Sticky situation reveals part of our evolutionary history

During the Eocene period, the swamp may have scared away most critters. Those that traveled close enough were hit by a wall of methane gas. Unlucky animals died, but fortunately for us, their fossils were preserved almost perfectly.

One dead animal in particular wandered too close and ended up at the bottom of this anoxic lake. Layers of sediment slowly squashed the sample, forming a fossil. Forty-seven million years later, our fossil was excavated, embedded in shale.¹ But careless handling caused an unfortunate break in the stone, which separated the two halves of this fossil for many years. The two halves ended up with different owners, one of whom doctored his find to make it look more impressive!

Controversy surrounds this fossil because of its astounding completeness. In addition to the bones, this fossil contains an imprint of the animal's soft tissue, including outlines of its fur and digestive tract. Since the fossil contains so much information, researchers are eager to classify it correctly. Scientists are debating the relationship of this new species, Darwinius massilae, to early primates.

The first camp believes the fossil was a member of the early Haplorhines, which were the ancestors of anthropoids such as monkeys, apes, and humans. The fossil would fit into this group because it lacks certain key grooming features. The second camp wants to place this fossil with the adapiform group, which includes the ancestors to modern lemurs and lorises.

We're in constant search for the missing link between Homo sapiens and ancient primates. With this find, we've got one more piece of the evolutionary jigsaw puzzle.

¹Laursen, L. Reunion of fossil halves splits scientists. Nature. 19 May 2009. http://www.nature.com/news/2009/090519/full/news.2009.494.html
²Franzen, J. L. et al. PLoS ONE. 2009. doi:10.1371/journal.pone.0005723