Days on Earth Used to Be 30 Minutes Shorter, Ancient Shell Suggests

Scientists do the most amazing things today. A study on a single specimen of fossil mollusk has determined the length of an each day 70 million years ago. The shell is of the species Torreites sanchezi, described as a rudist clam, which makes one wonder what it did that was so rude.

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Like counting the rings of a stump to discern the age of a tree, scientists from the Environmental and Geochemistry Research Group at Brussels University have counted the microscopically thin layers of an extinct mollusk to calculate the length of a Late Cretaceous day. The new paper, published in Paleoceanography and Paleoclimatology, shows that, some 70 million years ago, days were around 23.5 hours long and that the Earth rotated 372 times each year, as opposed to the current 365 days per year.

The overall length of the year hasn’t changed since the Late Cretaceous—a total year consisted of 8,760 hours during the Late Cretaceous, just as a year does today. It’s just that our planet’s spin is getting progressively slower, thanks to the gravitational effects of our Moon. Accordingly, the new research, led by Niels J. de Winter, could improve our understanding of the Earth-Moon relationship over time and even the timing of the origin of the Moon.

Scientists had already figured the length of days back then, but this is another source that confirms their calculations. What’s really amazing how they did it. The fossil shell is not particularly big, and the daily “growth rings” are actually layers no more than 40 nanometers thick. They counted these, and compared the number to seasonal changes in the shell to figure out how many days were in a year. In a fossil. Read more on this study that shows what you can learn by taking a very close look at tiny things at Gizmodo. 

(Image credit: AGU)

Source: neatorama

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