Which animal is known to have the fewest coccygeal bones?

Humans are known to have the fewest coccygeal bones among the options listed. The human coccyx, commonly referred to as the tailbone, typically consists of four fused vertebrae, which is a remnant of what was once a tail in our evolutionary ancestors. This structure supports pelvic organs and provides attachment for ligaments and muscles.

In contrast, other animals have a greater number of coccygeal bones. For example, cats and dogs have a variable number of coccygeal vertebrae, ranging from about five to twenty, depending on the breed and individual variations. Horses also possess more coccygeal vertebrae, often numbering around 15 to 21, which contribute to their mobility and balance.

Thus, when comparing the number of coccygeal bones across these species, humans indeed have the fewest, due to the evolutionary adaptation and functional changes in the tail structure.