During this time the sea was filled with a variety of bony fish

One of these fish was the Acanthodian which was the first ancestor of todays shark.

This time is when the very first fully developed shark ,the leonodus shark evolved.

However it's fossil of it's two pronged teeth leads scientists to beleive it was 16 inches long with an eel like body and it lived underwater.

After about 50 million years after the Silurian era the Devonian era began

It was 6 feet long, with a streamlined body,had 5-7 gill slits, and dorsal fins.

The cladoselache was different from it's eel like ancestors, because it's body looks more as one of a modern shark.

The main difference between this shark and modern sharks are the round nose shape, lack of claspers, and it's jaw was inflexible and fixed to it's head

During the late Devonian era the first modern shark appeared, the cladoselache

450 million years ago during the Silurian Era harks had started as a unique species

Acanthodians also called spiny harks were the first fish to develop the characteristics of a shark, and to develop the skeletal structures that define shark.

Sharks also split into many subspecies including rays, skates, and chimearas.

Some of the most unique sharks ever were in this era. A few examples are the Stethacantus, a shark like a flat anvil like, spiky fin, the Eugeneodontida, a shark with a tooth whorl at the end of their bottom jaw, and the Falcutus, nickname unicorn shark, grew a long sharp horn on it's head, evolved during this period

Sharks had incredibly diverse phsiognomy during the carboniferous era.

The carboniferous era began around 360 million years ago. It was this time that sharks dominated the sea.

Thesse species of sharks are the predecessors of all sharks that live today

During this period sharks began to evolve flexible and protrudging jaws so they could attack and eat larger animals. They also developed tail fins that helped them swim more efficiently and faster. Most sharks also began to develop mouths underneath their snout.

The jurrasic era started around 200 million years ago, and during this era 12 new species of sharks appeared.

One of the more revolutionary quirks of this period was the appearance non-extinct horned sharks like the hybodus.

Filter feeders like the whale shark, the basking shark, and the megamouth first appeared.

During the cretaceous period 145 to 65 million years many of the sharks which are still alive today developed. Deep sea sharks such as the Goblin shark or the frilled shark originated from this era.

Lamnidae are the predecessors of modern sharks like the great white's,,Mako sharks, and bull sharks.

The Cretaceous period was also the time when lamnidae sharks, also refereed to as white sharks, with the atonomy of what we think of sharks having today, evolved.

Megalodon's were the biggest ocean predators to ever exist reaching 65 feet in length and weighing over 30 tons.This predator had 7 inch long teeth and would eat whales!

Megaladons weren't the only humongous shark found in the Cenozoic era, another shark called the Otodus grew to a length of 39 feet which is twice the length of the biggest great white sharks.

During the Cenozoic era , about 60 million years ago one of the most famous prehistoric shark evolved , one that showed sharks as a efficient apex predators:the Megalodon.

Another freshwater shark that lived in this era was the Antarctilamna which was also eel like but had a small fin behind it's head.

Currently there are around 440 different shark species swimming in the oceans however scientists continue to find unique species each year and we never know what unique evolutionary traits we will discover next.

Most of the sharks today have evoloved from the modern Cenozoic, except for the truly ancient sharks from the cretaceos period.

I will do this by comparing a prehistoric and modern at one time

Hammerheads are usually found at the bottom of the sea stalking their prey.

They also eat other sharks and stingrays, (which are a favorite).

An hammerheads average lifespan is from around 20-30 years.

Inquiry question: How have sharks evolved over the years and how are modern sharks different and similar to prehistoric sharks.

Hammerheads teeth have smooth edges with a distinct notch on the distal side of the tooth.

Hammerheads teeth can be from about 1/4 to 3/4 inches in length

Hammerhead sharks have from 5-15 rows of teeth on each jaw.

They mainly eat small fish but also eat crustaceans and squid too.

Sand sharks are inactive during the day but is active during the night

Goblin sharks eat fish both big and small including sharks and rays

The Goblin sharks have long sharp teeth in the front of it's mouth.

Their teeth are long,very sharp, and narrow with smooth edges.

Their upper jaw has about 44-48 teeth.The bottom jaw has around 41-46 teeth,.

Their teeth are long, slender and fang like which are connected to their soft delicate jaws. Some people even call the goblin shark snaggle toothed

Goblin sharks have 26 large teeth on the upper jaw and 24 large teeth on the lower jaw. the jaws have 3 rows of teeth.

Angel sharks eat crustaceans, fish and mollusks.Thaey spend their lives hidden in sand and rocks waiting for a fish to arrive so they can pounce on them.

The main and only food that the basking shark eats is plankton

The angel shark has 9 rows of teeth on the upper jaw and 10 rows of teeth on the lower jaw.

Females are from 15-21 feet long and males are from 11-13 feet long.

In conclusion sharks were one of the first animals to roam the earth. Sharks have changed in many different ways and prehistoric sharks were way more powerful than sharks today. I hope that you've enjoyed my my presentation and have a nice day.