Optional Activities
- The Great Crawl: Give your learner two flat pieces of cardstock or unopened envelopes to hold like fins and try to push their weight across the floor. Then swap them for two sturdy rulers or thick markers and try again. The difference between a flexible ray-fin and a weight-bearing lobe-fin becomes immediately physical. Connect it to Tiktaalik: look at your arm, humerus, radius, and ulna, then look at the bone structure of Tiktaalik's lobe-fin. The same three bones. This activity works especially well for kinesthetic learners who need to feel the concept before they can talk about it.
- Find Your Inner Fish: The bones in your arm (humerus, radius, ulna) are directly homologous to the fin bones of Tiktaalik. Trace your forearm and compare it to a labeled diagram of Tiktaalik’s fin. You and a 375-million-year-old fish share the same skeleton.
- Mudskipper Video Study: Search for videos of mudskippers, living fish that “walk” on their pectoral fins and can breathe air for short periods. They are the closest living analogy to early Devonian fish transitioning to land. Watch and write 3 observations.
Digging Deeper Activities
- Homologous Structures Chart: Draw the forelimb bones of a human, dog, whale, bird, and bat. Notice all five have the same basic bones (humerus, radius, ulna, carpals, digits) in different proportions. This shared skeleton is evidence of a common tetrapod ancestor descended from Tiktaalik’s lineage.
- The Tiktaalik Prediction: In 2004, Neil Shubin and colleagues predicted where they would find a fish-to-land transitional fossil based on rock age and found Tiktaalik in the Canadian Arctic exactly where they expected. Research this discovery. What does it say about the power of evolutionary theory to make testable predictions?