1 / 19

HISTORICAL GEOLOGY MESOZOIC LIFE.

HISTORICAL GEOLOGY MESOZOIC LIFE. .

kobe
Download Presentation

HISTORICAL GEOLOGY MESOZOIC LIFE.

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. HISTORICAL GEOLOGY MESOZOIC LIFE. We have covered mainly marine invertebrates in the labs on Paleozoic life - many of these continued into the Mesozoic e.g. Crinoids, corals, sponges, bryozoa, many types of mollusk. On the field trip we will see that Ammonites (a cephalopod mollusk) and Gryphaea (an oyster) are abundant in Cretaceous (late Mesozoic) rocks of this area, while Crinoids are common in Pennsylvanian rocks (late Paleozoic). Harry Williams, Historical Geology

  2. But, we will focus on terrestrial life today. We need to step back and trace the origins of life on land to understand the life of the Mesozoic. Paleozoic marine vertebrates - Primitive FISH were common by the Devonian. Harry Williams, Historical Geology

  3. Paleozoic land plants: First appeared in the Silurian, probably from marine algae which invaded land along wet lowlands near the coast. These Psilophytes were vascular (internal tubes for transporting water and nutrients) and were strong enough to support themselves out of water. Harry Williams, Historical Geology

  4. Paleozoic land invertebrates: The plants paved the way for animal invasion of the land (plants=habitat and food). The first animal invaders were invertebrates: insects and gastropods – these had external shells to prevent drying out (the biggest problem when changing from marine to terrestrial). Harry Williams, Historical Geology

  5. With tragic results…. Harry Williams, Historical Geology

  6. Paleozoic land vertebrates: One group of bony fishes (Sarcopterygii sar-coptery-ge) had nostrils and lungs that allowed them to rise to the surface and breath air (oxygen required for metabolism). From these evolved the Dipnoans (meaning double breathers) in Gondwanaland, which became the modern lung-fish found in Australia, S. Africa and S. America. Another group of Sarcopterygii (the lobe-fin fish) had bony fore fins that allowed them to move over the land, probably to move around in very shallow water or to reach the next pond during times of drought. An example is the Devonian Eusthenopferon (use-fen-nop-fron). This group of fishes evolved into the first tetrapods - AMPHIBIANS. Harry Williams, Historical Geology

  7. Changes from fish to amphibian were to facilitate life on land: - 3 chambered heart developed to pump blood to new limbs - more efficient lungs - stronger limbs, body held further off ground - sturdy, but flexible spinal column - inner ear parts developed to hear in air ICHTHYOSTEGID Harry Williams, Historical Geology

  8. Paleozoic reptiles: Appeared in the Pennsylvanian. Most important distinction from amphibians = do not need to return to water to breed (young amphibians use gills, therefore must be born in water). How was this achieved? = the AMNIOTIC EGG - young developed protected in water-tight egg, hatched virtually in adult form. Ophiocodon - a permian fish-eating reptile. Harry Williams, Historical Geology

  9. Mesozoic terrestrial plants: Lowland swamps were characterized by ferns, rushes and cycads (palm-like trees). Primitive CONIFERS were found in the cooler uplands and became more abundant as the climate cooled at the end of the Mesozoic. By the early Cretaceous the ANGIOSPERMS appeared (carried enclosed seeds, "flowering plants") e.g. birch, maple, walnut, beech, sassafras, poplar, willow. These became dominant by the end of the Cretaceous, reflecting the success of INSECT POLLINATION. Harry Williams, Historical Geology

  10. Mesozoic marine vertebrates: Some reptiles returned to the sea e.g. Ichthyosaurs ("fish-lizards"), Plesiosaurs Help!! Harry Williams, Historical Geology

  11. Mesozoic land vertebrates: REPTILES: The Triassic BASAL ARCHOSAURS (Diapsid reptiles) were small bipedal reptiles which were the forerunners of dinosaurs. Harry Williams, Historical Geology

  12. DINOSAURS: The 2 main groups are: 1.Saurischia – (lizard-hipped dinosaurs): this group included both carnivorous (theropods – for example: Allosaurus, Deinonychus, Tyrannosaurus) and herbivorous (sauropods – for example: Apatosaurus, Brachiosaurus) dinosaurs. Sauropod Theropods Harry Williams, Historical Geology

  13. FRONT LIZARD-HIPPED BIRD-HIPPED Harry Williams, Historical Geology

  14. 2.Ornithischia – (bird-hipped dinosaurs): this group included quadruped and biped plant-eaters. The jaws were beaked at the front and had grinding teeth at the back (for example: Hadrosaurs, Stegosaurs, Triceratops). Harry Williams, Historical Geology

  15. Pterosaurs – some reptiles developed the ability to fly (featherless). Archaeopteryx ("ancient wing") - The earliest known BIRD, appeared in the Jurassic Period. Had feathers, teeth, claws on the wing. A theropod descendant. Look out! Harry Williams, Historical Geology

  16. MAMMALS: Primitive shrew-like creatures appeared in the Triassic - probably insect-eaters. The big advantage they had over the reptiles is that they were ENDOTHERMIC (produced own heat internally from food). Reptiles are ECTHOTHERMIC (receive heat from sun - need warm climate). Our ancestor. Harry Williams, Historical Geology

  17. EXTINCTIONS The end of the Mesozoic is marked by mass extinctions: 1/4 of all known families were eliminated; marine plankton declined by 75%; Exinction of: Dinosaurs Ammonites Pterosaurs Ichthyosaurs Plesiosaurs Harry Williams, Historical Geology

  18. Causes? 1. Popular Theory = Asteroid Impact: Examination of the Cretaceous/Paleogene boundary has revealed a layer of red clay abnormally rich in IRRIDIUM - a metal that occurs rarely on the Earth's surface, but is frequently abundant in asteroids and meteorites -> theory that a large asteroid (10 km diameter) struck the Earth about 66 million years ago, near Chicxulub, Yacatan Peninsula, -> dust cloud (containing irridium) all over Earth -> abrupt climatic cooling -> death of many plants -> domino effect along food chains, killing off the most vulnerable species. Harry Williams, Historical Geology

  19. 2. Terrestrial Causes: slowing of mid-oceanic ridge growth -> eustatic sea-level fall -> loss of vast inland seas -> harsher, more extreme climates -> extinction of vulnerable species and those that depended on them (there is evidence of a colder climate at the end of the Mesozoic - conifers became more abundant/widespread; tropical plants declined). Dinosaurs could not live in cold climates. Evidence: extinctions possibly span up to 5 million years – argues against sudden Asteroid Impact. Also evidence of long (1,000’s of years) volcanic eruptions. Harry Williams, Historical Geology

More Related