Ancient, icy animal burrows

The Allan Hills of Antarctica’s Victoria Land are not only famous for a Martian meteorite that made a splash in 1996 – bearing what some interpreted as evidence of microbial life from the red planet. The area also is noted for terrestrial fossils dating back millions of years. Scientists say they have uncovered 245-million-year-old fossilized animal burrows – 15 million years older than fossilized bones found in the area.

Natural casts of the burrows formed when a river overflowed and filled the cavities with silt, which hardened, according to Christian Sidor, a University of Washington paleontologist who led a team of researchers reporting the find. The largest burrow segment is some 14 inches by 6 inches. And while the researchers say they’ve found no bones, the burrow casts carry tracks that the residents made as they wandered in and out of their homes.

Similar burrows with bones have cropped up in South Africa, leading the team to posit that the residents in the Allan Hills neighborhood may have been small lizard-like creatures known as Procolophonids, or perhaps early mammals dubbed Thrinaxodons.

From a climate standpoint, while Antarctica – then joined at the hip to Africa – would still have been cold, it was largely ice free, researchers note. So the burrows would have afforded protection from the elements. The results appear in the June issue of the Journal of Vertebrate Paleontology.