Extinct Sharks

Extinct Sharks

The first sharks appeared in the Devonian, about 420 million years ago. From the Cretaceous 100 million years ago, many species of sharks adopted their modern form. Since then, there have been around 500 species of sharks grouped into 35 families.

Sharks breathe through five to seven-gill slits. In general, the more primitive the family, the higher the number of slots.

Well-preserved shark fossils are very rare given the cartilaginous nature of the skeleton. Most often only the teeth resist weathering. In addition to these teeth, one can also find tiny dermal denticles covering their body and the spines that are sometimes found in front of their dorsal fin.

sharks history

Did you know that sharks appeared just over 400 million years ago?
… And that today we still coexist with a prehistoric shark?
Incredible true? But true!

As all the species of animals that live in the earth, and continue to inhabit the planet Earth, the shark has evolved over hundreds of millions of years until it reaches what we know it today. there are some Extinct Sharks species we will talk about it in this article :

Extinct Sharks Species

Although as we say, there is a species of a prehistoric shark that is still alive today in the depths of our oceans and that we will talk about a little later.

But the best way to tell a story so that it is perfectly understood is to start from the beginning, so from there we will start this long walk through the depths of the seas and oceans.

Get wet with us a little and let’s meet these Extinct Sharks!

Types of prehistoric sharks

First of all, it must be pointed out that everything that is known about prehistoric sharks is thanks to the fossilized teeth and vertebrae that have been found from some of them or by finding rocks with some fossilized impression of some dead shark body.

This is so because sharks do not have bones but cartilage, which break and disappear very easily.

So also many of the things that are known about them, regarding their behavior, dimensions, etc. they are still mere assumptions in most cases, based primarily on what is known of sharks today.

Having said all this, let us go without further delay to how the evolution of sharks has been and the different types of prehistoric sharks that have existed and that, as we have been saying, some of them continue to exist today.

1-Cladoselache

The Cladoselache was one of the first prehistoric sharks to inhabit the depths of the ocean, almost two meters long. It lived during the Devonian period, that is, from about 416 to 360 million years ago, and fossils of it have been found in both North America and Europe.

Some of the physical characteristics of this prehistoric shark would be:

• Mandible fused to head; this would prevent him from bringing his jaw forward in the attack of his prey, as sharks currently do, thus limiting the size of the animal to attack.
• The teeth were smooth, so it would swallow its prey whole.
• He had very strong jaw muscles.
• His mouth was large and was in the center of the head. This would make it easier to gobble up their prey, which they are supposed to “suck” from the tail of their prey towards the head.
• It had two dorsal fins and a crescent tail fin, similar to that of current sharks. This would make him a great and fast swimmer.

2-Orthacanthus

the Orthacanthus is a prehistoric shark almost 4 meters long and with two rows of teeth!

This shark that could remember the body of an eel lived during the Devonian-Triassic period, which would be from 400 to 260 million years old.

It has been found in the area of ​​North America and Europe

3-Falcatus

The Falcatus is a small shark of about 25 – 30 centimeters that lived in the Carboniferous, 350 to 320 million years ago, which has been found in the United States.

The main characteristic of this prehistoric shark is not precisely its size, but the physical difference that existed between males and females; and it is that the males had on the upper part of their dorsal fin a kind of thorn or ornament that was curved towards their head.

Its main food, something that surely you also like, prawns!

4-Xenacanthus

The xenacanthus was a prehistoric shark that lived between the Devonian and the Permian period, ie since about 310 to 202 million years ago.

Its main feature, which was one of the first freshwater sharks .

Other striking features of this prehistoric shark was that it had an elongated and fine body, similar to that of the eel.

It had a dorsal fin from its head to its tail, which was supposed to be covered with some kind of tissue that made it look as if they were vertebrae, which, according to some paleontologists, could have some type of poison that would serve as a defense.

4-Edestus

The edestus is a prehistoric shark that lived during the Late Carboniferous, from 300 ago – 250 million years.

It is one of the giant’s murderers of the sea, reaching about 6 meters long and weighing between 1 or 2 tons, more or less as is our current great white shark.

Its main feature, a mouth full of rows of teeth that kept coming out and never fell!

A denture that served to tear and bleed his prey and then devour it.

5-Helicoprion

The Helicoprion is a prehistoric shark about 3 meters long that lived during the Upper Carboniferous period, about 280 million years ago.

It is perhaps one of the strangest prehistoric sharks; and is that the teeth of its lower jaw are placed in a spiral as if it were a circular saw. Which would serve to tear and bleed his prey, to eat it easily?

Unlike the Edestus shark, the Helicoprion shark would lose its teeth as new teeth emerge.

5-Hybodus

Closer to the time of the dinosaurs, we find the prehistoric shark Hybodus. A shark about 2 meters long that appeared in the late Permian period to go extinct in the Upper Cretaceous, about 180 million years ago.

Its main and striking feature is that it had two types of teeth as if one used to chew and others to bite.

This suggests that they were opportunistic sharks rather than natural hunters.

6-Paleocarcharias

It is the prehistoric shark from which the current bull shark and hammerhead shark come, which lived around 150 million years ago in Europe.

Physically it is very similar to the current sharks since it already has a caudal fin, gill openings on the sides, thick and rough skin.

7-Ischyrhiza

The Ischyrhiza, is a prehistoric shark about two meters long , which lived during the Cretaceous, about 144 – 65 million years ago.

Its main characteristic, a long and fine snout that would allow it to feed on worms and other types of crustaceans.

This is the ancestor of the current sawtooth shark .

8-Squalicorax

The Squalicorax or raven shark, lived in the Late Cretaceous Period, 105-65 million years ago.

This shark could be up to five meters long and fed on everything that was in the water, including the odd clueless dinosaur, and that its numerous teeth were not too large, as they were no larger than 3 Centimeters, yes, they were curved and sawn, like those that the tiger shark may have today.

9-Cretoxyrhina

The cretoxyrhina lived in the late Cretaceous period, which is from 100 ago to 82 million years.

In terms of physique, it already closely resembles current sharks, measuring up to 7 meters.

A born predator with smooth, curved 7-centimeter teeth that would have nothing to envy the much-feared white shark today, with similar similarities.

10-Ptychodus

The cretoxyrhina lived in the late Cretaceous period, which is from 100 ago to 82 million years.

In terms of physique, it already closely resembles current sharks, measuring up to 7 meters.

A born predator with smooth, curved 7-centimeter teeth that would have nothing to envy the much-feared white shark today, with similar similarities.

11- Otodus

This shark lived in the Paleocene-Eocene period, that is, from about 60 to 45 million years ago.

He was also one of the giants of the ocean, reaching about 9 meters and weighing about 2 tons, having enormous and sharp triangle-shaped fangs that could measure up to almost 13 centimeters!

Come on, there was no marine animal that could not sink its teeth into!

12-Megalodon

But for giants the Megalodon. It is the best known prehistoric giant shark. It could measure up to 20 meters and weigh about 100 tons. It is the white shark in a super-augmented version.

The scientific name is Carcharodon Megalodon, which means “big tooth”. This giant shark lived during the Cenozoic, between 19.8 and 2.6 million years ago.

It is clear that the Carcharodon Megalodon had no problem when hunting, and could even catch sperm whales, and is that you get the idea, his teeth could measure up to 18 centimeters!

Teeth that were sawn, robust in structure and triangular in shape.

Altogether about 276 teeth distributed in several rows from which it was impossible for a prey to escape.

Evolution of prehistoric sharks

As you have seen many of these sharks have shared time and space, it is not that there has been, or at least is not known at the moment, a clear sequence or evolution between all of them that leads from one species to another until finally reaching the sharks current.

Then, the question to ask would be : why have some been living more than others?

Simple, each of the species has to  evolve and adapt to the needs of the moment or simply disappear. Evolution and higher functions that are transmitted to successive generations that make the species last and have the ability to compete for food, for example.

A clear example of this evolution could be the fact that sharks have been strengthening their skin and, above all, being able to push their jaws forward allowing a greater opening with a much greater final closure.

Why Giant Sharks Went Extinct?

The last specimen of a giant shark, whose scientific name is Carcharocles Megalodon, became extinct more than 2.5 million years ago. Until now, nobody knew the exact causes of the disappearance of this species, but a group of Italian scientists has discovered the reason that led to their death: it seems that the diet these sharks had influenced their unfortunate future much more than until now it was thought.

It has been a team of researchers from the University of Pisa, in Italy, who have discovered the causes that led to the extinction of the giant shark -which reached up to 16 meters-, which was once one of the most predatory dangerous that have lived in the oceans. Its disappearance led to the transformation of the species and led to the emergence of specimens that we know today and that are less harmful than their ancestors.

Richard Gray, a researcher, has revealed that: “The disappearance of the last giant shark could have been caused by the decline and fall of several mid-sized baleen whale dynasties in favor of the modern, giant whale we know today. “

The giant sharks began to see their food rations depleted when medium-sized whales began to disappear for various reasons related to climate change. This left the predators without their main food source and gradually began to disappear until they became extinct.

That climate change caused the whales to get more food and little by little the giants emerged, as we know them. The Sharks no longer had such easy prey and could not adapt to the times running, so eventually disappear gradually.

are sharks endangered?

The organization International Union for Conservation of Nature (IUCN) has included in its Red List 17 species of sharks in “danger of extinction”, after an evaluation of 58 species of sharks and rays.

The ‘grandfather’ of the white shark and the megalodon was rather small

An international team of paleontologists has discovered an ancestor of the great white shark. As reported in Scientific Reports , the Lamniforms and the shark Palaeocarcharias stromeri , which lived 145-152 million years ago, have the same dental structure characteristic of this order.

The order of the Lamniformes includes large oceanic whitetip sharks that live in tropical and temperate waters that feed on bony fish and mammals. The team includes seven modern families and several extinct ones. This includes the white shark ( Carcharodon carcharias ) and the largest known shark, the megalodon ( Otodus megalodon ) , which died out about 2.6 million years ago.

The oldest member of the order is the shark Heterodontus polonicus , which lived in the early Cretaceous period (133-140 million years ago). However, the origin of the lamini is still unclear. Its possible ancestor, the shark Palaeocarcharias stromeri , which lived at the end of the Jurassic period (145-152 million years ago), belonged to the Lamino.

this article translate from : https://dinosaurioss.com/tiburones-prehistoricos/