A current view of how the human and chimpanzee can share most of their nucleotide sequences yet exhibit significant phenotypic differences is that many of the most important sequence differences alter ________.

#Question id: 4972

#Unit 11. Evolution and Behavior

Fossils of Lystrosaurus, a dicynodont therapsid, are most common in parts of modern-day South America, South Africa, Madagascar, India, South Australia, and Antarctica. It apparently lived in arid regions, and was mostly herbivorous. It originated during the mid-Permian period, survived the Permian extinction, and dwindled by the late Triassic, though there is evidence of a relict population in Australia during the Cretaceous. The dicynodonts had two large tusks, extending down from their upper jaws; the tusks were not used for food gathering, and in some species were limited to males. Food was gathered using an otherwise toothless beak. Judging from the fossil record, these pig-sized organisms were the most common mammal-like reptiles of the Permian. Anatomically, what was true of Lystrosaurus?

#Question id: 4969

#Unit 11. Evolution and Behavior

The snowball Earth hypothesis provides a possible explanation for the

#Question id: 4966

#Unit 11. Evolution and Behavior

If it were possible to conduct sophisticated microscopic and chemical analyses of microfossils found in 3.2-billion-year-old stromatolites, then within such microfossils, one should be surprised to observe evidence of:

I. double-stranded DNA

II. a nuclear envelope

III. a nucleoid

IV. a nucleolus

V. nucleic acids

#Question id: 4960

#Unit 11. Evolution and Behavior

Letʹs say that a hypothetical submersible robot was used to collect samples of sedimentary rock from the sea floor along the section illustrated. The robot moved back and forth along the transect, collecting first from site A, then site III, then site B, then site II, and lastly site D. Assuming that sedimentation has occurred at a constant rate along the transect over the past million years, rearrange the sites mentioned above on the basis of the thickness of the sediments overlying the igneous rock, from thickest to thinnest.

#Question id: 4959

#Unit 11. Evolution and Behavior

If a fossil is encased in a stratum of sedimentary rock without any strata of igneous rock (e.g., lava, volcanic ash) nearby, then it should be

#Question id: 4564

#Unit 11. Evolution and Behavior

Who would have proposed that the boundaries between each stratum mark the occurrence of different localized floods?