Preteen tetrapods identified by bone scans
Improved technique suggests large four-limbed Acanthostega were still juveniles
![Acanthostega](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2016/09/090716_sm_tetrapod_feat_free.jpg?fit=860%2C460&ssl=1)
ANCIENT YOUNGSTERS Water-dwelling Acanthostega (museum imagining of full form shown) may have been hanging out in schools of youngsters 360 million years ago.
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.