- Humans: Have relatively longer and more robust upper arm bones (humerus) and forearm bones (radius and ulna).
- Bats: Possess shorter upper arm bones and elongated, slender forearm bones. This modification allows for greater maneuverability during flight.
2) Joints and Mobility:
- Humans: Have ball-and-socket joints at the shoulder, elbow, and wrist. This joint structure provides a wider range of motion, including rotation, flexion, and extension.
- Bats: Have modified shoulder and elbow joints that provide increased flexibility for flapping and folding of the wings during flight.
3) Finger and Claw Structure:
- Humans: Have five digits (fingers) on each forelimb, each with separate bones and joints.
- Bats: Have modified fingers with elongated bones, forming the framework of their wings. The fingers support a flexible membrane of skin, known as the patagium, that extends between them. Bats typically possess only a small claw on the thumb, while the other digits are elongated and lack claws.
4) Muscle Attachments and Wing Membranes:
- Humans: Have well-developed muscles in their forelimbs primarily for grasping and manipulating objects.
- Bats: Have specialized flight muscles attached to their forelimbs. Powerful flight muscles, known as pectoralis major and supraspinatus, are responsible for flapping the wings. Additionally, bats have elastic ligaments and connective tissues that form the wing membranes.
5) Function:
- Humans: Use their forelimbs for various activities such as reaching, grasping, climbing, and manipulating tools.
- Bats: Utilize their forelimbs primarily for flight and navigation. They are essential for aerial locomotion, including flapping, gliding, and maneuvering in the air.