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200
First sharks appeard on Earth
There is not much in direct evidence to know when the first shark first appeared, except for a hand full of fossilized scales, but scientists believe they have evolved during Ordovician period ,about 420 million years ago, -
210
Begining to evolve
This early shark, Cladoselache, was fairly small, and it had some odd non-shark-like characteristics, such as a lack of scales, and a complete lack of "claspers", the sexual organ by which male sharks attach them selves ( which stansfers sperm to)the female. -
250
Later during the Ordeovician period
After Cladoselache, the most important prehistoric sharks of ancient times were Stethacanthus, Orthacanthus and Xenacanthus. Stethacanthus measured only six feet from snout to tail but already boasted the full panoply of shark features--scales, sharp teeth, distinctive fin structure, and a sleek, hydrodynamic build. What set this genus apart were the bizarre, ironing-board-like structures atop the backs of males, which were probably somehow used during mating. The comparably ancient Stethacanthu -
300
During Middle Cretaceous Period
About 100 million years ago the Cretoxyrhina (about 25 feet long) and Squalicorax (about 15 feet long) would be recognizable as "true" sharks by a modern observer. There is evidence of this from direct tooth-marks that Squalicorax preyed on dinosaurs that got into its habitat. -
320
The Devonian Era - 400 MYA)
Over 400 million years ago, innumerable species of bony fish and marine organisms inhabited the Earths seas. The Chondrichthyes evolved a truly unique skeleton composed almost completely of cartilage. Divergent evolution began to further separate the Chondrichthyans from the primitive fish, creating an array of beings that would come to be known as the progenitors of all shark species (Bonaparte, 1838). -
400
Mesozoic Era
Sharks during this era kept a low profile because of intense competition from aquatic reptiles. The most successful shark was the Hybodus,which was built for survival: is had 2 types of teeth, sharp for eating fish and flat for grinding mollusks, as well as a sharp blade jutting out of its dorsal fin to keep other predators at bay. The cartilaginous skeleton of Hybodus was unusually tough and calcified, explaining this shark's persistence both in the fossil record and in the world's oceans, whic -
500
100 Ma
Modern sharks started to appear. This is from them evolving to survive the new enviornment. -
May 7, 600
Carboniferous Period
Stethacanthus was an odd, dogfish-sized shark of the Carboniferous Period, about 320 million years ago. The brush-like dorsal fin with enlarged denticles on its flattened top and corresponding denticled patch on top of its head have generated much speculation about their possible function. -
May 2, 1000
Megalodon (60 MYA)
During the Paleozoic Era the shark known as the Megalodon was one of the most famous prehistoric sharks of this era. It was an adults specimen that measured 70 feet from head to tail and weight as much as 50 tons. This shark feasted on everything from whales, dolphins, and seals to giant fish and giant squids. Know one knows exactaly why they became extinct, but the best possible reasons are from climate change to dissapearence of its prey. -
May 7, 1040
Jurassic and Cretaceous periods
These 2 periods where the begining or the rise of modern day sharks. These periods made a huge diversity of new forms and lifestyles because of the "Jurassic Explosion" and this happened nearly 200 million years ago. From fossils we have today shows that most ancient sharks that survived neoselachian lineages are the cow and frilled sharks. Cow shark fossils characteristics show cockscomb-shaped lower teeth, dating as far back as the early Jurassic Period, about 190 million-years ago. -
May 2, 1300
Jurassic Explosion (100 MYA)
Beginning approximately 100 million years ago, marked the emergence of thousands of shark that slowly evolved. Around 65 to 60 million years ago, the white shark, Carcharodon carcharias arrived. -
Todays Sharks
During the millions of years of evolution, the present day Chondrichthyes have developed some of the most sophisticated hunting systems ever known . The success of the Chondrichthyes as predators is largely due to their highly developed sensory systems.
