Lecture Notes: Geologic Time Scale, Pt 3 - Dinosaurs PDF

Geologic Time Scale: Special Dinosaur Edition 1 DINOSAURS!!! If one examines GEOLOGIC TIME SCALE, they notice that dinosaurs appeared during the TRIASSIC PERIOD approximately 230 million years ago. Dinosaurs ultimately disappeared at the end of the CRETACEOUS period, approximatel...

Geologic Time Scale: Special Dinosaur Edition 1 DINOSAURS!!! If one examines GEOLOGIC TIME SCALE, they notice that dinosaurs appeared during the TRIASSIC PERIOD approximately 230 million years ago. Dinosaurs ultimately disappeared at the end of the CRETACEOUS period, approximately 65 million years ago. Thus, they roamed Earth for 165 million years! In fact, the MESOZOIC ERA (which includes the TRIASSIC, JURASSIC and CRETACEOUS PERIODS) is known as the AGE OF THE DINOSAURS! https://geologyscience.com/geology- branches/paleontology/geologic-time-scale/ 2 DINOSAURS!!! What’s wrong with the picture shown here? 1. Dinosaurs did not have rockets or backpacks. 2. Not all dinosaurs we have come to recognize lived (and died out) at the same time! Stegosaurus (which lived during the Jurassic) was extinct 80 million years before Tyrannosaurus (which lived during the Cretaceous). These three organisms never met!!! The two never met! Tyrannosaurus Rex died In fact, amount of time between out approximately 65 million Stegosaurus and Tyrannosaurus is greated years ago, during the K-T than the time between us and mass extinction. Tyrannosaurus! 3 DINOSAURS!!! When dinosaurs appeared approximately 230 million years ago (during the TRIASSIC PERIOD), the CONTINENTS were all stuck together, forming the supercontinent known as PANGEA. During the 165 million years of dinosaur existence, PANGEA gradually broke apart due to motion of Earth’s TECTONIC PLATES. By the time dinosaurs went extinct 65 million years ago, continents started resembling what we see today. TRIASSIC PERIOD: JURASSIC PERIOD: CRETACEOUS PERIOD: TODAY 225 million years ago 150 million years ago 150 million years ago 4 DINOSAURS!!! Tyrannosaurus Rex is one of the dinosaurs that went extinct 65 million years ago. The largest Tyrannosaurus Rex ever discovered comes from Saskatchewan (a Canadian Province). Discovered in 1991, the Tyrannosaurus Rex known as Scotty must have one time weighed approximately 9.8 tons. Scotty at the Royal Saskatchewan Museum. It took over 20 years to remove Scotty’s fossil from the rock, resulting in a skeleton that is about 65% complete! Scotty, can be seen at the Royal Saskatchewan Museum. Why did the dinosaurs die out 65 million years ago? Where did everyone go? 5 DINOSAURS!!! 65 million years ago, Earth experienced the K-T (MASS) EXTINCTION EVENT K = Kreide (German for chalk and refers to CRETACIOUS PERIOD) Word CRETACIOUS comes from CRETA, which is Latin for CHALK. K-T EXTINCTION EVENT that wiped out CRETACIOUS PERIOD is named after large quantities approximately 80% of animals thought to be caused of CHALK (a form of LIMESTONE, made up of calcite, by asteroid impact (or impacts). CaCO3) it left behind in Europe. Such impacts ejected debris into the atmosphere, T = TERTIARY (the period after CRETACIOUS) blocking sun and preventing photosynthesis. K-T EXTINCTION EVENT ushers in the end of This would be catastrophic to food chains. CRETACIOUS, beginning of TERTIARY PERIOD. May also have other factors such as changes in climate, volcanoes, sea levels, etc… 6 DINOSAURS!!! Firstly, let’s get it out there. NOT all dinosaurs died out as a result of the K-T EXTINCTION EVENT. Birds are dinosaurs and therefore theoretically reptiles. Some AVIAN DINOSAURS (the ancestors of today’s birds) survived the K-T EXTINCTION EVENT whereas all NON-AVIAN DINOSAURS died out. BAMBIRAPTOR (before and after fossilization) is a MANIRAPTORAN dinosaur Birds likely descended from MANIRAPTORAN that lived during the CRETACEOUS PERIOD. dinosaurs (from the MANIRAPTORA dinosaur group/clade). MANIRAPTORA is group/clade of THEROPOD dinosaurs that PALEONTOLOGISTS believe birds were derived from approximately 150 million years ago during the JURASSIC PERIOD. The royal albatross, today’s largest flying bird. 7 DINOSAURS!!! Thus, birds are dinosaurs (or at the very least, their descendants). THEROPOD DINOSAURS: dinosaurs with hollow bones and 3 toes/claws on each limb. Like birds, MANIRAPTORANS feature a PROPATAGIUM. PROPATAGIUM: a thin feathered fold of skin on wing that helps organism to obtain lift when flying or gliding. PROPATAGIUM location on a pigeon wing. Birds are dinosaurs (or at the very least, their descendants)!!! 8 DINOSAURS!!! As mentioned, some birds survived the K-T EXTINCTION EVENT. Other survivors include: alligators, crocodiles (reptiles) lizards, turtles (reptiles) frogs, salamanders (amphibians) Alligators and crocodiles survived the K-T EXTINCTION EVENT IMPORTANT for us: some mammals also survived the K-T EXTINCTION EVENT!!! Turtles survived the K-T EXTINCTION EVENT. 9 DINOSAURS!!! Some mammals also survived the K-T EXTINCTION EVENT!!! Mammals at that time were quite small. One survivor was PURGATORIUS, one of the earliest known primates and therefore one of our earliest human ancestors! I am PURGATORIUS, an early I am a tarsier, a PRIMATE!!! PRIMATE!!! He looked a bit like a squirrel ☺. PRIMATES are mammals that: have hands and feet that grasp have relatively large and complex brain have vision that sees objects in 3 dimensions Examples of PRIMATES include: humans, I am an orangutan, a PRIMATE!!! apes, monkeys, lemurs, tarsiers. 10 DINOSAURS!!! A fun video presenting dinosaurs and their evolution up until K-T EXTINCTION EVENT. Evolution of Dinosaurs in 10 Minutes. https://www.youtube.com/watch?v=qWvzBCfF Nug At 243 million years old, Nyasasarus Parringtoni is believed to be oldest known dinosaur! It lived in southern region of PANGEA during TRIASSIC PERIOD. It was size of a larger dog (e.g., Labrador) 11 My 6 dinosaurs!!! Thank you for an awesome semester!!! 12