As revealed by a new study, tens of millions ago, at a time when dinosaurs still roamed the Earth, a day on our planet was much shorter than it is today.
According to scientists, Earth rotated faster than today, 372 times a year, compared to 365 today, revealed mollusk shells from the Late Cretaceous. This means that a day back then lasted only 23 hours and thirty minutes.
The ancient mollusk studied by a group of scientists comes from an extinct and very diverse group known as rudist clams, which grew fast, establishing daily growth rings.
Now, a new study used lasers to take tiny samples of shells and count growth rings more accurately. The previous analysis saw experts use microscopes to try and accurately count the growth rings.
Growth rings allowed researchers to determine the number of days in a year and to more accurately calculate the length of a day on Earth, some 70 million years ago.
The new measurement offers a great amount of data on many important clues not only about Earth but of how the Moon formed and the distance from Earth during the 4.5 billion year history of the Earth-Moon gravitational dance.
The new study also found evidence corroborating that mollusks harbored photosynthetic symbiotes that may have fueled reef construction on the scale of modern corals.
The new data obtained in the research, combined with the rapid growth rate of the ancient species, revealed unprecedented details about how the animal lived and the conditions of the water in which it grew, up to a fraction of a day.
The researchers revealed that the study allowed them to obtain around four to five data points per day, something that is rarely obtained in geological history.
“Basically we can see one day 70 million years ago. It’s quite surprising,” said Niels de Winter, an analytical geochemist at Vrije Universiteit Brussel and the study’s lead author.
Climatic reconstructions of Earth’s distant past usually describe long-term changes that occur on the scale of tens of thousands of years. Studies like this give insight into the change in the time scale of living things and have the potential to bridge the gap between climate and climate models.
In other words, the recent study offers unprecedented insight into the lives of species on a day-to-day basis.
The new chemical analysis of the shell indicates that ocean temperatures were warmer in the Late Cretaceous than previously suggested, reaching temperatures as high as 40 degrees Celsius in summer and more than 30 degrees Celsius in winter. High summer temperatures likely approached the physiological limits of mollusks, the researchers revealed in the new study.
The new study saw experts analyze a single specimen of the Torreites sanchezi mollusk species, which lived for more than nine years on a shallow seabed in the tropics, a place that is now 70 million years later, dry land in the mountains of Oman.
As revealed by Phys.org, during the late Cretaceous, rudists like T. sanchezi dominated the reef-building niche in tropical waters around the world, filling the role held by corals today.
The study was published in Paleoceanography and Paleoclimatology.