The ocean covers around 70 percent of the ocean's surface, so why did so many animals leave the sea and try for a life on land all those millions of years ago? The why of that question is still up for speculation, but the "how" became somewhat clearer in light of the recently discovered fractional remains belonging to a 375 million year old fish sharing the physical characteristics of land animals, the Washington Post reported.

Previously, scientists believed the transition to land was primarily spurred by the presence of strong front fins (which would eventually become limbs), and that back limbs evolved within land animals. In this fish species, known as Tiktaalik roseae, powerful hind fins were already solidly in place, even though it was still considered a fish. The discovery could mean that front and back limbs developed in fish first.

"These are four-wheel-drive animals, not just front-wheel-drive only," said study author and paleontologist Ted Daeschler, referring to the species' movement patterns.

Even though Tiktaalik had land-like features, its mobile hind fins enabled it to crawl in the shallow waters it inhabited.

"The size of the pelvic girdle, the region that holds the fins, was as big as the region that holds the front fin," he said. "That was not what we have predicted."

Still, it would take another ten million years after the Tiktaalik fossil lived before the first animals would official make the switch to land. Described as a "clunky, salamander-like creature" by the Post, the species was still largely dependent on the sea.

When the Tiktaalik fossil was first discovered in 2004, its "mosaic" of physical characteristics, as one scientist described them, caused quite the stir within the scientific community. An upper half containing an alligator-like head, a moveable neck, limb-resembling front fins -- all covered in gills and scales -- left the to-be discovered second half to the imagination. A few years ago, the bottom portion was finally excavated, forcing evolutionary scientist to rethink the narrative of sea-to-land transition.

For the full study, click here.