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 3 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.