HISTORY OF EARTH Geologic Time Mesozoic Era

1. HISTORY OF EARTHGeologic Time MesozoicEra

2. Mesozoic Era 251 mya to 65 mya Triassic Jurassic Cretaceous

3. THE HISTORY OF EARTHGeologic Time – Cretaceous The Long Age of “Dinosaurs” 145 myato 65 mya • Laurasia splits into North America and Eurasia asGondwanafractures into Africa, South America, Antarctica/Australia, and India (an island continent) • Shrinking Panthalassa becomes Pacific Ocean • Atlantic Ocean forms as Tethys continues to shrink • Climate warm and humid world-wide with vast forests • Broad shallow continental seas stabilize temperatures • Era ends when asteroid impact brings mass extinction

4. THE HISTORY OF EARTHGeologic Time – Cretaceous The Atmosphere Oxygen levels increased from their Jurassic levels. Oxygen samples collected from over 300 amber specimans around the world suggest that oxygen levels rose 50% above todays levels or from 25% to 35% concentration levels in the atmosphere. Carbon Dioxide also increased and reached levels two to four times what they are today. An 84-million-year-old air bubble trapped in amber. Using a quadrupole mass spectrometer (QMS), scientists can learn what the atmosphere was like in the past. Amber – from the fossilized resin of conifer trees - provides a unique means of protecting intricate samples of the past. This mosquito, lying trapped for many million years in a piece of amber, is almost perfectly preserved.

5. THE HISTORY OF EARTHGeologic Time – Cretaceous Plant Life Change in the composition of fossil leaf floras through the Cretaceous showing the impact of angiosperm diversification. Angiosperms (flowering plants) become dominant plant of the Cretaceous, first appearing in the Lower Cretaceous around 125 million years ago and radiating during the middle Cretaceous. As angiosperms were expanding, many modern groups of insects were beginning to diversify, and we find the oldest known ants and butterflies. Additionally, insects like aphids, grasshoppers, termites and ants appear. The eusocialbee appears during this period which was integral to the ecology and evolution of flowering plants. Eusocialityis an extreme form of social organization in which organisms care for young communally and give up reproductive rights to a queen. Diatoms are microscopic, unicellular algae that produce intricate silica cell walls. When diatoms die, their soft, internal parts deteriorate, leaving their hard, porous, glass skeletons behind. The Cretaceous also saw the first radiation of the diatoms in the oceans. There is debate among the scientists as to what made the angiosperms so successful.

6. THE HISTORY OF EARTHGeologic Time – Cretaceous Marine Life Some of the largest turtles ever to have lived on Earth appeared in the Cretaceous. Monstrous Mosasaurs inhabited the Cretaceous seas, reaching lengths of 50 feet. Clams developed into large forms four feet across. In the Middle Cretaceous there is a notable increase in the number of small marine life with mineralized skeletons and shells. Archelonischyros- swam the shallow seas of the late Cretaceous. Large front flippers and strong vertical strokes were used to propel itself through the water. This turtle reached 4 meters in length. Mosasaurs were very successful during the late Cretaceous period in which the largest mosasaour is Hainosaurusand could reach 17 meters in length. These were the top predator in the sea. Giant clams of today off the Great Barrier Reef today.

7. THE HISTORY OF EARTHGeologic Time – Cretaceous Mammals Mammals remain small and unobtrusive during this period. • Three types of mammals advance during this period: Steropodongalmani • 1. Monotremes • 2. Marsupials • 3. Placental mammals Kangaroo –with young, called a Joey, in pouch Marsupial are mammals without a fully developed placenta. As a result the young spend a comparatively short amount of time in the womb, usually two to five weeks, and are not fully developed at birth. They are born blind, hairless, and very tiny. They crawl up the mother's abdomen to the abdominal pouch, and immediately attach to a nipple. They spend months here until ready to go out on their own. A baby platypus Monotremes were mammals that laid eggs, like the modern platypus.Steropodon was a monotreme from the Early Cretaceous. A platypus is descended from this mammal. Koalas

8. THE HISTORY OF EARTHGeologic Time – Cretaceous We are #1 Placental Mammals Placental mammals give live birth to their young. The eomaiascansoria, a hairy 125-million-year-old shrewlikespecies, is the earliest known ancestor to most mammals alive today. Eomaiascansoria Mother of all placental mammals There are 18 orders of placential mammals today. Primates Gorilla Sirenia Pholidota Dermoptera Macroscelidae Xenarthra Colugo Anteater Manatee Pangolin Elephant Shrews Lagomorpha Chiroptera Proboscidea Tubulidentata Hyracoidea Pinnipedia Elephant Aadvark Vampire Bat Rabbit Hyrax Seal Carnivora Cetacea Rodentia Insectivora Perissodactyla Artiodactyla Zebra Mouse Mole Dolphins PolarBear Deer

9. THE HISTORY OF EARTHGeologic Time – Cretaceous Dinosaurs • Dinosaurs of every shape and size are in abundance by the Cretaceous. • Tyrannosaurs were a major predator in the Cretaceous. The most well-known member of this group being the Tyrannosaurus Rex. Joining Tyrannosaurus in the super predator category were the Spinosaurs and Carcharodontosaurs. • Some of the familiar dinosaurs that emerge in the Cretaceous are Iguanodons, the duck-billed Hadrosaurs and Triceratops. • All known fossilized eggs come from the Cretaceous. Does this mean that the egg shells themselves changed from a leathery reptile substance to a calcium carbonate such as modern eggs? If this change did occur, why and what were the advantages? The Cretaceous exhibited a diverse range of dinosaurs including maiasaurs (front left); tarbosaurs (top right), and pterosaurs (top center). In the foreground are depicted the first flowering plants and one of the earliest mammal relatives, both of which developed during this period and went on to survive the dinosaur extinction at the end of the Cretaceous.

10. THE HISTORY OF EARTHGeologic Time – Cretaceous tyrannosuarusrex T. rex's serrated, 30-cm long conical teeth were most likely used to pierce and grip flesh which it then ripped away from its prey. The edges of the teeth were sharp as knives and serrated. A large ferocious meat-eating dinosaur which had a thick heavy skull with a jaw 1.2-meter-long designed for maximum bone-crushing action. T.-rex was about 12 meters long and 6 meters tall. Its strong thighs and long, powerful tail helped it move quickly, and its massive 1.5-meter-longskull could bore into prey. Scientists believe this powerful predator could eat up to 230 kilograms of meat in one bite. Fossils of Triceratops in T.rex dung suggest T. rex crushed and broke bones as it ate.

11. THE HISTORY OF EARTHGeologic Time – Cretaceous spinosaurus giganotosaurus Giganotosaurusmeasured about 13 meters from head to tail and 7 m tall with about 3.6 mat its hip. Weight estimates put the dinosaur at between 6.5 tons and 13.3 tons. Itwalked upright on two large and powerful back legs. It is believed to have been fairly agile, thanks to its thin, pointed tail that may have provided balance and the ability to make quick turns even when running at top speed. It is estimated that Giganotosaurus could travel at speeds of up to 31 mph making it relatively fast for an animal its size. The largest of all known carnivorous dinosaurs, even larger than Tyrannosaurus and Giganotosaurus. It’s estimated that it was up to 18 meters in length and weighed 21 tonnes. The distinctive spines grew to at least 1.65 meters long. Recent evidence suggests Spinosaurs fed on fish and possibly sharks. The long narrow snout of Spinosaurus contained jaws full of sharply pointed teeth. Spinosaur teeth were smooth, round, and resembled the bite of crocodiles, where the upper teeth of the Spinosaurus interlock with the lower teeth. In addition, Spinosaurus had nostrils that faced upwards. A very useful adaptation for swimming and hunting fish.

12. THE HISTORY OF EARTHGeologic Time – Cretaceous iguanodons This was one of the first dinosaurs ever discovered. These plant-eating large dinosaurs were capable of walking on two legs or on all four. Their outstanding feature was a highly specialised, five-fingered hand made up of an erect and spiked thumb used for defense. Iguanodons reached about 9 meters in length and were believed to have traveled in herds.

13. THE HISTORY OF EARTHGeologic Time – Cretaceous hadrosaurs Among the last most numerousdinosaurs to roam the earth, the hadrosaurs(commonly known as duck-billed dinosaurs) were large, oddly shaped, low-slung plant eaters with tough beaks on their snouts for shredding vegetation. Most hadrosaurs are believed to have lived in herds and it is believed that some species paid close attention to their young.

14. THE HISTORY OF EARTHGeologic Time – Cretaceous tricertops Was approximately 9 meters long and 3 meters tall weighing between 4 to 6 tons. Stout limbs supported Triceratops's girth, but it was unlikely the dinosaur could move very quickly. Triceratopsprobably spent much of its time grazing on plant matter. It used its beaklike mouth and powerful jaws lined with rows of sharp cheek teeth to shred and grind cycads, ferns, and other low-lying vegetation. • Triceratops's head was its most imposing feature. It measured 1.2 to 1.5 meters across and was ornamented with impressive horns and a head plate. It used its horns—a short one above its mouth and two long ones above its eyes—to charge predators, such as T. rex. They likely were also used in mating rituals.

15. THE HISTORY OF EARTHGeologic Time – Cretaceous pterosaurs For the Pterosaurs it was their high point, their giant size dwarfing the smaller proto-birds who were developing rapidly and would dominate the skies of the post-Cretaceous world. Cearadactylus Was a large, mid-Cretaceous pterosaur with a wingspan estimated to be around 4 to 5.5 meters with a weight of around 15 kilograms. Its kinked upper jaw and its interlocking teeth suggest a piscivourous diet, allowing the animal to keep hold of slippery fish. Hatzegopteryx Pterosaurs didn’t get much bigger than this guy, standing over 5 meters tall and a wingspan of at least 10 meters. The skull was 3 meters long with a massive lower jaw. Ornithocheirus One of the largest flying creatures ever with a wingspan estimated up to 11 meters and had an enormous head relative to its body length. Its jaws supported numerous long, slender, pointed teeth, useful for catching fish and squid. The crest may have offered some aerodynamic advantage in flight or it may have been an indicator of gender or for species recognition.

16. THE HISTORY OF EARTHGeologic Time – Cretaceous pterosaurs Pteranodon Was a flying reptile about 2 meters long (or high) with an 8 to 10 meter wing span weighing up to 35 pounds. Like all Pterosaurs, the pteranodon had hollow bones, almost no tail and small bodies that may have had fur. Many pteranodons had light-weight bony crests on their heads and had no teeth. Pteranodonwings were covered by a leathery membrane. This thin but tough membrane stretched between its body, the top of its legs and its elongated fourth fingers, forming the structure of the wing. Claws protruded from the other fingers. Quetzalcoatlus Was a flying reptile whose wing-span was around 11 meters making it one of the largest flying animals ever found. Like the pteranodon, it had hollow bones, was lightly built, and had a small body with a toothless jaw and a long, thin beak. The neck was 3 meters long and the legs were over 2 m in length. It is currently believed that Quetzalcoatlusprobably relied on updrafts and breezes to help it fly.

17. THE HISTORY OF EARTHGeologic Time – Cretaceous Birds It’s believed that birds became increasingly common and diverse, replacing the pterosaurs which retreated to increasingly specialised ecological niches. Rahonavis Was it a raptor-like bird, or a bird-like raptor? Patagopteryx The South American Patagopteryxis believed to have been a land-bound bird, similar to modern chickens--and, like chickens, it seems to have pursued an omnivorous diet. Shenshiornisprimita This bird, dates back to 120 million years and was found in China and dates back to the early stage of birds' evolution. Crocaduck The dreaded crocaduck– half duck and half crock. Quacks like a duck but bites like a croc. x

18. THE HISTORY OF EARTHGeologic Time – Cretaceous CRETACEOUS MASS EXTINCTION • Approximately 60% of all species went extinct • Affected many land animals and plants • Affected fewer marine animals

19. THE HISTORY OF EARTHGeologic Time – Cretaceous What organisms became extinct? Dinosaurs Pterosaurs Ichthyosaurs Marine Animals Many Terrestrial Plants What organisms survived? Birds Mammals Trees with Flowers Fish, Squids, Sharks Lizards, Crocodiles, Turtle

20. THE HISTORY OF EARTHGeologic Time – Cretaceous What caused the extinction? Meteorite Impact Theory • 65 million years ago a 10 km wide meteorite struck the Earth near what is now the Yucatan Peninsula off Mexico

21. THE HISTORY OF EARTHGeologic Time – Cretaceous How could a meteorite impact cause a mass extinction event? The impact caused shock waves, tidal waves, and sent a tremendous amount of dust into the atmosphere, As the dust re-entered the Earth’s atmosphere, it would have instantly heated the atmosphere causing tremendous forest fires, Additionally, the dust could have caused the Earth’s climate to cool in the long-run by blocking sunlight. Plants, animals, etc went extinct due to the climate changes and competition between organisms

22. THE HISTORY OF EARTHGeologic Time – Cretaceous Evidence for the meteorite impact theory • Unique Quartz Crystals • Very commonly formed under high pressure/temperature. • This quarts has only been found in meteorite craters and nuclear testing sites. • Iridium • An element that is very rare in Earth rocks and very common in meteorites. • The layer of rocks above the last dinosaur bones contains ~160 times ‘normal’ levels of iridium.

23. THE HISTORY OF EARTHGeologic Time – Cretaceous Out-dated Extinction Hypotheses • Hay Fever - caused by flowering plants • Dinosaurs were so big, that they crushed themselves • Mammals out-competed the dinosaurs • Mammals ate all the dinosaur eggs • Cosmic rays killed the dinosaurs