Compare the use of inferences about the ecology, behavior, and physiology of extinct animals based on extant phylogenetic brackets with those based on analogies with living forms—for example, the inferences in this chapter about the social
behaviors of ceratopsian dinosaurs that were based on analogies with modern herbivorous mammals with horns or antlers. How might you test your conclusions in each case?
Both methods rest on comparisons of extinct animals with extant forms. A phylogenetically based comparison has the advantage of comparing forms within the same evolutionary lineage, and the strongest inferences can be drawn when ancestral traits have been retained by the species on the derived side of the comparison; the evaluation of parental care by dinosaurs is an example.
Few lineages have phylogenetic brackets that are as well placed as crocodilians and birds, however, and many questions can be addressed only by drawing analogies with unrelated extant forms. In these situations we rely on general similarities among vertebrates—for example, all terrestrial vertebrates are subject to the same abiotic conditions (e.g., gravity and the thermal environment). A response that is effective for one lineage may be effective for another lineage in the same environment. That phenomenon is the basis for many examples of parallel and convergent evolution.
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Fibronectin is a protein that helps hold cells in position within tissues
Indicate whether the statement is true or false
____________________ gated channels respond to stretching or other mechanical deformation
Fill in the blank(s) with correct word
The three portions of the sternum, from superior to inferior, are:
A) manubrium, sternal angle, xiphoid process. B) manubrium, body, xiphoid process. C) manubrium, xiphoid process, body. D) clavicular notch, body, sternal angle.
Before the mRNA transcribed from a gene can be used to translate into a protein, it must be
A) edited to remove introns. B) edited to remove exons. C) transported into the cytoplasm. D) edited to remove introns and transported into the cytoplasm. E) edited to remove exons and transported into the cytoplasm.