time, the mountains of the Paleozoic Antler Orogeny were deeply eroded and deeply faulted. - Orogeny: mountain building - This convergence will occur over what is presently part of Nevada and help create an ancestral Sierra Nevada Mountains

Triassic Red Beds - Erosional trends continue from the Permian, in which “red beds” of sandstones and shales were deposited on the western portion of the North American platform. - Red Beds: sediments with abundant iron oxides which imply desert-like conditions over a large area - An example of the Chinle Formation of Arizona was given - Spectacular displays of Triassic red beds can be found in the Palo Duro Canyon in the Texas panhandle near Amarillo. - Mentioned about the summer musical “Texas” that uses Palo Duro Canyon as a stage. - And dinosaurs would call this home

Triassic Life After the Permian - The Triassic Period marine fauna had a very low diversity from the Permian fauna but the surviving species tended to be abundant and widespread over the Earth’s oceans. - Life was beginning to rebound from the catastrophic extinction at the end of the Permian. 2

- Video of Beginning Triassic - A number of dinosaur species began to appear during the Triassic Period. - Dinosaurs would begin to rule the Earth, in one form or another for 186 MY, until they became extinct at the end of the Mesozoic Era.

Dinosaur Characteristics - Dinosaurs are egg-laying animals that can walk erect (not like today’s reptiles that have a sprawling walk). - Some dinosaurs and most reptiles had scaly skin - Some fossil evidence supports that all of the larger dinosaurs had scales. - There is also fossil evidence that some smaller dinosaurs had feathers and while others had some fur.

Dinosaur Name - The giant marine and flying animals of this time are referred to as flying reptiles and marine reptiles – NOT flying dinosaurs or marine dinosaurs (these creatures swam or walked with a sprawl). - Dinosaur: the name given to two related orders (Saurischia and Ornithischia) of extinct animals that appeared in the Triassic Period, especially beginning with the Late Triassic Period. Phylum: Chordata Class: Reptilia Subclass: Archosauria

Age of Dinosaurs - Many of the dinosaur species will arrive at the beginning of the Jurassic, with smaller numbers during the Triassic. - Let’s examine a list of known species of Triassic animals: Amphibians ------31 Mammal-like reptiles --- 35 Reptiles ------240 Dinosaurs ------54 Mammals ------7 Birds ------0

Some Mammal-like Triassic Animals - Cynognathus (sy-nog-NAY-thus): were to be found throughout all of Pangaea - They were mammal-like reptile carnivores, first found in the Permian Period. - They were reptiles and not dinosaurs and would become extinct at the Middle Triassic. - Lystrosaurs: Identical forms were found all over Pangaea. - They were very heavy and about 3 feet long. - They were a mammal-like herbivore that lived in vast herds in Pangaea. - This was the most abundant animal on the Triassic landscape. - These became extinct at the end of the Triassic. - Video of Lystrosaurs

Some Triassic Reptiles - Chasmatosaurus were Triassic crocodile-like reptiles resembling dinosaurs - There are noted by having a frontal curved snout full of exposed teeth - Video of Chasmatosaurus

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Some Triassic Dinosaurs - Coelophysis (see-lo-FISE-iss) was an eight (8) feet tall, 50 pound carnivore that probably hunted in packs and was one of the earliest dinosaurs - Video about Coelophysis - Plateosaurus was the largest herbivore at this time and was about 27 feet long - Video about Plateosaurus

Some Triassic Mammals - Morganucodon (MORE-gan-oo-CODE-on): oldest known (to date), tiny mammal dated at 225 MY or Middle Triassic - The smallest known Triassic mammal fossil ever found is Hadrocodium (the size of a paper-clip)

Some Triassic Marine Reptiles - The first reptile to return to the sea was the Northosaur. These reptiles were about 10 feet long that were probable ancestors to some Plesiosaurs - The Late Triassic saw the evolution of the first Plesiosaur - The early Ichthyosaur evolved during the Triassic; these fossils are found around the world and are less dolphin-like than late Ichthyosaurs - The Placodonts resembled turtles but lived only during the Triassic - Ticinosaurs were land-based reptiles but would become ancestors to the crocodiles

Triassic Animals Found in the Chinle Formation of Arizona - These would include: - Phytosaurs - Aetosaurs - Desmatosuchas - Placeras

Texas Triassic Reptile - Carnivore Postosuchus (also found in Texas) - Video of Postosuchus

Texas Triassic Bird? - Some think the Protoavis found in Post Texas is a type of bird

Reptiles in the Sky - Pterosaurs - Flying animal that had reptilian skulls, teeth and pelvises - A few are known from their fossils to have long dense fur. - It has been suggested that they were warm-blooded. - This includes the long-tailed Rhamphorhynchus - Other pterosaurs include the large Dimorphon - They are found from the Late Triassic to the Mesozoic extinction. - 2 Videos on Flying Reptiles

Triassic Extinction - The real age of the dinosaurs began at the end of the Triassic Period. - The end of the Triassic Period marked with another mass extinction. - 20% of all families would disappear 4

- 75% of all species disappeared, all in a relatively short period of time - Iridium found at the Triassic-Jurassic boundary strongly suggests a major asteroid impact. - The 210 MY, 62 mile-wide Manicouagan Crater, Quebec, Canada is a likely candidate-cause for this extinction.

THE JURASSIC PERIOD OF THE MESOZOIC ERA

Stage 2 Breakup of Pangaea - During the three Periods of the Mesozoic, we will see a four-stage breakup of the super-continent of Pangaea - During the Early to Middle Jurassic (200-160 MY), the creation (divergent zone) of the North Atlantic Ocean basin will separate Africa from North America - The GOM would have been opened at this time. - A land mass composed of Australia, India and Antarctica was breaking from Pangaea. - Existing paleographic maps are quite variable for this time period - Some of the existing maps imply that the Early Gulf of Mexico received its waters (which will evaporate to form thick salt deposits) from the North Atlantic and others imply a Pacific Ocean inlet. - The paleography of the opening of the Gulf of Mexico is not well understood. - One feature for sure, a lot of salt was evaporated from seawater in the Gulf of Mexico basin during the Jurassic

Early Jurassic Navajo Sandstone - Continuing from the Triassic, we initially see a western desert in North America - The North Atlantic will continue to widen - And there will be another land mass approaching (converging toward) North America from the west - About this same time, great quantities of sand will continue to erode from the eastern shore of western North America, forming great dunes of sand - This sand is the Navajo Sandstone Formation - The Navajo Formation reaches its maximum thickness of +2,000 towards its western edge - Today, the Navajo Sandstone forms spectacular landscapes in New Mexico, Colorado, Utah and Arizona. - Especially popular are the Vermillion Cliffs AZ but only 20 people a day are allowed to visit this site and only then by special permit, Also popular are the Antelope Slot Canyons near Page, AZ.

Nevada Orogeny and the Sundance Sea and Morrison Formation - We now see the beginning of the Nevada Orogeny during Middle Jurassic - Continuing to the Late Jurassic, two important features would greatly impact North America (a) Sundance Sea: an epicontinental sea that would cover portions of Western North America two – five (?) times; resulting in large deposits of shale and limestone (b) Second would be the Nevadan Orogeny that would create the Nevadan Mountains. This was done by a converging land mass and Island arc from the west - The erosion from these mountains would provide sediments eastward to fill up the sea basin there - As the Sundance Sea withdrew, there was the deposition of the Morrison Formation of shale, sandstones and fossils. - The Morrison Formation contains the world’s richest assemblage of fossil dinosaur bones.

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Stage 3 Breakup of Pangaea - This stage occurred in the Late Jurassic (~150 MY). - South America begins to split from Africa to create the South Atlantic Ocean, with the North Atlantic getting wider. - Australia, India and iceless Antarctica are still a single continent.

Life During the Jurassic - Let’s examine a list of known species of Jurassic animals: Amphibians ------11 (decreasing) Mammal-like reptiles ------0 (all gone) Reptiles ------163 (decreasing) Dinosaurs ------249 (increasing) Mammals ------39 (increasing) Birds ------2 (first appearance)

Dinosaurs - Many more of the dinosaurs will arrive during the Jurassic rather than during the Triassic - Video of Beginning of the Jurassic

- After the Triassic extinction, the number of dinosaurs greatly expanded - The dinosaur name is given to two related orders

Dinosaur Order Saurischia (saw-RIS-kee-ah) - Order Saurischia dinosaurs have hips pointing forward. - Includes carnivore suborder Theropods - And a herbivore suborder Sauropods - All dinosaur carnivores are theropods

Dinosaur Order Ornithischia (or-ni-THISS-kee-ah) - Order Ornithischia have hips pointing backwards. - Suborders include Ankylosaurs, Stegosaurs, Ceratopsians, and Ornithopods

Warm Blooded or Cold Blooded Dinosaurs - Endothermic: animals capable of regulating their internal body temperature, regardless of external temperatures - Some dinosaurs were probably Ectothermic like the fish and reptiles today - Ectothermic: relying on the environment and behavior to regulate body temperature

Evidence that Dinosaurs Were Warm Blooded - The following are arguments that dinosaurs were warm blooded, although each by themselves are not exclusive. - 1) Posture: limbs directly beneath their bodies - 2) Speed: dinosaur track ways indicate that many dinosaurs could move at rates comparable to mammals of similar size - 3) Predatory/Prey Ratios: cold-blooded ratio is 20%; warm-blooded ratio is 1% - 5%; dinosaur ratios have been calculated at 1% - 5%, similar to warm-blooded creatures - 4) Paleographic Distribution: Dinosaurs lived at the poles where daylight times and temperatures would be highly variable 6

- 5) Bone Histology: porous bones indicate numerous blood vessels and warm blood - 6) Colonial Nesting: a warm-blooded trait - 7) Evidence of Parental Care: this is not an exclusively a warm-blooded trait - 8) Possibility of Migration: as evidenced by track ways and body distribution - 9) Fossil Dinosaur Heart: cat-scan of fossil suggests a warm-blooded creature

- Feathered flying and non-flying reptiles suggest warm-blooded creatures

Birds - They made their first appearance in the Late Jurassic. - Characteristics include: feathers, warm-blooded, a keeled breastbone and a wishbone - Original ancestor was a probably small, bipedal theropod. - Many small theropod fossils show imprints of feathers.

Archaeopteryx - Oldest known bird fossils - Six Jurassic specimens have been found with Solnhofen limestone of Germany. - Characteristics include: claws on front and rear limbs; conical teeth in jaws; light-weight feathered body and a long boney tail.

Jurassic Sauropods - Includes Diplodocus, the largest Jurassic land animal at 90 feet long, and weighing 10-20 tons - Major museums of the world display mounted skeletons of these dinosaurs - Two videos of Diplodocus - Includes Apatosaurus (a-PAT o-Sawr-us) aka Brontosaur - Also Brachiosaurus (BRACK-ee-uh-SAWR-us) that was 82 feet long and 43 feet high and weighed 28-70 tons - Video of Brachiosaurus -Other Sauropods include Cetiosaurus, Massospondylus and Rhoetosaur

Jurassic Order Ornithischia - Includes the stegosaur at 30 feet long, 9 feet high and weighing 3 tons - Major museums of the world display mounted skeletons of these dinosaurs - Two videos of Stegosaurus

Jurassic Theropods - These are mostly carnivores - There will be at least 7 species of Allosaurus - Allosaurus are not related to T-Rex - Allosaurs are 40 feet long, 17 feet high and weigh 2-4 tons - Major museums of the world display mounted skeletons of these carnivores - Two videos of Allosaurus - Other Jurassic carnivores include Ceratosaurus - Eustreptospondylus (yoo-STREP-to-spon-di-lus) lived along shorelines and islands (these were a type of Megalosaurus) - Video of Megalosaurus

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Jurassic Marine Reptiles - The seas were dominated by giant swimming reptiles - Video of swimming reptiles - Large marine swimming reptiles (not dinosaurs) evolved to rule the marine realms of the Mesozoic Era - Beginning in the Jurassic, we saw the appearance of a famous marine reptile – the ichthyosaurus - There will be many different species of these animals - Video of Opthalmosaurus – an Ichthyosaurus - Their fossils are found around the world. These animals had the largest eyes of all known reptiles

- The Triassic Nothosaurs would evolve into Plesiosaurs - The Jurassic saw the appearance of two types of Plesiosaurs - For one, their necks would be 8 feet long during the Jurassic but much longer during the Cretaceous - One type would include the small 8 ton Cryptoclidus (crip-toe-CLIDE-us) - Video of Cryptoclidus - There was a short neck variety called Pliosaurids - These marine reptiles had large heads with strong jaws and short necks - Liopleurodon got up to 40 feet long and weighed 25 tons - Video of Liopleurodon

End of the Jurassic Period - There would be a minor mass extinction toward the end of the Jurassic Period - During this extinction, most of the Stegosaurids and many of the enormous Sauropods died out - Also becoming extinct were many genera of ammonoids, marine reptiles and bivalves - No one knows what caused this Jurassic extinction - Video of End of Jurassic

THE CRETACEOUS PERIOD OF THE MESOZOIC ERA

Stage 4 – Pangaea Breakup - This stage occurred during the Cretaceous Period (~144 MY). - Europe and Africa became widely separated from the Americas. - North America and Greenland begin to split apart. - Antarctica (with minor glaciers), India and Australia split apart. - Epicontinental seas were widespread in the Jurassic and Cretaceous which deposits thick sequences of limestone on the cratons. - Sea levels were very high, in fact, these were the highest sea levels seen during the Paleozoic Era. - The major epicontinental sea would flood the area between the eastern and western portions of the US and cover most of Texas. - This would represent the last major epicontinental sea over North America. - Video of Beginning Cretaceous

The Sevier Orogeny - This orogeny developed on the western US coast. - During this orogeny, large granite batholiths were emplaced because of a convergent zone. - We find these granite batholiths from Baja California to the California-Nevada border through the Canadian Pacific coast

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The Cordilleran Orogeny - The Early Jurassic Nevada Orogeny and the following Cretaceous Sevier Orogeny are part of a larger orogeny call the Cordilleran Orogeny. - Cordilleran: an extensive chain of mountains that form the principle mountain range of a continent. - The Laramide Orogeny overlapped the Sevier Orogeny and continued into the Cretaceous Period (all three orogenies create the Cordilleran Orogeny).

Cretaceous Limestone of Texas -In Texas, we find large deposits of limestone associated with the Cretaceous sea. - This is very evident as you drive west past road cuts from Austin or San Antonio or Dallas - The Cretaceous limestone formations are very fossiliferous because most of the Cretaceous seas in Texas were shallow. - It is even possible to see oil-bearing limestone in some road cuts.

The Glen Rose Formation - The Glen Rose Formation is important for the large number of dinosaur footprints that are found within these rocks. - Dinosaur Valley State Park, Glen Rose TX (near Fort Worth) has lots of footprints and bones and some giant models. - These footprints show that the Cretaceous sea was at times a tidal flat with nearby islands. - We see evidence of a carnivore dinosaur following a herbivore. - Most of the footprints are found in the shallow Paluxy River. - Adjacent to this state park is also a “Creationist Museum” - Giant herbivore footprints are found in the Blanco River by Blanco Texas. - Dino footprints can also be seen at a private park nearby Canyon Lake Texas - Lots of shallow water fossils can be found along most Glen Rose Formation along road cuts - This formation has produced hundreds of millions of barrels of oil. 9

Edwards Formation - Also deposited in the Cretaceous was the Edwards Formation, an area of both shallow seas and deep seas. - The shallow Edwards Formation forms the Edwards Aquifer for the San Antonio area. - Most of the Texas tourist caves formed in the Edwards Limestone - At depth, the Edwards Limestone has produced more than 450 million barrels of oil

The Eagle Ford Shale - Overlying the Edwards formation is the Eagle Ford Formation (mostly shale) - This represents a time of shallow seas and deeper seas with deposition of lots of mud - The Eagle Ford is the site of intensive oil and gas exploration - All of this is possible because of directional drilling and fracturing or fracing with sand and water and will likely produce several billion barrels of oil. - Fossil fish have been found in the Eagle Ford

The Austin Chalk Formation - Overlying the Eagle Ford Formation is the Austin Chalk - The Austin Chalk is a famous Texas oil and gas producer

Life During the Cretaceous - Let’s examine a list of known species of Cretaceous animals: Amphibians ------6 (decreasing) Mammal-like reptiles ------0 Reptiles ------343 (increasing) Dinosaurs ------629 (increasing) Mammals ------89 (increasing) Birds ------101 (increasing)

Cretaceous Amphibians - Apparently Cretaceous frogs were hopping around - There have been many recent discoveries of these fossil frogs in Liaoning China - But the largest frog was the giant Beelzebufo from Madagascar that ate baby dinosaurs

Cretaceous Mammals - Maybe a surprise, but many “small” Cretaceous mammals would appear - This includes the 70 MY old Volaticotherium, a probable flying squirrel - The largest mammal at this time was Repenomamas (China) that was about three feet long - Their fossils have shown that they ate baby dinosaurs because one such fossil shows this

Multituberculate Mammals - These type were the longest living mammal order for around 100 MY - This opossum-like animal order is the only branch of mammals to become extinct - Fossil teeth and jaws have been found in Dallas - They were probably marsupials and were the most common mammal in the Cretaceous - Videos of Cretaceous Mammals

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Flying Reptiles Pterosaurs - Quetzalcoatlus - Largest flying animal that ever lived - They had wing spans of 36 feet, a neck 10 feet long and legs over 7 feet long. - They probably weighed over 300 pounds. - Their fossil bones are found within the Big Bend National Park. - Video of Flying Reptiles

Marine Reptiles Plesiosaurs - Plesiosauroids: During the Cretaceous, species had necks that were 30 feet long and body lengths of more than 46 feet.

Marine Reptiles Mosasaurs - These giant marine mosasaur reptiles arose during the Late Cretaceous. - These are classified as being the closest relative to a snake - Within the stomach of one fossil was a plesiosaur - They were snake-like reptiles with body lengths of 60 feet in length. - Fossils of these have been found in the Dallas area and in the Big Bend National Park.

Cretaceous Fish - Giant ray-finned fish like the Teleost swam the seas

Marine Invertebrates - Bivalve mollusks species greatly increase - Mobile echinoderm (sea urchins) species increased. - Modern types of corals appeared (scleractinian). - Giant Texas oysters - Exogyra ponderosa – are called the devil’s toenails were common - Ammonite species greatly increased and are common in Texas.

Plants - Spore-bearing plants dominated the Paleozoic Era. - Seed-bearing, non-flowering plants (gymnosperms) dominated the Mesozoic Era - Seed-bearing, flowering plants (angiosperms) would emerge in the Late Cretaceous and became dominant during the next Cenozoic Era.

Dinosaurs in Texas :Texas State Dinosaur - The giant herbivore Paluxysaurua Jonesi is the Texas state dinosaur - It was 30-60 feet long, weighed 10-45 tons - It was a sauropod of a brachiosaurus lineage - Incomplete skeletons and footprints are found in the Glen Rose Formation

Dinosaurs Can Be Found in Texas - Torosaurus had a skull 8.5 feet long, with a body 25 feet long and weighed 4-6 tons. - Torosaurus and triceratops are related (the former may be a mature version of the latter) - Video of Torosaurus

- Ankylosaurus: was 35 feet long, 1-5 ton herbivore with extremely heavy armor - Video of ankylosaurus - Iguanodon herbivore that was up to 40 feet long, and weighed 3.5 tons 11

- Video of Iguanodon - Hadrosaurus (duck-bill dinosaur) was 23 feet long and weighed 2.5 tons - Video of Hadrosaurus - Alamosaurus (a huge Sauropod herbivore) has also been found in the Big Bend National Park; it was 50 feet long and more than 30 tons in weight. - Bones of the herbivore Tenontosaurus and carnivore Deinonychus have been found in the Dallas area. - The raptors were very efficient killers that hunted in packs - Utahraptor was 23 feet long, 15 feet tall and up to one ton with long sharp claws - Video of Utahraptor

T -Rex - The largest land carnivore ever evolved during the later Cretaceous - The smaller allosaurus carnivores had already became extinct - The famous Tyrannosaurus rex was about 20 feet tall, 40 feet long and weighed 5-7 tons -Video of T-rex

The End of the Dinosaurs: Chicxulub - About 65 MY ago, a six-mile wide asteroid named Chicxulub would be captured by Earth’s gravity. - The rock was traveling at +120 miles/second and would impact at a site located within the Yucatan Peninsula of Mexico, less than 600 miles from Texas. - When Chicxulub touched the Earth’s surface, the top part of the asteroid would be more than 32,000 feet in the air! Impact results of Chicxulub: -a) 600 miles away (Corpus Christi) in 5 seconds, most organic life was burned by the heat of the entry and impact; the blast front winds arrived 48 minutes later at 2,520 mph and a 100 foot tall tsunami arrived 5 hours later -b) at 1,000 miles away (Dallas area) all organic life was burned with a visible fireball 70 miles in diameter; blast winds arrived 1.36 hours later at 717 mph -c) at 1,500 miles away (Denver area) most organic life was burned by the heat of 4 inches of molten rock fragments 14 minutes later; blast front winds arrived 2.3 hours later at 393 mph -d) at 2,000 miles away (near Seattle) most organic life burned from 2 inches of molten rocks; blast front winds arrived 2.7 hours later at 213 mph

- Dust and soot would have clouded Earth’s atmosphere for months – if not for years. - No dinosaurs survived after the impact (except for birds). - The rare metal iridium found in world-wide 65 MY old ash layers confirm the meteorite impact. - The initial crater was about 108 miles in diameter (180 kilometers) and was discovered in 1991. - The crater would later be buried by more than 3,000 feet of limestone rock. - Later core drilling would find molten rock and soot from the time of the impact.

End of the Mesozoic - The arrival of the asteroid Chicxulub ended the age of the dinosaurs and the Mesozoic Era. - The dinosaur extinction allowed the rise of the mammals. - Video – End of the Mesozoic Era

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The Cenozoic Era (Chapter 23)

Cenozoic Era Components - In the US, the Cenozoic is divided into two periods: - Quaternary Period: 2.588 MY to Present - Tertiary Period: 65 MY – 2.588 MY -The Cenozoic is divided into seven epochs: - Oldest to youngest: Paleozoic (for 9.2 MY), Eocene (for 21.1 MY), Oligocene (for 10.9 MY), Miocene (for 17.7 MY), Pliocene (for 2.5 MY), Pleistocene (for 2.58 MY), and Holocene or Recent (for about 12,000 years) - Most of the Western US landforms that we see today were created during the Cenozoic Era.

Laramide Orogeny - Although this orogeny began during the late Cretaceous, most of its effects occurred during the Cenozoic. - This was the most severe of the three-part Cordilleran Orogeny. - This orogeny is responsible for the mountains that extend from Alaska to Mexico to Guatemala - The Laramide Orogeny ended with the Eocene Epoch (important to remember).

Subduction and the Laramide Orogeny - The effects of the Laramide were different from the other North American orogenies. - Normally, the oceanic crust would be subducted at an angle of about 500 beneath a continental crust with coastal metamorphism and igneous activity occurring only about 120 miles inland. - The Laramide Orogeny took place much further inland than is typical for an oceanic crust – continental crust convergence - The subducted oceanic plate did not dive deep but moved as a shallow, sub-horizontal plate under the continental crust. - This orogeny created mountains as far east as Colorado and West Texas - A new idea has been proposed about the Laramide Orogeny that makes use of a mantle plume. -As the orogeny began during the Cretaceous, there was a mantle plume or hot spot that developed offshore from North America near the subduction zone - During the Paleocene and the beginning of the Eocene, North American “overrode” this subhorizonal oceanic crust and mantle plume. - Laramide deformation was mostly in the forms of vertical uplifts and faulting. - There would be very few intrusions and volcanoes during Laramide time. - The “overriding” stopped at the Middle Eocene - This was the end of the Laramide Orogeny and the end of the western US mountain building

The Paleocene Epoch

Back to Tectonic events in the Paleocene - India continues its trek toward Asia - Later, the land masses of Greenland and North America would begin to separate from one another - Sub-tropical conditions will prevail in Greenland and North America continue with very warm climates

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Cretaceous – Paleocene Seas - At the end of the Cretaceous and into the Pliocene Epoch, the seas covered a much smaller portion of North America. - However, a greater portion of Texas and Florida were still submerged by the Gulf of Mexico - The epicontinental Cannonball Sea survived out west (Wyoming and surrounding states) during the Pliocene. This large sea was populated by large sharks.

Coal - As the epicontinental sea receded from the Wyoming area, huge, massive swamps would form and would continue to exist here for hundreds of thousands of years. The vegetation from these swamps would eventually form massive coal deposits. - These US coal deposits provide coal reserves that can be mined and used for hundreds of years. - These western coal deposits average up to 90 feet in thickness and have only a few feet of dirt covering them. Thus the coal can be mined creating minimum environmental damage. - Remember that the eastern US (Appalachian Mts.) coal requires removal of large hills and small mountains to obtain the coal. - This western coal burns much cleaner than the US Eastern coal from the Appalachians

Paleocene Life - Chicxulub basically destroyed most of the life on Earth. - It is with this backdrop that we begin to examine how life (that survived Chicxulub) would evolve in the Paleocene Epoch. - Paleocene means “ancient recent life” - At the very beginning of the Pliocene, the most common vegetation was not trees but ferns and this is known as the “fern spike” - But soon, deciduous trees (trees that shed leaves annually) would recover from the Chicxulub event and would cover much of the Earth’s land surface. - Animal survivors of Chicxulub would be small mammals (generally 20-30 pounds), birds, amphibians, small reptiles and insects.

Mammals - Mammal: a class of vertebrates characterized by being furry and warm blooded, with special glands to provide milk for their young. - 13 orders of mammals are now extinct from the Pliocene. - Today there are 39 orders of mammals, which include 30 orders of placental mammals.

Proteria (Monotreme Mammals) - These are primitive egg-laying mammals - There are fossil records of Proteria mammals that go back to the Cretaceous Period (100 MY) and are represented by a fossil jaw and a few teeth. - The modern Monotremes may not be directly related to the more primitive Proteria animals. - Today’s Monotremes are mammals that have fur, produce milk and lays eggs. - Modern Proteria mammals are represented by the platypus and echidna spiny anteater of Australia

Metatheria (Marsupial Mammals) - Marsupial mammals also first appeared in the Late Cretaceous and were the most abundant mammal during that time. - With marsupials, immature young must spend considerable time nursing in the mother’s pouch. - These include kangaroos, koala bears and opossums 14

- The vast majority of marsupials are found in Australia, because of its isolation.

Eutheria (Placental Mammals) - These also first appeared in the Cretaceous as insectivores. - Mammals which bear live young that have matured in the womb, nourished by the placenta. - This would include the armadillo. They are one of the few animals that can carry leprosy.

Animals of the Paleocene - Let’s examine a few mammals that began to evolve and diversify during the Paleocene. - Most animals would be smaller than an average size bear of today - Video of Cenozoic Life - The Multiberculates from the Cretaceous continued into the Paleocene. - Some may have been two feet long and weighed over two pounds - Pantolambra (a pantodont – extinct order) was a herbivore the size of a sheep - Creodonts were carnivores which became extinct at the end of the Early Cenozoic. - Birds, like Diatrymidae (Gastonis) became the number one predator being over six feet tall and weighing up to 500 pounds and more. - Some of their bones have been found in Florida and Texas. - Two videos of giant birds - Paleocene bats would evolve during this time - Today, bats make up 25% of today’s mammal species - The Primates (60 MY) would first appear in the Americas and Africa

The Paleocene Thermal Maximum - At the end of the Paleozoic, there was a sudden upset to Earth’s atmospheric and oceanic circulation pattern. - The oceans became warm down its deepest intervals. - At this time world temperatures rose by 11 degree (F) in less than 20,000 years. - There have been many suggestions but no definitive ones as to the cause of this event -End of Paleocene

The Eocene Epoch - Eocene means “dawn of recent life” - The Laramide Orogeny would come to an end during the Eocene - India would begin to converge upon Asia; the land mass of Australia and Antarctica would split apart - The Sahara Desert during the Eocene was covered by a shallow sea - Video Sahara Desert during Eocene - Thick deposits of sediments would “push” the Texas shoreline eastward - The Eocene Wilcox Formation is a major oil and gas producer - Eocene climate would be warm and free from frost almost world wide - However, the temperatures would begin to cool considerably as Antarctica reaches the South Pole.

Green River Formation - The temperature during the Paleocene and Eocene was almost tropical. -This allowed several huge lakes to form in the Utah-Wyoming-Colorado corner. - These ancient lakes would provide an idea environment for fish and their fossil remains - Within the Green River Formation have been found over a million fossil fish - You can pay and collect these fossils yourself on private lands. 15

- Massive quantities of oil shale are also found with the Green River Basin Formation and other nearby basins. - The shales of this formation have the capacity of producing more than two trillion barrels of oil. - But a large part of the shale is within very scenic areas (which causes a problem for mining).

Eocene Life - Whales would evolve from a land mammal to a giant sea mammal during the Eocene - Ambulocetus (waking whale) was 10 feet long and had no eternal ears - It spent a major part of its life in the water and swam with an up and down motion - Video of ambulocetus - In 10 MY, ambulocetus would evolve into the whale basilosaurus, a 60 feet carnivore. - Video of basilosaurus - Meanwhile on land, propaleotherium has often been portrayed as an ancestor to the horse - These mammals were about a foot high and weighed about 20 pounds -Video of propaleotherium - Video of birds eating horses - Eohippus was the true horse, having 3 hooves and standing about 14 inches tall - Primates continue to evolve with opposable thumbs - A remarkably complete primate fossil – Darwinius – has been found in Germany - Primate fragments have been found in Eocene sediments near Laredo - Andrewsarchus (of extinct order Mesonychid) was the largest land mammal carnivore of all times. - Its skull was 3 feet long and 2 feet wide and the animal weighed over a ton. - It had hooves that resembled sheep -Video of Andrewsarchus - Eocene titanoboa at 42 feet long and weighing 2,500 pounds was the largest snake ever

Climate Change - The climate would begin to change toward the end of the Eocene - Video of Eocene climate change - This would give rise to the Brontotherium, a rhino-like mammal that stood about 8.5 feet tall - Video of brontotherium - Near Florissant (central CO), a volcano spewed ash over a nearby lake - Tens of thousands of fossil insects can be found here

Eocene Extinctions - The Eocene would end with a major mammal extinction on the land and in the sea. - Antarctica’s move over the South Pole would upset oceanic currents as some ice started to form there - With this cooling, the climate becomes drier, forests would get replaced by shrub lands and many orders of mammal would disappear -Video of Eocene end and climate change

The Oligocene Epoch - Oligocene means “slightly recent” - Video about the beginning of the Oligocene - With the Oligocene, there was an increase in volcanic activity - There was igneous emplacement of major ore deposits of gold, silver, molybdenum, copper, lead and zinc in the Western US

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- Volcanoes in the Texas Big Bend country (Dagger Flat) will spew uranium-rich ash that will be blown to South Texas which will later form major uranium deposits here - India is converging with Asia - Australia and Antarctica are now totally separated - It becomes cooler as glacial ice covers a large part of Antarctica but there is no ice at the North Pole. - This will lead to a drop in sea level -Toward the end of the Oligocene, Antarctica would begin to warm and much of this ice will melt - Many previous tropics will diminish to woodlands and grasslands - For the first time grass becomes widespread

Oligocene Life - During this epoch, new mammal forms evolved and expanded in an evolutionary radiation of many types - New kinds of mammals appear including prehistoric ancestors of dogs, cats, rhinos and hippos. - Mesohippus, a 3-toed horse was about 21 inches tall and ate shrubs instead of grass - Arsioitheres, a giant rhino-like mammal left no modern ancestor - Then came the incredible fierce, pig-like entelodonts that were 7 feet tall and 800 pounds - Video of entelodonts - The largest land mammal that ever lived was indricotherium that was 18 feet tall and weighed over 20 tons - Video of indricothere - Herbivore chalicothere was 7 feet tall, weighed 800 pounds and walked on their knuckles - Video of chalicothere - Carnivorous hyaenodon was 10 feet long and weighed over 100 pounds - Video of hyaenodon - Ancestors to elephants, mammoths and mastodons make their appearance - The Oligocene will end as the Earth starts to warm up again for the Miocene

The Miocene Epoch - The Miocene will be the longest of the Cenozoic epochs (18 MY) - Miocene means “less recent” - The world gets warmer than the Oligocene but then starts to cool down again - In the later Miocene, more ice starts to form on Antarctica - Many changes will occur over the western US.

Basin and Range Province - Remember from the Laramide Orogeny and the Eocene about the sub-horizontal oceanic plate that slid under western North America - During the Miocene, the lower mantle plume would eventually uplift the continental crust there - This uplift and faulting stretched the landmass of Nevada by more than 180 miles. - This stretching produced a series of mountains and valleys called the Basin and Range Province. - The Basin and Range Province is very evident in Nevada. - This province is easy to recognize by finding relatively flat terrain surrounded by long mountain chains. Today these basins are being filled by erosion from the nearby mountains. - Faulting is still active today, though most of the faulting occurred during the Miocene. - The Basin and Range Province covers a large part of the American southwest, including El Paso and the Big Bend National Park. - The greater part of the US copper, gold, silver and barite comes from this province 17

Colorado Plateau (Four - Corners Area) - The central part of the western US rose as a single huge block because it was composed of a thick, hard Jurassic sandstone - This feature is centered over the four states of CO, UT, AZ and NM is called the Colorado Plateau - This block would form a series of flat-lying sandstone plateaus that rises 3,000 to 5,000 feet about the surrounding terrain. - This is an area of spectacular landscape scenery and “natural bridges”

Miocene Igneous Activity - Deep fissures formed under the Columbia River valley - About 20 MY ago, a mantle plume forms under this area in Washington state - From these fissures, great quantities of basalt would cover the entire area (flood basalts) - Enough basalt would erupt to cover the entire US with 36 feet of basalt lava. - A “hot spot” has also developed under the Yellowstone Park and Snake River area. The geysers and earthquakes here imply deep magma movements are still active. - In the Wyoming-Nevada area, we find a series of intrusives, covered with basalt that shows the movement of the North American Plate westward for the last 15 MY - Igneous activity reached West Texas, including the Davis Mountains and the Big Bend area.

Miocene Life - Mammal diversity reaches its peak during the Miocene - There will be present both many ancient mammals and many present day mammals over North America - The megalodons shark was the largest predaceous shark that ever lived. They reached sizes of 66 feet and weighed 52 tons

End of Miocene - The end of the Miocene is marked by the extinction of many grazing mammals - And the first primates began to walk upright on two legs

The Pliocene Epoch - In 2009, a new “end date” of 2.558 was assigned to the Pliocene - Pliocene means “more recent” - The Himalayas will rise high enough to create deserts in Africa and Asia - The Antarctica is not yet fully frozen - The Mediterranean Sea will be dry during most of his epoch - The world is continuing to cool down - The San Andreas Fault became active with the opening of the Gulf of California 5.3 MY ago. - The Gulf of Mexico began filling up with sediments to its present shorelines.

Pliocene Life and Land Bridges - There will be fewer numbers of ancient mammals over North America - Most of the ancestors to our modern mammals would appear before the end of the Oligocene - A major change in North American fauna is about to occur in the Pliocene - With the lowering sea level, there will be a land bridge between Asia and North America - About 3 MY ago, North America and South America became connected by a land bridge. - This lead to the migrations of mammals to and from all of these continents. - South America had been isolated from North America for most of the Cenozoic 18

- South American mammals were predominately marsupials that had a parallel evolution with the North American placental. - It also led to the extinction of most of the South American marsupials and many herbivores. - The placental armadillo is actually an immigrant from South America. - 10% of South American mammals went North but caused little change in genetic biodiversity there. - 50% of North American mammals went South and lead to increased genetic biodiversity there.

Some Pliocene Life - Phororhacos (a terror bird) grew to more than 10 feet tall in South America and North America and lived until 15,000 years ago - They may have also lived in Texas and Florida - Video of terror birds - Smilodon was the last of a long list of such animals and this was the largest of all saber-toothed cats. - They were 5 feet long, 4.5 feet tall and weighed up to 1,000 pounds - Although saber teeth cats evolved in the Miocene (26 Y), the largest Smilodon evolved +2.5 MY ago and lived in South Texas -Video of Smilodon - Glyptodonts represent a large variety of VW-sized armadillos - Fossils of different varieties of these can be found locally - We commonly find their “scutes” or part of their body armor - Two videos of the South American glyptodonts - Fossils of megatherium are one of many giant ground sloths that can be found locally - They grew to the size of elephants and weighed 5 tons and could stand to 18 feet tall - Video of ground sloth - Man would arrive before the end of the Pliocene

The Pleistocene Epoch - Earth entered into an ice age in the Quaternary Period. - Pleistocene means “most recent” - This epoch marks the beginning of the last ice age - But this actual ice age in North America did not begin until 600,000 years ago - We are now in our fifth ice age on Earth - Ice Age: intervals in Earth’s history lasting millions of years during which the global climate is cold with giant continental glaciers present - At its maximum, ice will cover a third of Earth’s surface - Actually we are in an interglacial period of retreating continental glaciers.

Pleistocene Life - The whale will evolve as the largest animal that ever lived on Earth - Blue whales reach 108 feet long and weigh up to 190 tons - This also marked the emergence of the ice age megafauna, much of which lived in the Corpus Christi area. - Includes the giant American lion (larger than African lions), giant cave bears, giant camels, herds of llamas, many sizes of horses, giant javelin, large crocodiles, giant Galapagos tortoises, tapirs, manatees, giant beavers (+250 lbs) and three types of elephants – mammoths, mastodons and gomphotheres –ALL EXTINCT - Two videos of wooly mammoths SEE LAST PAGE 19

The Holocene or Recent Epoch - The Holocene Epoch is marked by the partial melting of today’s ice caps - This interglacial period marks the Holocene Epoch that we live in today. - This is where we are today with modern man ruling the Earth

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