According tomedia New Atlas, time is not as constant as we think. The speed at which the Earth spins is changing, which affects the number of hours in a day and the number of days in a year. Now, palaeontologists have managed to accurately measure the rotation and rotation of the earth for a week during the time of the dinosaurs – thanks in all to a mollusc fossil.
Although with age and busyness, sometimes the time passes faster, it is well documented that the days are actually getting longer, though not many. In fact, today is about 1.8 milliseconds longer than on the same day 100 years ago. That’s because the moon’s orbit is slowly moving away from Earth, moving about 3.8 centimeters a year, and changing tidal forces are slowing the Earth’s rotation. Of course, a slower rotation means a longer time.
Previous studies have shown that about 1.4 billion years ago, a day lasted only 18 hours. That’s because the moon is closer, making the earth spin faster. In the new study, the team was able to accurately measure the length of a day about 70 million years ago. This happens to be the peak of the dinosaur rule, about 5 million years after the apocalypse destroyed about three-quarters of earth’s life.
Specifically, the team determined that there were only 23.5 hours a day. And because of the reduction of half an hour per day, more time can be accommodated in a year – about 372 days a year.
So how do scientists solve this problem? By studying the rapid growth of ancient molluscs. Torreites sanchezi is a bivalve, a clam creature that lived in the ocean until a historic asteroid hit. These creatures grow very quickly, adding several new layers of masonry to their shells every day. Scientists can study these “year wheels” to understand the environmental clues of molluscs at each stage. It is similar to trees or rock layers on the ground, but changes only take hours, not years or thousands of years.
“We have about four to five data points a day, which is almost unprecedented in geological history,” said Nils Derwent, lead author of the study. We can basically look at the day 70 million years ago. It’s amazing. “The team focused its research on a specific specimen that appeared to have lived in the shallow tropical seabed for about nine years. They used lasers to take tiny shell samples and analyze the trace elements. This tells them about the temperature and chemical properties of the water that bivalves live in, and how they change over time.
The analysis showed that the composition of the shell changed layer by layer, and the growth of the day was faster than that at night. The researchers were able to see groups of layers that were repeated with clear patterns, indicating that the seasons were changing. By carefully calculating these layers, the team determines that there are 372 days per annual cycle. They also found more details about the world in which these creatures live. For example, ocean temperatures reach up to 40 degrees C (104 degrees F) in summer and 30 degrees C (86 degrees F) in winter.
The study was published in the journal Paleamandandandolimology.