trends in marine Metazoa” by A. M. Bush and
R. K. Bambach (Annu. Rev. Earth Planet. Sci. 39:
241–269, 2011). Paleontologist and develop-
mental biologist Neil Shubin traces the history
of evolution of the human body in Your Inner
Fish: A Journey into the 3.5-Billion-Year History
of the Human Body (Allen Lane/Pantheon,
New york, 2008).
Terrestrial Ecosystems through Time: Evolution-
ary Paleoecology of Terrestrial Plants and
Animals (edited by A. K. Behrensmeyer et al.,
University of Chicago Press, 1992) presents
detailed summaries of changes in terrestrial
environments and communities in the past. E.
C. Pielou’s After the Ice Age: The Return of Life
to North America (University of Chicago Press,
1991) describes the effects of Pleistocene cli-
mate change on today’s ecology and distribu-
tion of species.Useful books on the evolution of major taxo-
nomic groups include J. W. Valentine, On the
Origin of Phyla (University of Chicago Press,
2004); P. Kenrick and P. R. Crane, The Ori-
gin and Early Diversification of Land Plants
(Smithsonian institution Press, Washington,
D.C., 1997); R. L. Carroll, Vertebrate Paleontol-
ogy and Evolution (W. H. Freeman, New york,
1988); M. J. Benton, Vertebrate Palaeontology
(Blackwell, Malden, MA, 2008); M. J. Benton
(ed.), The Phylogeny and Classification of the
Tetrapods (Clarendon, oxford, 1988); D. B.
Weishampel, P. Dodson, and H. osmolska,
The Dinosauria (University of California Press,
Berkeley, 1990); and D. R. Prothero, After the
Dinosaurs: The Age of Mammals (indiana Uni-
versity Press, Bloomington, 2006).PRoBLEMS AND DiSCUSSioN ToPiCS
- Why, in the evolution of eukaryotes, might it
have been advantageous for separate organisms
to become united into a single organism? Can
you describe analogous, more recently evolved,
examples of intimate symbioses that function as
a single integrated organism? - Early in the origin of life, as it is presently con-
ceived, there was no distinction between geno-
type and phenotype. What characterizes this
distinction, and at what stage of organization
may it be said to have come into being? - if we employ the biological species concept (see
Chapter 9), when did species first exist? What
were organisms before then, if not species?
What might the consequences of the emer-
gence of species have been for processes of
adaptation and diversification? - How would you determine whether the mor-
phological diversity of animals has increased,
decreased, or remained the same since the
Cambrian? What might bias your analysis? - Compare terrestrial communities in the
Devonian and the Cretaceous periods. Discuss
the differences between them in the diversity of
plants and animals, and develop some hypoth-
eses as to why those differences existed. - Read some papers (find them using any of sev-
eral literature-search engines that your instructor
can suggest) that make different estimates of the
timing of either the origin of bilaterian animal
phyla or the orders of mammals. How different
are the estimates based on molecular clock evi-
dence versus paleontological evidence? What
might account for these differences, and how
might they be resolved?- Animals that are readily classified into extant
phyla, such as Mollusca and Arthropoda,
appeared in the Cambrian without transitional
forms that show how their distinctive body plans
evolved. This “explosion” in fossil diversity had
to come from somewhere. What are some of
the best hypotheses explaining why animal fos-
sils are not found before the Cambrian, despite
molecular evidence suggesting divergence in
the much more distant past than that? - What is the evidence that the megafaunal
extinction in the Pleistocene was partly caused
by humans? - Many species expanded or changed their geo-
graphic range after the last (Wisconsin) glacier
retreated, about 12,000 years ago. What would
the consequences have been for the evolu-
tion of those species? What were the effects of
range changes on the species composition of
ecological communities? (See also Chapters 9,
18, and 19.) - What are some ways in which the evolution of
new life forms changed environments, from a
very local scale to a planetary scale?
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