Improved technique suggests large four-limbed Acanthostega were still juveniles
Photo courtesy of Jennifer Clack
Better bone scanning of fossils offers a glimpse of preteen life some 360 million years ago.
Improved radiation scanning techniques reveal accumulating growth zones in chunks of four fossil upper forelimb bones from salamander-shaped beasts called Acanthostega, scientists report online September 7 in Nature. Vertebrate bones typically show annual growth zones diminishing in size around the time of sexual maturity. But there’s no sign of that slowdown in these four individuals from East Greenland’s mass burial of Acanthostega, says study coauthor Sophie Sanchez of Uppsala University in Sweden. They were still juveniles.
The bones came from tropical Greenland of the Devonian Period. Aquatic vertebrates were developing four limbs, which would serve tetrapods well when vertebrates eventually conquered land. This mass die-off doomed at least 20 individuals, presumably