What fossilised skin, blood and sperm reveal about ancient life
Preserved soft tissues have helped flesh out our prehistoric knowledge.
The oldest evidence for preserved protein was unveiled today, with researchers in Canada, China and Taiwan reporting collagen – along with haematite from blood – within a 195-million-year-old dinosaur bone in Nature Communications.
Such finds are rare; when an animal dies, usually only the hardest substances in their body are fossilised (if any become fossilised at all). So when researchers uncover a bit of ancient hair or skin, it's a big deal.
Here are a few examples of preserved tissues that got palaeontologists in a tizzy.
Human cancer: 1.7 million years old
A slice of foot bone from a human relative who died in Swartkrans Cave in South Africa shows an aggressive type of cancer called osteosarcoma, according to researchers publishing in the South African Journal of Science last year. The diagnosis shows cancer has roots way back in human evolution.
Sperm: 17 million years old
And not just any sperm, but giant sperm from an ancient species of freshwater shrimp. In the Proceedings of the Royal Society B in 2014, an international team reported the fossil sperm, complete with nuclei that carried DNA, which was found in rock from the Riversleigh World Heritage Fossil Site in Australia in the 1980s.
Uncoiled, the sperm cells were bigger than the male shrimp's entire body length. Studying the fossilised cells along with reproductive organs, the researchers found little difference between modern-day shrimp and their ancient ancestor.
Blood and skin cells: 75 million years old
In 2015, UK researchers were surprised with blood cells and collagen-like structures inside eight bones from Cretaceous-era dinosaurs sitting in London's Natural History Museum. Reporting in Nature Communications, examining the bonds made by the iron in the blood could help explain why dinosaurs switched from being cold-blooded to warm.
Feathers: 130 million years old
This incredible fossil of the early Cretaceous bird Eoconfuciusornis was reported last year in the Proceedings of the National Academy of Sciences. A team in the US and China showed molecular evidence for keratin and melanosomes (which contain pigment) in those feathers, suggesting that ancestors of modern birds were coloured all those years ago.
Nervous system: 520 million years old
This incredibly detailed fossil belongs to the crustacean-like Chengjiangocaris kunmingensis – complete with a long "ropelike" central nerve cord and clusters of nerve tissue called ganglia arranged along it.
Reporting last year in the Proceedings of the National Academy of Sciences, a team from China, the UK and Germany said the fossil might could help decipher the evolution of nervous systems in modern-day animals.
Muscle imprint: 570 million years old
This imprint of a soft-bodied creature called Haootia quadriformis, which shared ancestry with modern sea anemones, jellyfish and corals, was found in Newfoundland, Canada in 2008.
In 2014, researchers in the UK and Canada published evidence of fibres arranged in parallel bundles in Proceedings of the Royal Society B, suggesting that even more than half a billion years ago, creatures used a muscle – or muscles – to move.