Sharks have been one of the most intriguing creatures of the ocean since time immemorial. These ancient fish have survived several mass extinctions and have evolved into over 400 species that exist today. This article takes you through a timeline of shark evolution to understand how these magnificent creatures evolved into the top predators of the ocean.
A Timeline of Shark Evolution
Ordovician Period (485 – 443 million years ago)
The earliest known sharks appeared in the Late Ordovician period, around 420 million years ago. These early sharks were small, jawless fish that were only a few centimeters in length and were named Cladoselache. These primitive sharks were filter-feeders and had no teeth, instead, had an armor-like skin that protected them from predators.
Silurian Period (443 – 416 million years ago)
During the Silurian period, a new species of shark evolved that had teeth for the first time. These teeth were not like the modern sharks’ teeth, instead, they were small and pointed and used for catching small prey. These early sharks were still jawless and are believed to be the ancestors of modern lampreys and hagfish.
Devonian Period (416 – 359 million years ago)
During the Devonian period, the first jawed sharks appeared, and they were the first predators of their kind. These early jawed sharks were larger in size compared to the previous jawless sharks and were the top predators in the ocean. This period saw the evolution of several shark species, such as Stethacanthus, which had a large, armor-plated back and were herbivore, and Cladoselache, which had sharp teeth and was a carnivore.
Carboniferous Period (359 – 299 million years ago)
The Carboniferous period saw the evolution of several new shark species, including the iconic megalodon, which was the largest shark that ever lived and measured up to 60 feet in length. Other shark species that evolved during this period include Hybodontiformes, which had serrated teeth and were probably the ancestors of modern-day sharks, and the Edestus, which had scissor-like teeth and were slow-moving filter-feeders.
Mesozoic Era (252 – 66 million years ago)
The Mesozoic era saw the evolution of several new shark species, including the Carcharodon megalodon, which was the largest predator of its time and measured up to 50 feet in length. Other shark species that evolved during this era include the Squalicorax, which had serrated teeth and was a fast and efficient hunter, and the Ischyrhiza, which had a large head and long, blade-like teeth that it used to catch large prey.
Cenozoic Era (66 million years ago – present)
The Cenozoic era saw the evolution of several new shark species, including the modern-day great white shark, tiger shark, and bull shark. These species have evolved to become the top predators in the ocean and have adapted themselves to efficiently satisfy their hunger with their predatory methods. During this era, several species of shark have become extinct due to changes in the ocean’s environment, overfishing, and human activities.
The Final Word
Sharks have survived several mass extinctions and environmental changes. Despite their fearsome reputation, they are essential to keep the balance of marine ecosystems. The timeline of shark evolution has been a fascinating journey through time and gives us a glimpse into their evolution and survival strategies.
