Earth's Six Great Sharks: The Birth of Modern Marine Killing Machines
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Sharks, the most ferocious predators in the world's oceans today, have existed for more than 50 million years and have survived multiple mass extinctions.Currently, there are nearly 500 species of sharks discovered by humans, which can be called one of the most successful species in the earth's evolution, right?Sharks belong to the cartilaginous fish.
It first appeared in the Paleozoic Era, the Devonian period.For a long time, sharks and other primitive fish were not much different, with a body shape that was relatively weak.
1. Cladoselache (Cladoselache):
Until 3.6 million years ago, Cladoselache appeared.According to the fossil specimens unearthed, its body length is 1.8-2 meters, with two dorsal fins before the back, and its body shape is streamlined. Unlike the cross-fissure-like mouth of modern sharks,Cladoselache's mouth is a straight fissure, so it is named 'Cladoselache'.
Cladoselache belongs to the middle carnivorous fish at that time,Its streamlined body gave it a decent speed. But unfortunately, it lived in the age of the Deeanthus fish,The Deeanthus fish was called the 'King of the Devonian period',It was 10 meters long and 4 tons, like the strongest biting force produced by the upper and lower jaws, preying on Cladoselache. You can often see the picture of Deeanthus preying on Cladoselache and dying tragically.
2. Stethacanthus (Stethacanthus):
Also known as 'toothed fin shark',It first appeared in the early Permian period,30 million years ago, its body length is between 0.7-2 cm, living in near-shore areas (at the entrance to the sea).This shark is very easy to identify, it has a 'large plate' shaped dorsal fin on its back.
Later, based on fossil inferences, this dorsal fin structure, which was specially adapted, was only found in males, so it may be a device for displaying courtship.However, Stethacanthus was also in a 'bad time', the ocean was ruled by Deeanthus, and the shallow water was also the territory of Gongtu fish (including lungfish and Hissingrootfish).
The BBC documentary 'Walking with Beasts'has the most famous poster, which isHissingrootfishwith a Stethacanthus in its mouth. Stethacanthus: I'm so unlucky……3. Helicoprion (Helicoprion):An easy-to-remember shark with a strange appearance.
They lived in the ancient ocean of the Greater Geeta, from about 300 million years ago to the late Triassic period.
They have teeth arranged in arc or spiral shapes, feeding on corals and crustaceans,They were the rulers of the ocean at that time.But its spiral-shaped saw-like teeth are still debated about where they are located.Helicoprion'sbody length is about 10 meters,Fortunately, it survived the Permian-Triassic extinction, so it became the 'ocean overlord' in the early Triassic period. However, this 'ocean overlord' position has not been determined, but it,was quickly extinct after the emergence of fish and large marine reptiles.
4. Hybodus (Hybodus):Also known as 'bow shark',It lived from the late Permian period to the Jurassic period.Hybodus is the most documented ancient shark in the fossil records, with discoveries across major continents. According to fossil research, Hybodus has extremely sharp teeth, two dorsal fins, and sharp spines on each, although,
it swims slowly, but it is an opportunistic predator.
Hybodus's survival spanned the entire Mesozoic era, and scientists estimated that Hybodus ate a wide range of foods and often hunted young fish and reptiles, but,because it swam slowly, it was hunted by the Late Triassic dragonflies.5. Cretoxyrhina mantelli (Cretoxyrhina mantelli):Also known as 'White-ribbed shark',It is considered the 'throat of the White Cretaceous period', appearing in the early White Cretaceous period about 100 million years ago,
The average body length is 5.5 meters, and the maximum length is more than 7.6 meters, and the weight is about 3.5 tons. According to fossil reconstruction,today's Grey Murre is similar to it, belonging to the top predators. It is estimated that it consumes five tenths of its own weight per day, that is, 1.4 tons of food.
Another observation is that its teeth, longer than 6 cm, are suitable for hunting large prey, including young dragons and thin-plate dragons.
And by 8600-8200 million years ago, the appearance of the dragon and the giant dragon appeared, the White-ribbed shark transformed into a 'hunter' and then went extinct.6. Carcharodon megalodon (Carcharodon megalodon):The appearance of the giant shark belongs to the peak of the shark family history, appearing in the early New Stone Age to the late New Stone Age (120 million to 2 million years ago).Its body length is about 19 meters, and its weight is about 70 tons. According to fossil research, the giant shark consumes food that is five tenths of its own weight per day, that is, 1.4 tons of food.
A comprehensive observation is that its teeth, longer than 6 cm, are suitable for hunting large prey, including young dragons and thin-plate dragons.
Looking back at the evolution of sharks, it is a history of shark warfare. In the four mass extinctions (or possibly five), the shark family has always found a way to survive, from bottomless invertebrates to modern killing machines, it can be called one of the most successful species on earth. And they made it known to the world what 'iron shark, water dragon' means!
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