Scientists Puzzled by Ancient Shark Near-Extinction Event
by Theodore B. Morrison, age 13
Sharks are one of the most feared predators on the planet, and while they looked the part, that didn’t protect the population from near-extinction events throughout history. A recent study shows that a large portion of sharks died spontaneously within the span of 100,000 years from start to end, eons ago. There have been different observations and possible conclusions made by scientists.
The event in question occurred 19 million years ago, predating human existence. It is believed to have killed nearly 90 percent of the shark population worldwide. Before the extermination, there was an age of death for many other ocean species, which was followed by the sharks’ long-standing domination over the sea. The ensuing near extinction of the sharks continues to puzzle scientists.
Elizebeth Sibert, paleobiologist and oceanographer at Yale University, was the scientist looking into this event. She observed that sharks with a particular bone shape were targeted specifically. “The project came out of a desire to better understand the natural background variability in these fossils,” she said.
She shifted through sediment to sort fish teeth and shark scales according to shape and age. While doing so, she and her team recognized the quick and drastic drop in the number of shark scales compared to the fish teeth. This led to her discovering the mass extinction of many shark species.
Sibert is still making queries into the event and pursuing answers to the questions already asked. Answers to the queries made could be privy to modern day problems, such as ocean warming and overfishing. Which have caused an estimated 70 percent reduction in the shark population. The answer could help prevent such an event now.
Scientists continue to ponder the question of what caused this abrupt decline in the number of sharks. This mass extinction of sharks is an intriguing topic, the journey to find answers will be an interesting one for sure.
[Source:
ScienceNewsforStudents
; nytimes.com]