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Figure 24-9-Table 24-1. Figure 24-4a. Living species “succeed” fossil species. Present-day sloth from South America. Fossil sloth from South America. Transitional forms during the evolution of whales. Figure 24-4b. Pakicetus , about 50 myo. Ambulocetus , about 49 myo.
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Figure 24-4a Living species “succeed” fossil species Present-day sloth from South America Fossil sloth from South America
Transitional forms during the evolution of whales Figure 24-4b Pakicetus, about 50 myo Ambulocetus, about 49 myo Rhodocetus, about 47 myo Basilosaurus, about 38 myo
The human tailbone is a vestigial trait. Figure 24-5a Capuchin monkey tail Human coccyx (used for balance, locomotion)
Darwin reasoned that they share a common ancestor. Four mockingbird species on the Galápagos islands Figure 24-6 Galápagos islands Central islands Western islands Eastern islands Southern islands Nesomimus parvulus Nesomimus melanotis Mockingbirds from…. Eastern islands Southern islands Central islands Western islands Over time, the population diversified into several distinct species on different island groups An ancestral population colonized the islands Nesomimus macdonaldi Nesomimus trifasciatus
Homoplasy: Traits are similar but were not inherited from a common ancestor. Figure 27-2 Common dolphin Ichthyosaur Monotremes Ichthyosaurs Whales and dolphins Marsupials Synapsids Pterosaurs Elephants Dinosaurs Primates Rodents Lizards Birds The members of lineages between the dolphins and ichthyosaurs do not have adaptations such as: –streamlined bodies – long jaws filled with teeth –fins and flippers The dolphin and ichthyosaur lineages are far apart on the evolutionary tree, suggesting that they are not closely related Homology: Similarities are inherited from a common ancestor. Fruit-fly Hox complex Human Hox complex (insects, spiders, (snails, clams, crustaceans) (earthworms, sand dollars) Echinoderms (vertebrates) Arthropods Flatworms Chordates (sea stars, Mollusks The genes in the Hox complexes of fruit flies and humans have similar sequences and are in the same order on their chromosomes leeches) Annelids squid) Annelids, mollusks, and echinoderms also have Hox genes Infer that common ancestor had 8 Hox genes
Figure 24-7 Gene: Amino acid sequence (single-letter abbreviations): Aniridia (Human) eyeless (Fruit fly) Only six of the 60 amino acids in these sequences are different. The two sequences are 90% identical.
Figure 24-8 Gill pouch Gill pouch Gill pouch Tail Tail Tail Chick House cat Human
Figure 24-9 Humerus Radius and ulna Carpals Metacarpals Phalanges Seal Horse Bird Bat Human Turtle
Overall body size has decreased Figure 24-14 No net change in beak size over this interval Beaks have become more pointed
Figure 27-8a The Precambrian (Hadean, Archaean, and Proterozoic Eons) included the origin of life, photosynthesis, and the oxygen atmosphere. First oceans; heavy bombardment from space ends First evidence of oxygenic photosynthesis First rocks containing oxygen (in atmosphere and ocean) First evidence of photosynthetic cells First sponges; first bilaterally symmetric animals; ocean completely oxygenated First photosynthetic eukaryotes First red algae; first evidence of sexual structures Formation of solar system Earth formation complete Liquid water on Earth First lichen-like organism First eukaryotic fossils Moon forms Origin of life Hadean Eon Archaean Eon Proterozoic Eon All life is unicellular Multicellular organisms begin to diversify slowly Millions of years ago (mya) Position of the continents unknown Most of Earth is covered in ocean and ice.
Figure 27-8b Phanerozoic Eon: The Paleozoic Era included the origin early diversification of animals, land plants, and fungi. First ferns, vascular plants, ascomycete fungi, lichens on land First mycorrhizal fungi (Glomales) First comb jellies, arthropods, vertebrates, other phyla First tetrapods (amphibians) First mammal-like reptiles First basidiomycete fungi First bryozoans (newest animal phylum) First plants with leaves Arthropods diversify; first echinoderm First cartilaginous fish First winged insects First tree-sized plants First fish with jaws First seed plants First land plants First bony fish First insects First vessels in plants First reptiles Carboniferous Mass extinction Mass extinction Mass extinction Permian Cambrian Ordovician Silurian Devonian Mississippian Pennsylvanian Coal-forming swamps diminish; parts of Antarctica forested First upland plant communities (evergreen forests), diversification of fish, emergence of amphibians Insects diversify, coal-forming swamps abundant, sharks abundant, radiation of amphibians Echinoderms (sea stars, sea urchins) diversify Coral reefs expand Algae abundant, marine invertebrates diversify Laurentia Pangea Gondwana Gondwana Gondwana Supercontinent of Gondwana forms. Oceans cover much of North America. Climate not well known. Climate cold; extensive ice in Gondwana. Supercontinent of Laurentia to the north and Gondwana to the south. Climate mild. Supercontinent Pangea assembles. Building of Appalachian Mountains ends. Climate warm; little variation.
Figure 27-8c Phanerozoic Eon: The Mesozoic Era is sometimes called the Age of Reptiles. First angiosperm (flowering plant) First nectar-drinking insects First tyrannosaurid dinosaur First magnolia-family plants First bird (Archaeopteryx) First placental mammals First centric diatoms First water lilies First bee; first ant First dinosaurs First mammals Mass extinction Mass extinction Mass extinction Triasssic Jurassic Cretaceous Flowering plants diversify Gymnosperms become dominant land plants; extensive deserts Gymnosperms continue to dominate land Dinosaurs diversify Pangea Pangea Gondwana India separated from Madagascar, moves north; Rocky Mountains form. Climate mild, temperate. Pangea begins to break apart; interior of continent still arid. Gondwana begins to break apart; interior less arid. Pangea intact. Interior of Pangea arid. Climate very warm.
Figure 27-8d Phanerozoic Eon: The Cenozoic Era is nicknamed the Age of Mammals. First fully aquatic whales Oldest pollen from daisy-family plants Earliest hominins First primates First horses First apes Homo sapiens Paleogene Neogene Pleistocene Pliocene Paleocene Eocene Oligocene Miocene Diversification of mammalian orders Diversification of angiosperms and pollinating insects Diversification of grazing mammals Continents continue to drift apart. Collision of India with Eurasia begins. Australia moves north from Antarctica. Palms in Greenland and Patagonia. Strong drying trend in Africa and other continents; grasslands form. Alps and Himalayas begin to rise. Continents close to present position. Beginning of Antarctic ice cap. Opening of Red Sea. North and South America joined by land bridge. Uplift of the Sierra Nevada. Worldwide glaciation.
These two figures show former temperatures with major periods of glaciation labeled. The dashed lines are the present global average temperature of about 15° C (59° F). Thus the solid curves show small changes from this average; note that the temperature drops only about 5° C during a glaciation. This has occurred about every 100,000 years, with smaller wiggles in between. That is, there has been a 100,000 year glaciation cycle for the past million years or so, and there may be shorter cycles as well. http://vathena.arc.nasa.gov/curric/land/global/climchng.html
