It is now extinct but a giant millipede, Arthropleura, roamed around Kentucky hundreds of millions of years ago.
The Arthropleura is thought to be the largest arthropod to have ever walked the Earth. Arthropods are invertebrates with jointed legs such as insects, spiders, millipedes, and crustaceans.
The giant millipede was determined to be 6 feet long and 20 inches wide and may have weighed as much as 520 pounds. Evidence of the giant millipedes had been found in fossilized 300 million-year-old rocks.
Scientists believe that the high atmospheric oxygen levels of 35% during the Carboniferous period led to the growth of the giant arthropods.
Scientists also found evidence of the walking trails or trackways of the Arthropleura in Boyd County in Kentucky. They were able to obtain well-preserved casts which contained evidence of the individual tracks and patterns of the Arthropleura.
From the pattern of the tracks, it was determined that Arthropleura had a minimum of 25 pairs of walking legs. The movement of the arthropod was also established from the tracks.
The Arthropleura is thought to have become extinct as a result of habitat loss and threats from potential predators such as reptiles and amphibians of the Late Pennsylvanian - Early Permian period.
Today, the closest relative of the giant Arthropleura is the tiny 3 mm long pincushion millipede Polyxenida.