230 Million Year Old Arthropods Found Preserved in Amber

August 30, 2012

Science

amber-preserved-arthropods-triassic

Arthropods from the Triassic period have been discovered preserved in amber. They are 100 million years older than previous amber inclusions. The two mites and one fly were found in millimeter-scale droplets of amber from northeastern Italy.

Researchers published their findings in the journal Proceedings of the National Academy of Sciences. Arthropods are invertebrate animals including insects, arachnids and crustaceans. The specimens were preserved with microscopic fidelity, allowing the estimation of the amount of evolutionary change over millions of years. Arthropods are more than 400 million years old, but before now the oldest record of these animals in amber dates to about 130 million years, in the Cretaceous period.

arthropods-in-amber

Photomicrographs of Diptera specimen in Dolomite Triassic amber, (A) Entire specimen with dissociated appendages. (B) Head, detail. (C) Detail of antenna and adjacent leg, showing oval sensory area, possibly Johnston’s organ. (D) Detail of dissociated distitarsus. (E) (F) Dissociated legs

The amber droplets range between 2 to 6 mm in length, were buried in the Dolomite Alps of northeastern Italy and excavated by Eugenio Ragazzi and Guido Roghi of the University of Padova. Over 70,000 droplets were screened for inclusions by a team of German scientists led by Alexander Schmidt, of the Georg-August University in Göttingen.

Two of the specimens are a new species of mites, Triasacarus fedelei and Ampezzoa triassica. They are the oldest fossils of a group called Eriophyoidea, which has about 3,500 living species, all of which feed on plants and sometimes form abnormal growth called galls on their bodies.

amber-droplets

T. fedelei and A. triassica fed on a now extinct conifer, but 97% of today’s gall mites feed on flowering plants. These mites existed before the appearance of flowering plants. The mites seemed to have evolved and endured even when flowering plants entered the environment. The fly couldn’t be identified because some of its body parts weren’t well preserved.

There was a huge change in flora and fauna in the Triassic, because it was right after one of the most acute extinction pulses in the geological time record, the Permian-Triassic extinction event, which occurred 252.28 Ma. This could help elucidate how life continued to evolve.

[via PNAS]

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