How to Use This Simulation
Step 1: Choose an evolutionary transition (Fish to Tetrapod, Dinosaur to Bird, or Land Mammal to Whale).
Step 2: For each trait, select what you think the transitional form would have (between ancestor and descendant).
Step 3: Click "Check My Prediction" to see how your prediction compares to the real fossil!
Key concept: Transitional forms have INTERMEDIATE features - not fully ancestral, not fully descendant, but IN BETWEEN.
Choose an Evolutionary Transition
Design Your Transitional Form
What features would an organism "in between" have? Select one option for each trait:
Want to try a different evolutionary transition?
The Real Transitional Fossil
Why Transitional Forms Matter
Transitional fossils show us evolution "caught in the act." They have a MIX of features from both ancestral and descendant groups. Scientists predicted these forms would exist BEFORE finding them - proving that evolution makes testable predictions! When you design a transitional form, you're doing the same thing paleontologists do.