CLADISTICS 20-QUESTIONS: A PALEONTOLOGY GAME FOR FIELD TRIPS

During a long van ride from the field, paleontology students were overheard playing a version of the old game “20 Questions.” I suggested that one could identify any real organism, living or fossil, given only 10 questions, if they could supply the correct answers based on material we had covered in class: in practice, it usually required only 7 or 8 such answers to identify their chosen organisms. The “questions” were based on the basal monophyletic lineages we had studied, plus the dichotomous (or in some cases polytomous) evolutionary pathways based on shared derived characters (synapomorphies). We all realized that besides being a good way to pass long rides, the game reinforced both the logic of cladistic taxonomy and basic paleontological data. It also challenged me to create questions that followed crucial evolutionary pathways to minimize their number: essentially I was forced to apply the principle of parsimony, which is fundamental to cladistic analysis.

Students perceived the power of cladistics in classifying organisms from knowledge of ancestral characters (plesiomorphies) and evolutionary novelties (apomorphies). I learned that cladistics is a powerful classification tool down approximately to the Order level, but that it requires many additional steps to key out lower taxa. This suggests that a mixed cladistic and Linnean taxonomic model may prove the best practice in both teaching and application of evolutionary paleontology.