A new study by Earth scientists from Yale and the College of the Atlantic has turned up a massive die-off of sharks roughly 19 million years ago.
SciTechDaily has an article about a shark extinction, which took place about 19 million years ago during the early Miocene. A new study published in the journal Science looked at shark diversity over the last 40 million years and found an extinction event that reduced shark diversity by about 90%. In a related Perspective article in Science, the authors add more details.
Nineteen million years ago, sharks nearly disappeared from Earth’s oceans, according to a new study, which provides evidence for a previously unknown mass ocean extinction event. Sharks as a species never recovered from this, the study’s authors say; their diversity today represents only a fraction of what it once was, the data suggest.
Much of what is known about ancient ocean ecosystems is derived from rock and fossil records, which are generally limited to shallow-water deposits and provide only a small glimpse into the ocean-wide history of marine species. Here, using a different dataset — small fossils in global deep-sea sediment cores — Elizabeth Sibert and Leah Rubin provide a new view into changes in the abundance and diversity of one of the ocean’s greatest predators.
Using microfossils in the sediment cores called ichthyoliths — scales and teeth shed from sharks and other bony fishes that naturally accumulate on the seafloor — Seibert and Rubin constructed a record of shark diversity and abundance spanning nearly the last 40 million years.
According to the findings, sharks all but vanished from the record during the early Miocene roughly 19 million years ago, declining in abundance by more than 90% and in morphological diversity by more than 70%. This puzzling extinction event appears to have occurred independently of any known global climate event or terrestrial mass extinction.
