|
Fish out of water
When ancient fish first sprouted limbs and poked their heads out
of murky river deltas to contemplate life on land, they did so in
a subtropical landscape that is now Ellesmere Island in the Canadian
Arctic. On April 6, 2006, Nature article reported that
the 375 –million-year-old fossilized missing link between
fish and limbed land-lubbers was unearthed in June 2004 by American
scientists who had been fossil-hunting in the area west of Grise
Fiord, Nunavut since 1999.
The three-metre-long Tiktaalik roseae had fish-like scales,
fins and gills, but a body structure more like a land-dwelling animal
similar to a crocodile. Its rib structure allowed it to support
itself under the force of gravity in the absence of pressure from
the surrounding water. It had nostrils and eyeballs positioned on
top of its flat head. Leggy appendages with flexible elbow and wrist
structures and the beginnings of digits in the place of fins allowed
the critter to do a push-up, raising its head above the surface
of the fresh water in which it lived. Nudged into the shallows by
larger predators lurking in the deep, Tiktaalik (which
means large, shallow-water fish in Inuktitut) may have used its
newly evolved limbs to venture onto dry land where safety from being
hunted and a buffet of centipedes and millipedes beckoned. This
part-fish, part-terrestrial animal is the missing link between animal
life in the sea and animal life on land.
— Sarah Rogers
|
