Fossil reveals world's oldest genitals

Fossil reveals world's oldest genitals
16:30 20 September 03 - New Scientist

The discovery of the world's oldest genitals proves that little has changed over the last 400 million years - at least for daddy-long-legs.

Fossils of harvestmen arachnids (Opiliones) have been found by palaeontologists in an ancient rock at Rhynie near Aberdeen in Scotland. Preserved within a male is a penis two-thirds the length of his body, and on a female there is a long egg-laying organ known as an ovipositor.

The organs are remarkably similar to those in modern-day species of harvestmen. Dubbed daddy-long-legs along with crane flies, harvestmen are not formally classified as spiders because they do not spin webs.

Between 400 million and 412 million years ago, Rhynie was 28° south of the equator on the ancient continent of Laurussia.

Hot springs like those in Yellowstone National Park in the US deposited silica, trapping animals and plants. Since their discovery in 1912, the silica formations have yielded a series of world firsts in well-preserved arthropods. This week a team led by Jason Dunlop from Humboldt University in Berlin, Germany, will tell a conference in Aberdeen about the harvestmen fossils.

As well as genitals, the fossils have the oldest known arachnid respiratory system, suggesting harvestmen's ancestors had long since crawled out of the sea and learned to breathe. Today's harvestmen also possess a very similar pair of large, branching trachea.

Rob Edwards, Edinburgh