Sharks

The Paleozoic era 545-250 million years ago

545 BCE

It is thought that sharks originated from small leaf shaped fish with no eyes.These fish then evolved into the two main groups of fish we have today, bony fish and cartilaginous fish. The first recognisable sharks with the genus Antarctilamna showed up around 380 million years ago. In this period a rapid number of shark species increased. In an age called the carboniferous many sharks evolved strangely, none of the sharks from this time period are still alive today.

Early Jurassic Period 195 million years ago

195 BCE

By this time the oldest known group of modern sharks had begun to evolve, these sharks were six gill sharks also known as Hexanchiformes. Most other modern shark groups also began to evolve at this time. It was at this point that sharks began to grow flexible protruding jaws allowing them to eat bigger prey, while also evolving to swim faster.

The Cretaceous Period 145-66 million years ago

145 BCE

At the beginning of the period sharks were widely common before experiencing a mass extinction event. While much life did become extinction such as dinosaurs sharks continued on. However, they were still effected by the event many of the largest shark species died in the event. Only the smallest and deep sea sharks that mostly fed on fish survived. The picture shows the tooth of a megalodon the largest shark species to ever live compared to the tooth of a great white shark.

Great White Sharks 66-23 million years ago

66 BCE

Many scientists used to believe that the great white shark and the megalodon were closely related. However recent fossil records have proved that statement to be false. Scientists found that great white sharks are actually more closely related to the ancestors of mako sharks. Scientists now believe that it is more likely the great white sharks ancestors were competing with the megalodon for food.

Hammerhead sharks 23 million years ago

23 BCE

Hammerhead sharks are believed to be the youngest shark species. Fossil records suggest they have been around for 45 million years however molecular data points to them having been around for 23 million years. The strange shape on the head of the hammerhead is to help with electroreception, improves their vision, and enhance their swimming.

How Science Changes Over Time

2022

It's important to know the history of sharks and other animals to help us get a better picture of the evolution of species across the globe. Finding the ancestry of sharks and other animals helps us with finding and determining the role of mutations and what causes them. It also helps prove and disprove theories made by biologists in the past to determine if those theories are correct or not. This also relates to ecosystems as sharks are a keystone species and are essential to the marine life.