Over 8,000 Iron Age Frog Bones Found in A Ditch Near Cambridge Leave Experts Baffled

Scientists at the Museum of London Archeology (MOLA) were baffled upon finding 8,000 ancient frog and toad bones while excavating a site near the Iron Age roundhouse at Bar Hill, near Cambridge. The team said that the sheer quantity of the bones is all concentrated in one place, which is extraordinary.

The zooarchaeologists collected the bones between 2016 and 2018. They were unsure why the bones were near the 14-meter-long ditch at the side of the roundhouse. They estimated that the bones belong to about 350 amphibians, The Hunts Post reported.

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More Than 8,000 Iron Age Frog Bones Found in A Ditch Near Cambridge, Baffling Experts

Extraordinary Finding of Frog Bones

Despite finding thousands of frog bones at the site, the museum group said that few other amphibian bones had been discovered in the archaeological sites surrounding the areas, not even in those rivers.

MOLA museum experts, who found the surprising and strange discovery using a fascinating detective inquiry, said that finding frog bones on digs was indeed unusual, but finding thousands of them in one place is completely out of the ordinary.

According to BBC News, there have been several theories suggested so far that may somehow be unlikely reasons. One of which is that amphibians were eaten by humans, birds, or other animals. However, the theory was considered highly unlikely since there were no burns, cuts, or bite marks on the bones.

Another theory is that the amphibians may have been attracted to the promise of food in the area, given the evidence that grain processing would have brought beetles and aphids that are known food for frogs and toads.

Scientists also think that it is possible that they could have fallen to the ditch of the roundhouse during migration season while looking for breeding grounds and were unable to climb out. Or they could have died during hibernation as the mud becomes too cold in the winter.

Dr. Vicki Ewens, senior archaeozoologist at MOLA, said that the mystery of the bones in one place is indeed puzzling and unexpected. For now, they are looking for more evidence to understand the mysterious bones fully.

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Fossil Record of Amphibians

Frogs, toads, and salamanders are examples of amphibians that have been already present even during the last Jurassic Period. According to a 1988 paper, the fossils of the amphibian caecilians were very rare, yet the oldest known ones were from the Cenozoic age or about 65 million years ago.

Recent findings of amphibian fossils show that the ancestry of the legless amphibian dates back to the Jurassic period, but at that time, they still had short legs. The rarity of their fossil records is partly due to the amphibian's burrowing habitat and reduced skeleton, that lessen the chances of preservation.

The earliest well-known amphibian was the Ichthyostega, which was found in Greenland and dated back to the Late Devonian period or about 363 million years ago.

During the Paleozoic period, the world saw a great diversity of amphibians, ranging from small legless swimming animals to horned forms. Most amphibians resembled salamanders, although they differ in the details of their skeletal structure. Paleontologists debate how to classify these fossils and how they may be related to living amphibians.