Paleontologists have found that 45-million-year-old frog fossils are so well preserved because their skin is mineralized, which provides a new perspective for their adaptation to land. Paleontologists at University College Cork (UCC) in Ireland have unraveled centuries-old mysteries about how some frog fossils preserve their fleshy parts. They found that it was all thanks to their skin.
Image source: A. Pieri (University of Pisa)
Paleontologists Daniel Falk and Professors Maria McNamara, together with scientists from Ireland, Germany and the United Kingdom, have studied frog fossils dating back 45 million years at the Geiseltal site in central Germany. Strikingly, these fossils show the contours of soft tissues throughout the body. The team found that frog fossils are well preserved because of the preservation of skin remnants from ancient times.
The team studied the fossils using high-precision techniques such as scanning electron microscopy, synchrotron radiation X-ray analysis, and infrared spectroscopy. These techniques did not exist at the time of the first discovery of fossils in the early twentieth century.
"The quality of the preservation of the fossilized frog skin is amazing – even subcellular structures such as collagen fibers have been preserved. Daniel Falk, a doctoral researcher and head of the study, said. "The skin of the frog is replicated in the mineral calcium phosphate, which helps it survive for millions of years".
"Its skin is so well preserved that we can even deduce the habitat of fossil frogs," Daniel said. The preserved skin showed an adaptation to prevent dryness, suggesting that these frog fossils actually spent most of their time on land. "
Senior author Professor Maria McNamara said: "Soft tissue fossils often reveal hidden information about animal biology. We found that the skin of the frog fossil was preserved in the same way as the frog fossils found elsewhere in Europe. "
Daniel Falk examines fossilized skin samples from Geiseltal frogs with an electron microscope. Source: Daniel Falk
"This discovery is very exciting because it overturns a scientific view that has lasted for nearly a hundred years. What's more, the repetitive pattern of fossil preservation tells us that frogs evolved a special ability to adapt to dryland life more than 45 million years ago."
This study highlights the usefulness of historical fossil collections and the need to re-evaluate historical specimens using modern technology.
The study was published today in the journal Scientific Reports.
编译来源：ScitechDaily