1. Appendix 2 The images on this CD have been lifted directly, without change or modification, from textbooks and image libraries owned by the publisher, especially from publications intended for college majors in the discipline. Consequently, they are often more richly labeled than required for our purposes. Further, dates for geological intervals may vary between images, and between images and the textbook. Such dates are regularly revised as better corroborated times are established. Your best source for current geological times is a current edition of the textbook, whose dates should be used when differences arise.

2. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Traditional system of hierarchical classification  In this ranking, the organism, an Eastern gray squirrel, belongs to the domain (Eukarya), kingdom (Animalia), phylum (Chordata), subphylum (Vertebrata), class (Mammalia), order (Rodentia), family (Sciuridae), genus (Sciurus), and species (Sciurus carolinensis).

3. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Cladogram used in classification  The tabulated morphological data are used to successively diagram the derived characters of the organisms thereby producing a phylogenetic tree that is a descriptive hypothesis of relationships. All organisms above the branch points share the character states noted along the way. To give direction to these changes, the outgroup, such as the lamprey, is used as a point of reference. It has none of the characters.

4. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display FIGURE A2.1 Evolution and Phylogenetic Trees  The actual course of evolutionary events is depicted on the left; the representation of these changes is summarized in a phylogenetic tree on the right.

5. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display FIGURE A2.2 Expressing Evolution  The same five species are presented in both of these phylogenetic trees, but there is a trade-off between simplicity and complexity of their relationships. (a) All are living species, so they are not likely the immediate ancestors of each succeeding group, as this simple scheme implies. (b) Actual ancestors (from A to D, respectively) lived millions of years ago and are now extinct. The five species living today are representative of the lineage, but likely are specialized in their own ways.

6. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display FIGURE A2.3 Classification  (a) Venn diagrams sort individuals into successive boxes of relatedness. Individuals of the same species are most closely related and put together in the smallest group—A, B, C, D, and O. If species A and B share more unique, derived features in common with each other than with any other species, then they are placed in a common group, and so on, expanding the diagram to include those more distantly related. (b) The genealogy of these species can be represented in the branching diagram, with the brackets representing Species A and B, together with their common ancestor, 1, at the branch, or divergence point. To make this dendrogram more useful, we could identify some of the many characters that change. For example, a horn first arises between divergence points 4 and 3; a second horn between 3 and 2; thick skin shields between 2 and 1.

7. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display FIGURE A2.4 Taxonomic Concepts  Taxon 1 is a monophyletic group because it includes all natural members of the lineage— the ancestor (solid circle) and all of the descendant groups (A, B, C, plus Aves). Taxon 2 is also a monophyletic group, including the common ancestor (open circle) and all descendants. However, the “reptilia” taxon is formally a paraphyletic group because it is somewhat artificial by not including Aves, one of the natural members of that lineage. Taxon 3 is a polyphyletic group, also artificial, because placing Aves and Mammalia together fails to include all other natural members between.

8. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display FIGURE A2.5 Extant and Extinct Groups  The richness of a dendrogram depends upon the number of species included. (a) Living (extant) groups are indicated. There is a close relationship between birds (Aves) and crocodiles (Crocodylia), which together are closely related next to lizards and snakes (Lepidosauria), and all these to turtles (Testudines). Mammalia is the outgroup. (b) Adding extinct groups illustrates the actual richness of the historical associations to the living groups (boxed).