The fossilized traces show crescent-shaped prints left by the creature's outer limbs and a sinuous curve carved by a thick dragging tail.
With at least three pairs of appendages of different lengths, the track maker most likely belonged to the
Hibbertopteroid eurypterid species.
"To my knowledge, this the largest terrestrial trackway of a walking arthropod (a group that includes insects and crustaceans) to be found so far. Most importantly, it shows that Hibbertopterus could survive out of water, at least briefly," Whyte told Discovery News.
Indeed, the only truly terrestrial arthropods that approached two meters in length were the arthropleurids, giant centipedes and millipedes from 360 to 280 million years ago. However, known individual trackways are up to about one meter in length.
Analysis of the track revealed that the creature wandered the rivers and swamps of prehistoric Scotland with a lumbering, slow motion.
This, combined with the dragging of the tail, "indicates that the animal was buoyant and that it was probably moving out of water," Whyte said.
The finding suggests that our earliest land-walking ancestors were confronting giant, slow moving water scorpions at the time they left their aquatic environments to colonize the land.
We don't known whether the fearsome creature, which fed mostly on smaller prey such as water fleas, would have presented much threat to our four- limbed ancestors.
"Little is known about the life habits of these large hibbertopteroid water scorpions," Derek Briggs, a top paleontologist at Yale University and director of the Yale Institute for Biospheric Studies, told Discovery News.
"This is certainly the largest trackway of an arthropod on land, although the shuffling gait indicates that the animal was not in its natural habitat. It is a remarkable discovery — the first good evidence that hibbertopteroids were able to walk out of water, even if under some duress," Briggs said.
