Centipedes and millipedes are some of the oldest land animals known from the fossil record. The oldest fossil land animal is a millipede about 428 million years ago. This fossil millipede has spiracles, evidence that millipedes at this early date breathed air and were fully terrrestrial. Centipede fossils date to the same time period, about 418 million years ago.
Data from DNA indicate that Centipedes and Millipedes formed separate groups prior to 430 million years ago. One open question about millipedes and centipedes is which came first: The movement onto land? or The split into millipede and centipede? A split after their common ancestor had moved onto land would mean respiratory systems for breathing air and likely to be very similar. A split from a common ancestor that was still aquatic would mean that millipedes and centipedes colonized the land in separate events and less similar adaptations. The fossil evidence of millipedes and centipedes during this period is scant. In the future, more molecular analysis may resolve this and other questions.