First Land Animals Are Older Than Expected

I found this discovery to be very interesting. Science has pretty well settled that life began in the sea, and after millions of years some of those marine animals developed legs and took to living on the land. You could call them the first land-walkers.

Scientists had theorized that the first fully-developed land animals appeared less than 375 million years ago. That's because of an animal called the Tiktaalik that lived about 375 million years ago. The Tiktaalik had features that are in between fish and true tetrapods (four-legged animals). But it now looks like some tetrapods may have developed much earlier.

Rocks from a disused quarry in southeast Poland contain the footprints of what may be among the earliest land-walkers. Polish and Swedish scientists have examined the footprints and determined that they come from fully-developed vertebrate tetrapods. The surprise came when they dated the prints, and found they were about 398 million years old.

This would push back the development of land vertebrates to over 400 million years now -- millions of years older than previously expected. The scientists said the animals were probably crocodile-like in appearance and lived an amphibian-like existence (although true crocodiles and amphibians did not develop until millions of years later).

Several pathways of the footprints have been discovered at the Zachelmie Quarry in the Holy Cross Mountains in Poland.