The day was shorter and the full moon was big. The clams revealed how long the day was in the days of dinosaurs

24 hours a day seems to us all something extremely natural. Our daily cycle is adapted to such length of day and night and we would probably feel even a slight change. But did the day on Earth always have 23 hours and 56 minutes? Mussels say no. Thanks to the petrified shells from 70 million years ago, scientists were able to determine that when the mussels hiding in them lived a day lasted only 23.5 hours. Thus, it can be said that when dinosaurs walked the Earth, the year lasted 372 slightly shorter days.

The fossil that provided scientists with detailed information is the shell of the already extinct clam species. The researchers obtained from the fossil a super-thin core, which says a lot about the conditions in which the animal lived. Cross-section through the crust, like rings in a cross-section of a tree, tell us a lot about the rhythm that shaped the mussel's life.

In addition to seasonal changes, the shell also noticed differences in the growth rate in the microscale, associated with the fact that during the day the growth was faster and at night slower. This indicates that molluscs of this type shared their shells with bacteria that, like plants, can convert solar radiation into sugars.

When the researchers counted all these individual layers, they realized that for each year (and the year lasts the same since eons) there were 372 days. For everything to be correct, and during the year an additional 6.75 days could be stuffed, the day would have to last 23.5 hours.

The day was shorter and the full moon was great

The above information, however, is not only interesting for lovers of mussels or for biology lovers. This mussel fossil tells us much more. The Earth's rotation rate is directly related to the distance between Earth and the Moon. The slower the Earth rotates, the further away the Moon flows from it.

Of course, for astronomers, slowing the Earth's rotation is nothing new. So is the moving away of the moon. Astronauts from the Apollo mission have placed reflectors on the moon so that you can send laser beams from Earth, which are reflected from them, and in this way measure the distance between us and our natural satellite. Thanks to this, we know that the moon is 4 cm away from Earth every year. However, this pace could not always be the same. If that were the case, then 1.5 billion years ago the Moon would be in the same place as Earth, and yet we know that the Moon was formed 4.5 billion years ago. So initially he had to move far more slowly from Earth.

Scientists need more of these fossils and much older to determine changes in the rate at which the moon is moving away from Earth. Only by comparing a few points in time will we be able to determine how the length of the day on Earth and the rate of escape of the Moon have changed. Therefore, we have nothing else to do but look for new, even older petrified shells.

The results of the study were published in a scientific article that appeared in the journal Paleoceanography and Paleoclimatology.

The day was shorter and the full moon was great. The clams revealed how long the day was in the days of dinosaurs