In the December 1, 2005 issue of science, Whyte presents an enormous ichnofossil (trackway) from the Lower Carboniferous (~330 m.y.a.) of Scotland, ostensibly the trace of a concomitantly large arthropod. The trackway is believed to be the first fossil evidence of terrestrial locomotion of the Eurypterid, Hibbertopterus. The 6 meter long, almost meter wide track was found in a sandstone bedding plane of a non-marine sequence, and suggests the animal had three appendage pairs of varying length that moved in phase, and moved very slowly. The find is likely to be that of the largest walking arthropod yet to be discovered, and the first evidence of terrestrial locomotion.

The extinct Eurypterids are believed to be the largest of the arthropods to have ever existed. Order Eurypterida appeared prior to the earliest fishes, and varied from a few inches to some six feet in length. They are believed to have been predators during the Ordovician to Permian periods. Eurypterids are also called sea scorpions that migrated and adapted to land-life in the Carboniferous. Some species may have been amphibious, capable of breathing both in water and in air, and some may have injected venom to secure their prey.

Whyte, MA. Palaeoecology: a gigantic fossil arthropod trackway. Nature. 2005 Dec 1;438(7068):576. PMID: 16319874 [PubMed - in process]