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  • 7. 1: Introduction to the Oceans - Geosciences LibreTexts
    When the Earth was formed 4 6 billion years ago, it would never have been called the Blue Planet There were no oceans, there was no oxygen in the atmosphere, and no life But there were violent collisions, explosions, and eruptions In fact, the Earth in its earliest stage was molten
  • South Africa’s great white sharks are changing locations . . .
    South Africa is renowned for having one of the world’s biggest populations of great white sharks (Carcharodon carcharias) Substantial declines have been observed, however, in places where the
  • 400 Million Years of Shark Evolution - ThoughtCo
    The First Sharks We don't have much in the way of direct evidence, except for a handful of fossilized scales, but the first sharks are believed to have evolved during the Ordovician period, about 420 million years ago (to put this into perspective, the first tetrapods didn't crawl up out of the sea until 400 million years ago)
  • How paleontologists are using fossilized shark teeth to date . . .
    Sharks have ruled the Earth’s oceans for 400 million years and recent research on fossilized shark teeth has led to the discovery of an innovative method for dating ancient sediments
  • The man who keeps finding new species of shark - BBC News
    Most people have heard of great white, hammerhead and tiger sharks but there are many other species - and every year a number of new ones are discovered One enthusiast has, so far, identified 24
  • Sharks | International Plan of Action for Conservation and . . .
    Sharks and their relatives – the batoids and chimaeras – comprise the chondrichthyan fishes, a group of more than 1 100 species, of which more than 400 are sharks Most of these species have slow rates of growth, late age-at-maturity and low fecundity compared with bony fishes
  • Sharks, Fossils, and Caves: Secrets Revealed at Mammoth Cave
    More than 40 different species of fossil sharks and relatives have been identified from Mammoth Cave specimens in the past 10 months and the fossil survey continues Among this fossil shark assemblage, there appears to be at least six fossil shark species that are new to science


















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