Cat and dog skeletons are designed for agility and speed, featuring a digitigrade stance (walking on toes), an axial skeleton (skull, spine, ribs) for protection, and an appendicular skeleton (limbs) for movement. Cats (approx. 230-250 bones) have more flexible,, lightweight spines with 30 vertebrae, and free-floating collarbones for extreme agility, while dogs (approx. 319-321 bones) have a sturdier, less flexible, and more rigid skeletal structure suited for endurance. 

Cat Skeleton (Feline Anatomy)

• Skull & Teeth: Lightweight with large eye sockets and a strong jaw, specialized for hunting.
• Spine: Highly flexible, with 7 cervical, 13 thoracic, 7 lumbar, 3 sacral, and 19-23 caudal (tail) vertebrae.
• Limbs & Claws: The clavicle (collarbone) is vestigial, allowing, allowing for increased flexibility. They have 5 digits on front paws, 4 on back.
• Adaptations: They possess a "floating" collarbone that allows them to squeeze through tight spaces and a supracondylar foramen on the humerus. 

Dog Skeleton (Canine Anatomy)

• Skull: Varies significantly by breed, with a sturdy structure and generally smaller orbit relative to the skull size compared to cats.
• Spine: Less flexible, designed for running and endurance.
• Limbs & Claws: Non-retractable claws used for traction. The shoulder blade (scapula) is not attached to the collarbone in a way that allows the same range of motion as a cat.
• Structure: They have more bones (approx. 319-321) than cats, reflecting a generally more complex muscular attachment. 

Key Differences

• Flexibility: Cats are significantly more flexible due to a more fluid spine.
• Collarbone: Cat collarbones are floating/vestigial, while dog collarbones are fixed.
• Claws: Cats have retractable claws, whereas dogs have non-retractable claws.
• Tail: Cats generally have longer, more flexible tails compared to many dog breeds.