| Trait | How it helped adaptation to land |
|-----------------------|-----------------------------------------------------------------------------------------------------------------------------------------------|
| Lobe fins | Helped with support and propulsion on land, allowing for better movement |
| Single limb bone | Increased stability and flexibility in the limbs for weight-bearing and maneuvering on land |
| Nostril connected to mouth | Allowed for breathing air while still being able to keep the mouth closed underwater, adapting to changing environments |
| Weight-bearing elbows | Allowed for weight support and better leverage when moving on land |
| Bending wrist | Increased range of motion and ability to support weight when pushing off the ground |
| Neck | Allowed for better mobility of the head and increased ability to see and detect predators or prey |
| Digits | Provided better grip and support on land, allowing for grasping objects and navigating varied terrain |
| Pelvis attached to rest of skeleton | Provided stronger attachment for hindlimbs and better support for weight-bearing and movement on land |
| Loss of thick bony scales | Reduced weight and allowed for more flexibility in movement on land |
| Gills lost | Forced ancestors to rely on lungs for breathing air, enabling them to survive and adapt to terrestrial environments |
| Tail fin reduced | Increased maneuverability on land and decreased drag in terrestrial environments |
| Wrist and ankle structure | Provided stability and flexibility for weight-bearing and movement on land |
| Five digits | Allowed for better grip, balance, and finer manipulation of objects on land, aiding in hunting, gathering, and tool use |
| Loss of external fin rays | Helped improve flexibility and movement on land, as well as increased dexterity and versatility in adapting to diverse terrestrial habitats |
Ray-finned fish/Coelacanth- Bory skeleton, lungs (later lost in many living fish)
Lungfish - Lobe fins (single large bones in fins attached to shoulder and pelvic girdle)
Eusthenopteron - Panderichthys - Single large limb bone articulates to two smaller bones, nostril connected to mouth
Tiktaalik - Weight-bearing elbows, bending wrist, neck
Acanthostega- Forelimbs and hindlimbs with digits, pelvis attached to rest of skeleton, loss of thick bony scales covering the back and flanks
Ichthyostega- Gills lost, tail fin reduced
Tulerpeton- Wrists make contact along the entire span of hand ankle makes contact across the entire span of foot, each hind limb has two thin shin bones (tibia and fibula)
Living tetrapods - Five digits, wrist and ankles turned forward for walking on land, loss of external fin rays
Create a chart to explain how each trait described would have helped the ancestors of living tetrapods adapt to living on land.
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