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Download Fossils Show changes in species over time
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Evolution Evolution means change. Biological Evolution: The process by which modern organisms have descended from ancient organisms. Evidence for Evolution Fossils – evidence of life in the prehistoric past Trilobite molds and casts http://www.discoveringfossils.co.uk/W hatisafossil.htm Fossil Evidence Ammonite Cast Serpent Starfish cast Fossil Evidence Fish Imprint Fossil Evidence Hard Parts Shark Teeth Dinosaur Teeth Fossil Evidence Hard Parts Mammoth Molar Mammoth Tusk Fossil Evidence Footprints From Dinosaurs Fossil Evidence Microscopic Fossils Bacteria – 3.5 Billion Years Old Algae – 1.2 Billion Years Old Fossil Evidence Coprolites – Fossilized “Poop” Dinosaur coprolites Amber-fossilized tree sap Fossil Evidence Whole Organisms Insects in Amber Frozen Mammoths Stefan Lovgren for National Geographic News April 8, 2005 Woolly Mammoth Resurrection, "Jurassic Park" Planned A team of Japanese genetic scientists aims to bring woolly mammoths back to life and create a Jurassic Park-style refuge for resurrected species. The effort has garnered new attention as a frozen mammoth is drawing crowds at the 2005 World Exposition in Aichi, Japan Fossils Show changes in species over time Evolution of the horse Fossils Show changes in species over time Evolution of the horse Two major trends – larger size, fewer toes Transitional Fossils Tiktaalik – The fish that found its feet How Old are the Fossils? Fossils are usually found in sedimentary rock. Relative Dating – Older fossils are on the bottom. (Law of Superposition) Type fossils – If you find the same “type fossils” in two different rock layers, they are of the same age. How Old are the Fossils? Absolute dating: Measure the amount of radioactivity left in rocks. What does the Fossil Evidence Show? 1. Life has changed throughout Earth’s history. 2. Organisms that are here today are different than life forms of the past. 3. Different species did not all appear at the same time. 4, Extinction has been a common occurrence throughout Earth’s history. 5. Transitional fossils show links between organisms. Archaeopteryx Homologous Structures Homologous structures – parts shared by different organisms that have been inherited from a common ancestor. These parts may have been modified for different uses. (Descent with modification) humerus radius ulna carpals metacarpals phalanges Tinkering – The Panda’s Thumb The panda has descended from carnivorous ancestors. It eats mainly bamboo and has a “thumb” that helps to hold the bamboo. The thumb is a modification of one of the wrist bones Analogous Structures The wing of the butterfly, and the wing of a bird are analogous structures. Analogous structures have the same function but do not have the same structure. The butterfly wings do not have bones, but the bird wing does. The wings have a different evolutionary past. Homologous Structures Analogous Structures Dog leg Bat Wing Dog leg Human eye Lizard eye Whale eye Insect leg Octopus eye Vestigial Structures Structures found in living organisms which no longer serve a useful function. They were inherited from an ancestor who did use them. Tail bone of humans Rear leg bones and claw on snake Rear leg bones of whales Vestigial eyes on blind cave fish Figure 2.2.2. X-ray image of an atavistic tail found in a six-year old girl. A radiogram of the sacral region of a six-year old girl with an atavistic tail. The tail was perfectly midline and protruded form the lower back as a soft appendage. The five normal sacral vertebrae are indicated in light blue and numbered; the three coccygeal tail vertebrae are indicated in light yellow. The entire coccyx (usually three or four tiny fused vertebrae) is normally the same size as the fifth sacral vertebrae. In this same study, the surgeons reported two other cases of an atavistic human tail, one with three tail vertebrae, one with five. All were benign, and only one was surgically "corrected" for cosmetic reasons (image reproduced from Bar-Maor et al. 1980, Figure 3.) http://www.youtube.com/watch?v=I2C-3PjNGok Vestigial Structures Bones from the atavistic hind-limbs of a humpback whale. A. From top to bottom, the cartiliginous femur, tibia, tarsus, and metatarsal, arranged as found in situ in the whale. B. Enlarged detail of the femur and tibia shown in A. (scale is not the same as A). C. Detail of the tarsus and metatarsal shown in A. Embryological Similarities Embryos of vertebrates show a similar development which indicates common ancestry. Biochemical Similarities All living things use DNA and RNA as the genetic material. All proteins in living things are built on the same 20 amino acids All living things use the same 3 base code for each amino acid. All living things use ATP as the direct energy source. Biochemical Similarities Hemoglobin is found in all these vertebrates. They have some different amino acids that make up the protein. The number of amino acid differences in the hemoglobin protein of two species is proportional to the length of time that has passed since they shared a common ancestor. The more similar the proteins are, the more closely related two species would be. Humans have a closer evolutionary relationship to a monkey than they do to a mouse. Geographical Distribution Darwin found 13 different species of finches in the Galapagos Islands. They were very similar but each species had slight differences in their size, beak and feet. They were also different from the finches found on the mainland of South America. The inference is that the ancestors of these birds made it to the newly formed islands. Here they evolved into all the species present on the islands today. Geographical Distribution Galapagos Tortoises Geographical Distribution Animals that are not closely related sometimes look similar because of similar environmental conditions which select for similar beneficial traits. Divergent Evolution An ancestral species evolves into many different species. Moose Elk White-Tail deer Mule Deer Black-Tail deer Ancestral Deer-like Species Key deer Convergent Evolution Two species that are not closely related appear to be very similar because they share similar environments. HUMAN EVOLUTION MYTHS • MYTH-Humans came from apes. • MYTH-Human evolution is a ladder with a series of steps directly leading from an ancestor to modern humans. • MYTH-Human characteristics evolved at the same time. HUMAN EVOLUTION MYTHS REVEALED • Humans and chimps represent 2 divergent branches of the anthropoid tree that evolved from a common ancestor • Not all fossils have been found, some fossils lead to a dead end. Not a ladder but more like a bush • Mosaic evolution- different features evolved at different times
