The First Bird ■ 267(^12) Fill in the tree below to show the evolutionary relationships
among the domains and kingdoms of life.
Domains
Kingdoms
Common
ancestral cell
or universal
ancestor
Tr y Something New
(^13) In each of the following cases, which domain(s) or kingdom(s)
might contain organisms with the traits described?
(You may need to review Figure 14.9 to answer.)
a. motile, with flagella or cilia
b. All organisms within the domain or kingdom are single-celled.
c. found in extreme environments (for example, high temperature,
low oxygen, high salt)
d. multicellular with organ systems
e. photosynthetic
(^14) The traditional dinosaur-bird tree (Figure 14.6, top) can be
restated as a hypothesis: “We hypothesize that Archaeopteryx
is an early bird, and that birds split off from the closely related
dinosaur groups Troodontidae and Dromaeosauridae.” Restate Xu’s
tree (Figure 14.6, bottom) and Godefroit’s tree (Figure 14.14) as
hypotheses.
Leveling Up
(^15) Write Now biology: early life on Earth Read the New York Times
article “World’s Oldest Fossils Found in Greenland” (http://www
.nytimes.com/2016/09/01/science/oldest-fossils-on-earth.html).
Answer the following questions, writing one paragraph for each.
a. Summarize the findings of the study reported in the Times in
your own words.
b. If the scientific community reached a consensus that these are
not fossils, how would this conclusion affect our understanding
of early life on Earth? Explain why such a conclusion would not be
a failure of the scientific method, but rather a natural result of it.
c. Define the Late Heavy Bombardment (LHB). Describe how our
understanding of the LHB has changed, and how this change
has influenced our hypotheses about early life on Earth.
(^16) Is it science? Some people became quite upset when scientists
agreed that the dinosaur Brontosaurus was in fact Apatosaurus,
that Triceratops was only a juvenile Torosaurus, and that Pluto
was not a planet. They clung to their Brontosaurus, or Triceratops,
or planet Pluto, dismissing the scientists’ arguments by saying,
“Scientists are always changing their minds.” Explain how
scientists’ “changing their minds” is not a problem but instead
a necessary and useful feature of science, using the science
described in this chapter as an example.
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