Rotten Fish Helps Solve Mystery Surrounding Soft Tissue Fossils

Most fossils are made of hard materials such as bones, shells or teeth, but in rare cases soft tissues are also preserved. How it works sometimes and sometimes not, was still a bit of a mystery.

There are fossils in which pieces of skin, muscle or even an eye have been preserved. Internal organs can also fossilize through minerals. But it works much better with one organ than with the other. How is it possible? That’s what researchers at the University of Leicester wanted to find out.

They got the help of dead fish to answer this question. For two and a half months, they studied the chemical composition of the fish’s foul-smelling decaying innards.

They tried to find out if the risk of being converted by minerals into a fossil was mainly linked to the microenvironment of each organ, or if it was in the tissue itself. As the organs turned out to rot in a kind of soup, the first option was out of the question.

It must be in the difference in the chemical composition of each organ. Especially in the pH value. This explains why, for example, we find the intestines, but never the liver.

Knowing which parts of organisms can and cannot fossilize and what they might look like can help researchers in their search for valuable fossils.

Read more: Decomposing fish help solve the mystery of how soft tissue fossils formed.