Most scientists believe that sharks came into existence around 400 million years ago. That's 200 million years before the dinosaurs! It's thought that they descended from a small leaf-shaped fish that had no eyes, fins or bones.
But even predators as ancient as sharks have predecessors, and a new study published in the journal American Museum Novitates seems to confirm the identity of a long-suspected shark ancestor—a group of bony fishes known as acanthodians.
The earliest known modern shark may be Mcmurdodus, which is known from mid-Devonian deposits (about 390 million years old) in what is now western Queensland, Australia. On first consideration, this is an astonishingly early date for the origin of modern sharks - actually predating Cladoselache and Antarctilamna.
Today's sharks are descended from relatives that swam alongside dinosaurs in prehistoric times. In fact, the largest predator of all time was a shark called a Megalodon. It lived just after the dinosaurs, 23 million years ago, and only went extinct 2.6 million years ago.
Scientists believe that the earliest sharks were small and elongated, shaped almost like a torpedo, with a very similar dorsal and caudal (tail) fin to today's sharks [22.01].
The earliest shark-like teeth we have come from an Early Devonian (410-million-year-old) fossil belonging to an ancient fish called Doliodus problematicus. Described as the 'least shark-like shark', it is thought to have risen from within a group of fish known as acanthodians or spiny sharks.
Sharks are older than trees and dinosaurs
The earliest evidence of shark fossils dates back as far as 450 million years, which means these creatures have been around at least 90 million years before trees and 190 million years before dinosaurs.
Megalodon sharks were sharks, and not reptiles, and therefore could not be dinosaurs. However, it does bring up an interesting point regarding age. Dinosaurs are thought to have first appeared around 230 million years ago.
Researchers from Curtin University have found evidence a common ancestor of sharks and mammals had the ability to walk on land 400 million years ago, millions of years before the first animals ever put four-feet on the ground.
The earliest megalodon fossils (Otodus megalodon, previously known as Carcharodon or Carcharocles megalodon) date to 20 million years ago. For the next 13 million years the enormous shark dominated the oceans until becoming extinct just 3.6 million years ago.
Sharks are one of the most popular marine species today, but did you know the earliest fossils date around 450 million years? Even more impressive is the elusive, deep-sea Greenland shark which is one of the oldest living species.
Sharks have survived many mass extinction during their presence of 450 million years on Earth. Scientists believe that their ability to repair damaged DNA has helped them survive over the years. Their presence on the planet over millions of years have earned them the title of living fossil.
Worldwide, there are about 400 species of sharks. Of these, around 180 species occur in Australian waters, of which about 70 are thought to be endemic. Sharks occur in all habitats around the Australian coast line, however most are found on the continental slope or shelf, primarily on the bottom.
Fossils have shown us that the ancient ancestors of sharks first arose around 450 million years ago, during the Late Ordovician period. Yet, it wasn't until around 350 million years ago that the first trees arose! That is a full 100 million years later than the earliest sharks! So sharks truly are older than trees!
For the last 150 years, paleontologists have debated the origins of the great white shark. Many believe that they descended from the 50-foot megalodon, also known as the megatooth shark (Carcharocles megalodon ), which is often imagined to be a vastly inflated great white.
Fossils of teeth from shark ancestors date back to about 418 million years ago and scale fossils date back to around 450 million years ago. Yet, the Doliodus problematicus fossil was the earliest confirmed shark ancestor fossil, and it provided a great deal of insight into the anatomy of its family members.
Sharks have roamed the world's oceans for hundreds of millions of years. In that time, many species have barely changed. But some strange sharks are still evolving—and have even learned to walk. Meet the walking sharks.
The First Animals
Sponges were among the earliest animals. While chemical compounds from sponges are preserved in rocks as old as 700 million years, molecular evidence points to sponges developing even earlier.
Cladoselache is regarded as the first "true shark". It lived 380 million years ago and it still retained a few characteristics of its fishy ancestors. It had a fish-like head, seven gills instead of five like most sharks, and its body was longer and less muscular than the sharks we see today.
Internet rumors persist that modern-day megalodons exist – that they still swim around in today's oceans. But that's not true. Megalodons are extinct. They died out about 3.5 million years ago.
The megalodon had a stomach volume of almost 10,000 litres, meaning it would have been capable of eating prey up to 26 feet (8 m) long. While it would have been able to chomp up a modern Orca, this means it could not swallow a T. rex whole like in 'Meg 2: The Trench'.
Mature megalodons likely did not have any predators, but newly birthed and juvenile individuals may have been vulnerable to other large predatory sharks, such as great hammerhead sharks (Sphyrna mokarran), whose ranges and nurseries are thought to have overlapped with those of megalodon from the end of the Miocene and ...
There are two basic types (genera) of shield shrimp, Triops and Lepidurus. Scientists credit Triops cancriformis as the oldest animal species. Other species may not be quite so old, but the natural histories of the species are similar.
Coelacanth – 410 MYA
The Coelacanth is one of the oldest known fish still alive today. There are two species, one living near Africa and the other near Indonesia. The oldest Coelacanth fossils are only 410 million years old, predating dinosaurs, trees, and sharks by a large margin.
There are two main reasons crocodiles survived the asteroid that killed the dinosaurs. First, crocodiles can live for a very long time without food. Second, they lived in places that were the least affected when the asteroid hit Earth.