Verhoeff was one of the most prolific authors of myriapod taxa in history. It is widely agreed that the insect, myriapod and crustacean heads are very similar. The largest-known myriapod by far was the giant "Arthropleura". Although a prolific describer of species, his legacy to myriapod taxonomy has been mixed. The myriapod fauna contains 500 Chilopoda and 1500 Diplopoda. Myriapod legs show a variety of modifications in different groups. A millipede is a myriapod with two pairs of legs on most segments. It is the first myriapod, and the oldest known creature to have lived on land. The myriapod head is very similar to that of the insects. The oldest known fossil land animal, "Pneumodesmus newmani", is a myriapod.