Sharks have roamed on the face of the Earth for more than 400 million years and have recorded history, too, claimed the National Science Foundation in its report published on February 2, 2021.
A new report by The Conversation establishes the same claim by the researcher, Sora L Kim herself, and argues that the now-extinct Sand Tiger Shark species Striatolamia macrota used to swim through the waters around the Antarctic Peninsula.
Now, its remains of exquisitely preserved fossil teeth are left on Seymour Island near the tip of the peninsula, which has stories to narrate.
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Sora L Kim and her fellow co-researchers studied these shark teeth and found proof of when the dark passage opened. This opening resulted in the mixing of the Atlantic and the Pacific waters.
These shark teeth bear a very warm temperature, one of the Antarctic water’s highest held. Moreover, it also verifies climate simulations with elevated atmospheric carbon dioxide concentrations.
Michael Jackson, acting head of Antarctic Sciences Section of the National Science Foundation, said, “The results of this work are exciting as they integrate Shark paleontological studies, geochemical analyses for environmental reconstruction, and novel global climate model simulations to look at the timing and depth of the Drake Passage opening.”
Sora Kim and the others published a paper writing about these findings titled “Probing the Ecology and Climate of the Eocene Southern Ocean With Sand Tiger Sharks Striatolamia macrota,” published in the journal Paleoceanography and Paleoclimatology, which is a platform for publication of new empirical findings on Earth’s past climate and environments from the Precambrian to modern analogs.
Sand Tiger Sharks have very sharp teeth so that they can grasp their prey. Moreover, a single Shark has hundreds of teeth in multiple rows. A Shark in its lifetime sheds over a thousand teeth and grows new ones.
“Important environmental information is encoded within the chemistry of each tooth and preserved there over millions of years,” writes Kim.
She elaborated that like the presence of enamel in human teeth, the outer layer of Shark’s teeth is also made of an enameloid hydroxyapatite. It consists of oxygen atoms from the water the Shark lived in.
By investigating the oxygen found in the teeth, one can know the temperature and salinity of the water in which the Shark lived.
The fossil teeth from Seymour Island show that the Antarctic water; at least where the Sharks lived – stayed warmer for a longer duration than scientists had estimated or expected.
The researchers studied around 400 Shark teeth from Seymour Island; From all ages of Shark – juvenile to adult; from individuals living between 45 million to 37 million years ago, told Kim.
The results were rather surprising. The big size of the teeth suggests that the size of the ancient Antarctic sand tigers was bigger than today’s sand tiger shark, Carcharias taurus, which can grow to about 10 feet long.
Finally, Kim concludes that the fossil of Sand Tiger Shark teeth provides the primary chemical evidence of water flowing through the Drake Passage and coincides with tectonic evidence. She believes that the early timing of the Drake passage and the late cooling effect may indicate some complex intricacies of earth systems that impacted climate change.
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