Caminalcule Phylogenetic Exercise

William I. Ausich
Ohio State University
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Imaginary creatures (caminalcues) are used as an introduction to the methods, assumptions, and conclusions of phylogenetic analysis.

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I have used this exercise at several levels, from an undergraduate paleontology course for majors to graduate courses in paleontology

Skills and concepts that students must have mastered


How the activity is situated in the course

This exercise is completed prior to any detailed discussion of phylogenetic methods and interpretations.


Content/concepts goals for this activity

The goal is to have students think about the practical questions, decisions, and limitations of interpretations that are part of a phylogenetic analysis

Higher order thinking skills goals for this activity

analysis of data, formulation of phylogenetic hypotheses and evaluation of alternative phylogenies, etc.

Other skills goals for this activity

Description of the activity/assignment

To prepare students to think about the data, assumptions, and interpretations that are part of a phylogenetic analysis. This exercise comes in five parts. The first part is all of the data -- all specimens and age dates for all specimens. This simulates the impossible -- a complete fossil record. The second part has 10% of the specimens randomly removed (an imperfect fossil record), but all age information is provided for the 90% given. Similarly, the third and fourth parts have 20% (different 20%s) of the data randomly removed, and all information is provided for the 80% of remaining specimens (a more imperfect fossil record). The fifth part has dates only for the modern forms -- all other dates are removed. This simulates the situation for a group lacking a fossil record or a situation where the fossil record is ignored.

Depending on the class size, students either individually or in groups develop a phylogeny from their data prior to class time. In class we lay everything out on tables and compare and contrast the various phylogenies and in the process discuss many of the basic assumptions, practices, biases, etc. of phylogenetic reconstruction.

You could make this more complex and have students code things into MacClade, Paup, etc.; however, I use this for the concepts of phylogenetic reconstruction only.

Determining whether students have met the goals

Evaluation is based on a lively discussion by all students

More information about assessment tools and techniques.

Teaching materials and tips

Other Materials

Supporting references/URLs

Sokal, R.R. 1983a. A phylogenetic analysis of the caminalcules. I. The data base. Systematic Zoology, 32:159-184.
Sokal, R.R. 1983b. A phylogenetic analysis of the caminalcules. II. Estimating the true cladogram. Systematic Zoology, 32:185-201.
Sokal, R.R. 1983c. A phylogenetic analysis of the caminalcules. III. Fossils and classification. Systematic Zoology, 32:248-258.