An international team of scientists working in Italy have found the oldest samples of arthropods preserved in amber — a finding that is 100 million years older than previous fossilized samples. The insects, a fly and two mites, are the first ever to be discovered from the Triassic era. The group's findings will help biologists gain a better evolutionary understanding of these organisms and the time periods within which they developed.
Amber droplets can be a goldmine for paleontologists. Even a millimeter sized droplet can contain extremely well preserved specimens of organisms that lived eons ago — specimens that can be observed with microscopic fidelity. Globules of fossilized resin can range in age from the Carboniferous era (about 340 million years ago) to about 40,000 years ago, and were produced by plants like tree ferns, flowering trees, and conifers.
The amber droplets, which are only 2-6 millimeters long, were discovered buried in the Dolomite Alps of northeastern Italy. Paleontologists working there were able to uncover about 70,000 droplets — all of which were screened for signs of preserved life.
Paleontologists suspect that arthropods, a class of organism that includes insects, arachnids, and crustaceans, have been around for at least 400 million years.
Two of the arthropods are a new species of mites — members of an extremely specialized group that fed on plants and sometimes formed an abnormal growth called "galls." Paleontologists were surprised to see how similar these mites were to ones still alive today. It's thought that the mites fed on the leaves of coniferous trees that eventually preserved them. What this indicates to the scientists is that mites are a highly adaptable species, able to shift their feeding habits; today, only 3% of mites feed on conifers — yet they've remained largely unchanged over the course of 230 million years.
The fly could not be identified, outside of its antennae, on account of poor preservation in the amber. But what's clear is that flies existed at the time of the Triassic — offering paleontologists hope that they'll eventually be able to find a better preserved specimen.
You can read the entire study in PNAS.
Images: University of Göttingen/A. Schmidt.