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450 BCE
The first shark
(450 million years ago)
The most ancient organism of the shark is part of the acanthodians, “spiny sharks”; created from the diversification of bony and jawed fish.
It resembles small modern sharks but has varying fins.
Some of its features were:
- Strong spines grew from the base of the head to the pectoral fins.
- Tiny diamond-shaped scales
- cartilaginous bone structure
- Teeth grow inside the mouth and move forward.
- the mouth opens at the front of its skull
- Forked tail -
380 BCE
The first recognisable sharks
By the Devonian period, the species Antarctilamna had appeared, which looked more like eels than sharks. It is about this time that Cladoselache also evolved. This is the first group that scientist recognises as sharks today, but it may have been part of the chimaera branch meaning it is not technically a shark. They were active predators and had torpedo-shaped bodies, forked tails and dorsal fins. -
360 BCE
Carboniferous Age
The Carboniferous Period is known as the golden age of sharks. An extinction event killed off about 75% of all species which allowed sharks to dominate, and evolve into a whole variety of shapes and forms. Some of the strangest prehistoric 'sharks' evolved in this time. These include Stethacanthus: which had an anvil-shaped fin on its back. Helicoprion: with a spiral buzz saw-like bottom jaw, and Falcatus: which had a long spine jutting out of the back and over the top of the head. -
252 BCE
Oldest modern shark
By the Early Jurassic Period the oldest species of modern sharks, the sixgill sharks, had evolved. They were followed during the rest of the Jurassic period by most modern shark groups. It was at this point that they evolved flexible, protruding jaws, allowing the animals to eat prey bigger than themselves, while also evolving the ability to swim faster. This is where the characteristic of strong jaws developed in sharks. -
140 BCE
Shrinking sharks
At the beginning Cretaceous Period, sharks were widely common and varied in the sea, before going through the fifth mass extinction event. While much of life became extinct during the extinction event, including all non-avian dinosaurs, sharks once again persisted. However, they were still impacted and fossil teeth show that the asteroid strike killed off many of the largest species of shark. Only smaller and deep-water species that fed primarily on fish survived. -
65 BCE
Lamnoids (Great white)
The lamnoids include some of the best-known sharks, such as the great white and sand tiger. The great white and megalodon coexisted for about 10 million years. These predators kept out of each other’s way by feeding on different prey (megalodon on whales, the great white on seals) and living in different areas, megalodon in warm water and the great white in cooler water. They are characterised by heavily-built, solid teeth and a torpedo-shaped body. -
23 BCE
Hammer head shark
The hammerhead shark appeared during the Neogene period. (23 million years ago) The strange shape of their head is an adaptation to help electroreception which is the detection of naturally occurring electric fields as they hunt for prey. It also improves their vision and enhances their swimming sense of smell. -
16 BCE
Megaladon shark
From 16 million to 2.6 million years ago, megalodons ruled the oceans. These sharks had physical and behavioural similarities to today’s great whites. While their exact size is still unconfirmed, megalodons were about 12 to 21 metres long. These massive sharks fed on whales and other marine mammals. Scientists theories that sharks swam in warm waters and a lowering of ocean temperatures may have led to their extinction. -
Most modern shark
The newest organism of the shark is the sixgill sawshark. It was discovered off the coast Madagascar in 2020.
Features:
- 6 pairs of gill slits
- barbs on the rostrum continue to the sensory barbels
- Average length is 170cm
- Has 2 dorsal fins, 2 pectoral fins, 2 pelvic fins
- Long snout edged with sharp teeth
- Pale brown colouration
- Large, beady eyes
