Ancient Insects Found in Amber Reveal Evolution of Mites

An international team of researchers have discovered a fly and two mites in a millimetre scale droplets of amber from north-eastern Italy that are 100 million years older than any amber arthropod traced.

"Amber is an extremely valuable tool for paleontologists because it preserves specimens with microscopic fidelity, allowing uniquely accurate estimates of the amount of evolutionary change over millions of years," said corresponding author David Grimaldi, a curator in the American Museum of Natural History's Division of Invertebrate Zoology and a world authority on amber and fossil arthropods.

Amber is the fossilized resin that is mostly produced by myriad plants, tress ferns to flowering trees, but mostly conifers. Till date the oldest record of animals in amber dates to about 130 million years. The new finding breaks the record with an age of 230 million years. They are the first arthropods to be found in amber from the Triassic Period.

The team of German scientists led by Alexander Schmidt, of Georg-August University, Gottingen,  examined 70,000 miniscule droplets of amber they traced in the in the Dolomite Alps of northeastern Italy. They have named two species of mites as Triasacarus fedelei and Ampezzoa Triassica. The ancient gall mites are surprisingly similar to ones seen today.

"You would think that by going back to the Triassic you'd find a transitional form of gall mite, but no," Grimaldi said. "Even 230 million years ago, all of the distinguishing features of this family were there -- a long, segmented body; only two pairs of legs instead of the usual four found in mites; unique feather claws, and mouthparts."

According to the researchers, ancient mites might have fed on leaves that led to their preservation. This finding reveals the evolutionary endurance of the mites.

We now know that gall mites are very adaptable," Grimaldi said. "When flowering plants entered the scene, these mites shifted their feeding habits, and today, only 3 percent of the species live on conifers. This shows how gall mites tracked plants in time and evolved with their hosts."

Though the team had successfully identified the two mites, they had a difficulty in identifying the fly as its body parts were not preserved very well.

"There was a huge change in the flora and fauna in the Triassic because it was right after one of the most profound mass extinctions in history, at the end of the Permian," Grimaldi said. "It's an important time to study if you want to know how life evolved."