Chicken Wing Dissection - Free Printable

This image shows a comparison of the forelimb bones in three different animals: a human, a bird, and a bat. Even though these limbs look very different on the outside (an arm, a wing, and a flying membrane), they share the same basic bone structure inside. This is called homology.

Here is how the bones match up across all three animals, based on the color key provided:

1. Humerus (Purple): This is the upper arm bone. It is the single large bone connecting the shoulder to the elbow area in all three animals.
2. Radius (Green) & Ulna (Red): These are the two forearm bones. They run from the elbow to the wrist. In the human, they are side-by-side. In the bird and bat, they are also present but may look slightly different in shape or length to support flight.
3. Carpals (Blue): These are the wrist bones. They are the small cluster of bones between the forearm and the hand/wing digits.
4. Metacarpals (Yellow): These are the palm bones. In humans, they form the palm of the hand. In birds, they fuse together to form part of the wing frame. In bats, they are extremely long to support the wide skin of the wing.
5. Phalanges (Orange/Brown): These are the finger bones. Humans have five fingers with multiple joints. Birds have reduced numbers of phalanges at the tip of the wing. Bats have very long, stretched-out phalanges that act like umbrella ribs to hold up their wing skin.

Key Takeaway:
Even though humans use arms for grasping, birds use wings for flying, and bats use wings for flying, they all evolved from a common ancestor that had this same five-part limb structure. Nature modified the size and shape of each bone for different jobs, but kept the same basic plan.

Final Answer:
The diagram illustrates homologous structures — specifically, the similar bone arrangement in the forelimbs of a human, a bird, and a bat. Each animal has one humerus (purple), two forearm bones (radius in green, ulna in red), wrist bones (carpals in blue), palm bones (metacarpals in yellow), and finger bones (phalanges in orange/brown). Despite differences in function (grasping vs. flying), the underlying skeletal blueprint is shared due to common ancestry.