Why some animals become fossils and others disappear
Keystone-SDA
The decisive factor is the body of the animals themselves, the research team shows in a new study.
The size and chemical composition of an animal can significantly influence whether it will be preserved as a fossil for millions of years, as the University of Lausanne (Unil) announced on Thursday.
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According to the study published in the scientific journal Nature Communications, larger and protein-rich animals have a significantly higher chance of becoming fossils. Large arthropods – animals with jointed legs such as insects, crabs or spiders – are therefore more likely to be fossilised than smaller, simply built animals such as certain flatworms or other worms that live in water.
“It is therefore quite possible that some organisms could never be preserved in fossil form and that we will therefore never be able to observe them at all or only with great difficulty,” explained Nora Corthésy, lead author of the study.
Decomposition in the laboratory
Fossils are much more than just bones, the researchers emphasised. Some of the most impressive finds contained the remains of soft tissue such as muscles, intestines or even brains. However, why only some animals or organs are so well preserved has been a mystery until now.
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To get to the bottom of this mystery, the research team had various animals, including shrimps, snails, starfish and worms, decomposed in the laboratory in a controlled manner. They analysed how the chemical environment of the animals changed during the decomposition process. It was found that larger and protein-rich animals produce a low-oxygen environment more quickly. These conditions inhibit decomposition and promote processes that are important for fossilisation.
Adapted from German by DeepL/ac
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