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Can ancient DNA reveal the secrets of dinosaur evolutionary history? Sadly, no. DNA decays far too quickly to be present in fossils as old as dinosaur fossils are. But all is not lost; the paleontologist Mary Schweitzer and her colleagues have discovered, in some exceptionally well preserved dinosaur fossils, what appear to be preserved soft tissues, such as blood, bone marrow, and skin. These discoveries were initially met with great skepticism that soft tissues could be preserved for so long, but as additional evidence has accumulated, an increasing number of paleontologists have accepted the discoveries. Researchers have extracted proteins such as hemoglobin, keratin, and collagen from the fossil tissue, and the amino acid sequences of these proteins may reveal previously unknown information about the evolution of dinosaurs. Nonetheless, evolution’s historians must, for the most part, rely on more traditional methods. What have such methods revealed about the dinosaur’s successors as Earth’s dominant large animals, the mammals?
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Biology
- Genomics and Human Evolution The Denisovan genome contains sequences that originated from an unknown human species. Using Figure 19.11, speculate on which species this might be. Is it possible that there are other ancestral species that may remain to be discovered that would change the phylogeny presented in the figure? FIGURE 19.11 Estimates for the dates of origin and extinction for the three main groups of hominins (green, blue, and orange). The australopithecines split into two groups about 2.7 million years ago. One of those groups, the genus Homo, contains the ancestors to our species, H. sapiens.arrow_forwardBased on their anatomical and behavioral differences, biologists previously placed humans and chimpanzees in different families, but now DNA sequence data suggest that they are closely related and should be placed in the same family. What are some advantages of using DNA sequences to decide how to classify organisms? What might be some disadvantages?arrow_forwardChanges in the traits of the fossils studied are consistent with what is expected to be favored by natural selection, given environmental changes during that time. Thus, from the late Miocene, modern horses evolved to have the following traits, consistent with grassland ecosystems becoming more common, EXCEPT for -- A. Formation of hooves and fused forelimb bones. B. Teeth adapted for browsing rather than grazing.. C. A muscle and tendon system allowing for a springing motion in galloping. D. Larger animals better designed for grazing.arrow_forward
- Based upon the mutation that your dinosaurs have, are there any environmental changes in which the mutants would be better adapted than the non-mutants? If so, which? Dinosaur type: Maiasaura Mutation: Development of web-like tissue between digits (fingers).arrow_forwardClimate change is affecting the chemistry of the world's oceans. In particular, the ocean water is becoming more acidic. For purple sea urchins, this poses problems as their calcium-based exoskeletons may dissolve in acidic conditions. In a certain population of purple sea urchins, some individuals possess a trait that makes their exterior more resistant to acid. If global climate change continues (as predicted) to make ocean water more acidic, how might this population of purple sea urchins evolve in response to this increased acidification? A:Purple sea urchins with a trait of having shorter, more flexible spines would become more common. B:Purple sea urchins with a trait that make their exoskeletons less resistant to dissolving in acidic water would become more common. C:Purple sea urchins with a trait that make their exoskeletons resistant to dissolving in acidic water would become more common. D:Purple sea urchins with a trait of having longer, more rigid spines would become…arrow_forwardAlong with other geological evidence from rocks and structures, fossils give us clues about past climates, the motions of plates, and other major geological events. Which of the following statements does NOT support the evidence of evolution? * A. Fossils are records of structural changes that happen to organism B. Humans have stopped evolving. C. Fossils provide clear evidence of evolution. D. There may be similarities between different species due to a common ancestor. Davao is known for its wide variety of fruits and other plant species that makes it more attractive to tourists, which of the following classification of the value of biodiversity is described? * A. Direct economic value B. Indirect economic value C. Aesthetic value D. both A and Carrow_forward
- The name for the monophyletic group of animals that includes all reptiles, mammals, birds, and amphibians is the ----- . This group is characterised by the evolution and shared presence of ----- . However, some members of this group do not possess this feature because of a process called ----- loss. Snakes are famously legless reptiles, but other reptiles have also lost their limbs to varying degrees. Within the family ---- , we see species that have no limbs and some that have only hind limbs. In the genus ---- we can find species that have fully pentadactyl limbs, as well as those with only 3, 2, or 1 --- per foot.arrow_forwardAlong comes Dr Phil Bell and deep in the mines of Lightning Ridge, finds an amazingly preserved pterosaur that preserves feathers. He hypothesises that this means that feathers must have evolved before the origin of dinosaurs and therefore must have been primitive. How would you go about testing this hypothesis of feather origins?arrow_forwardA number of scientists believe that the Permian extinction was caused by huge volcanic lava flows (from the Siberian traps) that may have caused low oxygen concentrations compared to the high oxygen levels in the Permian. Does this low oxygen level after the Permian extinction make it likely that dinosaurs, especially large ones, did not evolve immediately after the Permian extinction (252 million years ago)? Why or why not?arrow_forward
- Carbon-14 dating works for fossils up to about 75,000 years old;fossils older than that contain too little 14C to be detected. Mostdinosaurs went extinct 65.5 million years ago. (a) Can 14C be usedto date dinosaur bones? Explain. (b) Radioactive uranium-235 hasa half-life of 704 million years. If it was incorporated into dinosaurbones, could it be used to date the dinosaur fossils? Explainarrow_forwardFossilized remains of prehistoric mastodons show anatomical similarities to modern-day elephants. These similarities provided the first evidence that mastodons were related to modern-day elephants. Which of the following is the BEST additional evidence that mastodons were related to elephants? A. Mastodons walked on four legs like modern-day elephants. B. Mastodon tissues contained proteins with similar amino acid sequences compared to modern-day elephants. C. Mastodon fossils were found in the same area where modern-day elephants live. D. Mastodons ate a diet similar to that of modern-day elephants.arrow_forwardWhat can skeletal anatomy and DNA sequences in existing primates tell us about the study of human evolution?arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage LearningHuman Biology (MindTap Course List)BiologyISBN:9781305112100Author:Cecie Starr, Beverly McMillanPublisher:Cengage Learning