 Both groups of myriapods share similarities, such as long, multi-segmented bodies, many legs, a single pair of antennae, and the presence of postanntennal organs, but have many differences and distinct evolutionary histories, as the most recent common ancestor of centipedes and millipedes lived around 450 to 475 million years ago in the Silurian.The head alone exemplifies the differences; millipedes have short, elbowed antennae for probing the substrate, a pair of robust mandibles and a single pair of maxillae fused into a lip; centipedes have long, threadlike antennae, a pair of small mandibles, two pairs of maxillae and a pair of large poison claws.Millipedes come in a variety of body shapes and sizes, ranging from to around in length, and can have as few as eleven to over a hundred segments.