Ancient shark teeth helping solve mystery of Earth’s climate history

The sharp pointed enamel of sand tiger sharks, hunted within the waters off the Antarctic Peninsula some tens of tens of millions of years in the past, at the moment are serving to remedy the thriller of why the Earth started shifting from a greenhouse local weather that was hotter than at the moment towards cooler icehouse situations, reviews information company PTI.

A examine by the College of California mentioned that there’s geologic proof that each the Drake Passage, which is the water between South America and the Antarctic Peninsula, and the Tasman Gateway, between Australia and East Antarctica, widened and deepened throughout this time as Earth’s tectonic plates moved.

The broader and deeper passages have been essential for the ocean water to mingle and the Antarctic Circumpolar Present — which flows round Antarctica at the moment — to type. The present traps chilly waters within the Southern Ocean and helps hold Antarctica chilly and frozen, the examine revealed.

By finding out the chemistry preserved in these shark enamel, College of California discovered proof of when the Drake Passage opened, which allowed the waters of the Pacific and Atlantic oceans to combine, and what the water felt like on the time. The temperatures recorded in shark enamel are among the many warmest for the ocean within the Antarctic area and so they confirm local weather simulations with excessive atmospheric carbon dioxide concentrations.

Oxygen captured in very sharp enamel

Sand tiger sharks have sharp enamel that protrude from their jaw to understand their prey. Over a lifetime, it sheds 1000’s of enamel as new ones develop. The chemistry of every tooth preserved there over tens of millions of years is encoded with essential environmental info.

The enamel from Seymour Island bear testimony that the Antarctic waters – no less than the place the sharks lived – stays hotter longer than scientists had estimated.

One other clue comes from the ingredient neodymium, which absorbs and replaces different parts within the outer enameloid of the tooth throughout early fossilization. Every ocean basin has a definite ratio of two totally different neodymium isotopes based mostly on the age of its rocks. The ratio within the shark enamel permits the researchers to detect the sources of the water the place the shark died.

The neodymium composition wouldn’t change underneath splendid situations, consultants mentioned. Nonetheless, if neodymium composition does change in fossil enamel over time, that signifies modifications in oceanography.

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