A death pit containing 8,000 frog and toad bones dating back at least 2,000 years has archaeologists in England baffled as to how the shattered amphibian corpses got there, with ideas ranging from cold death to a nasty swoop to a disease killer.
This is an enigmatic and unexpected find that we are still trying to fully understand,” said Vicki Ewens, senior archaeozoologist at the Museum of London Archaeology, in a statement. “This accumulation of frog debris may have been caused by a number of factors, potentially interacting over a long period of time.”
The team found the bones at an ancient settlement at Bar Hill in Cambridgeshire, England, dating from around 400 B.C. and 70 AD. The bones come from at least 350 individual frogs and toads, and the ditch where they were found is next to a roundhouse — a circular-plan house, archaeologists said in the statement. There is no evidence that the frogs and toads were eaten by humans or other animals.
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Researchers have several ideas to explain how the skeletal remains ended up in the ditch. One possibility is that during their spring breeding season, large numbers of frogs and toads moved en masse in search of water bodies to mate, only to fall into a ditch from which they could not escape, the archaeologists said in the statement.
Another possibility is that it is contagious virus infected and killed these amphibians at about the same time. A similar scenario played out in the 1980s when many frogs in the UK became infected with a ranavirus, archaeologists noted in the statement.
The amphibians could also have died in a particular cold winter. Another possibility is that beetles and aphids (a group of sap-sucking insects) swarmed from the roundhouse to the grain, and their presence attracted frogs and toads, which ate them; over a period of time and the frogs may have died in the ditch because they couldn’t climb out.
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A number of scholars unconnected to the research were excited by the discovery.
“This is a fascinating find. There is no way of knowing if a pathogen/disease was to blame, but the suggestion is [that] The frogs may have fallen into the roundhouse ditch during migration and were unable to climb out, which seems reasonable as the ‘best guess’,” Roland Knapp, a research biologist at the University of California Santa Barbara’s Marine Science Institute, told Live Science in a E-mail Knapp has researched and written extensively on amphibians.
“I think this news is exciting and fascinating,” Jamie Voyles, associate professor of biology at the University of Nevada Reno, told Live Science in an email. “Even today, it can be really difficult to determine the cause(s) of mass mortality events. Having said that, I would say that infectious diseases are a possibility that could be considered and investigated.”
Archaeologists were excavating at Bar Hill in advance of a construction project to widen a highway in the area. The excavations have been completed and analysis of the artifacts is ongoing. A spokesman for the Museum of London Archeology said there were no plans to carry out DNA analysis of the frog and toad bones. Ewens was unable to respond to Live Science at the time of publication.
Originally published on Live Science.
https://www.livescience.com/amphibian-death-pit-iron-age-village Amphibian ‘death pit’ filled with 8,000 bones unearthed in Iron Age village