New signs of early life on Earth have emerged from Dominican amber. Researchers have found the perfectly preserved fossil of a blow fly relative, the first of its kind, embedded in a piece of amber estimated to be approximately 17 million years old.

The specimen was among thousands of amber inclusions studied by an international team of experts led by Dr Pierfilippo Cerretti (Dept. of Biology and Biotechnology 'Charles Darwin', Sapienza University of Rome). It was found to belong to the group of true flies (Diptera) called “Calyptratae”, which includes common and well-known modern-day species such as the tsetse fly, the house fly, blow flies and flesh flies. The group accounts for about 14% of all extant dipteran diversity and is the result of one of the largest evolutionary radiations in Earth’s history.

These insects occupy key roles in terrestrial ecosystems as decomposers, parasites, vectors and pollinators. "It is difficult to conceive a world where we are not surrounded by flies”, emphasizes Cerretti; “which other group of organisms could replace them as decomposers of organic matter?”. “For oestroids (blow flies, flesh flies, bot flies)”, he adds, “the most diverse group within the calyptrates, definitive fossils were entirely lacking". In an article recently published in PLoS ONE, this first oestroid fly fossil is described from amber collected in a mine north-northeast of Santiago (Dominican Republic) and aged at approximately 17 million years old.

The specimen is part of the James Zigras collection housed in the American Museum of Natural History in New York. It was thoroughly examined through CT-scanning, which provided crucial anatomical detail for a correct identification of the specimen. The fossil was then used to calibrate a molecular phylogeny of the calyptrate fly clade. Results indicate that their most recent common ancestor lived around the Cretaceous-Paleogene mass extinction event (ca. 70 million years ago) and that the oestroids originated later, about 50 million years ago.

The massive upheaval of ecological communities that brought to the end of the dinosaur era may have spurred the diversification of these ecologically versatile flies, as happened with mammals, passerine birds and most flowering plants

References: PLOS ONE First fossil of an oestroid fly (Diptera: Calyptratae: Oestroidea) and the dating of oestroid divergences - Pierfilippo Cerretti*, John O. Stireman III, Thomas Pape, James E. O’Hara, Marco A. T. Marinho, Knut Rognes, David A. Grimaldi