Prehistoric mite found hitchhiking on spider’s back

These three-dimensional images of a 50-million-year-old spider show a tiny mite, only 176 micrometres long, hitching a ride on its back.

Researchers from Manchester University believe it is the smallest arthropod fossil ever to be scanned using x-ray computed tomography (CT) scans. Their study was published in the Royal Society Journal Biology Letters last week.

The mite was trapped inside Baltic amber, or fossil tree resin.

The study shows that the behaviour of phoretic, or hitchhiking, animals has been evolving for at least 50 million years.

Dr David Penney, one of the study’s authors from the Faculty of Life Sciences said “CT allowed us to digitally dissect the mite off the spider in order to reveal the important features on the underside of the mite required for identification.

“The specimen, which is extremely rare in the fossil record, is potentially the oldest record of the living family Histiostomatidae.”

The images may encourage more research on phoretic behaviour.

Dr Richard Preziosi, a Manchester biologist, said, “The fact that we now have technology that was unavailable just a few years ago means we can now use a multidisciplinary approach to extract the most information possible from such tiny and awkwardly positioned fossils”

Dr Jason Dunlop, from Humboldt University in Berlin, also worked on the study.

He added, “Work like this is breaking down the barriers between palaeontology and zoology even further.”