Lecture Notes: Megalodon - The Apex Predator of the Prehistoric Oceans

Introduction

• Megalodon: Means "big tooth".
• Prehistoric shark with massive jaws, deadly serrated teeth.
• Dominated even the biggest whales in the ocean.
• Teeth were huge: 6-7 inches long, serrated, shaped like broad triangles.
• Mysteriously disappeared from the fossil record about 2 million years ago.
• Scientists investigating shape, size, and behavior.

The Ancient Oceans

• Water covers almost 70% of Earth's surface.
• Life began in the oceans.
• Early underwater predators included giant predatory fish, squid, stingrays, toothed whales, etc.

Shark Evolution

• Sharks have existed for over 400 million years.
• Biology of these sharks has remained stable.
• Prehistoric sharks now extinct, but great white sharks have survived for over 10 million years.

Megalodon's Dominance

• Megalodon lived from roughly 25 million years ago to about 2 million years ago.
• Largest predatory shark known in the fossil record.
• Was an apex predator with massive razor-sharp teeth and the size of a Greyhound bus.
• Scientists gather information from fossilized teeth and a few pieces of backbone.

Anatomy and Adaptation

• Cartilage Skeleton: Sharks' skeletons are made of cartilage, which decomposes quickly, leaving mainly teeth in fossils.
• Scientists use teeth to reverse-engineer the structure of Megalodon.

Fossil Discoveries

• Important sites for Megalodon fossils include Calvert Cliffs, Maryland.
• Teeth provide crucial information about the shark's biology and habits.
• Megalodon's teeth had compression fractures from biting down on hard surfaces like bone.
• Sharks have adapted over millions of years by continually replacing lost teeth.

Comparing to Great White Sharks

• Great white sharks often used as a model to understand Megalodon.
• Great whites reach 6 meters in length; Megalodon estimated at 15-17 meters and up to 45,000 kg.
• Bite Force: Megalodon had an estimated bite force of 40,000 pounds, far exceeding the great white's bite force.

Megalodon's Prey and Hunting Strategies

• Likely prey included smaller whales, sea cows (dugongs), and large whales.
• Used powerful jaws and serrated teeth in a thrusting, sawing motion.

Modern Scientific Techniques

• Digital Modeling: Used to estimate size and shape of Megalodon based on teeth and rare vertebrae.
• Realistic reconstructions displayed in museums like the San Diego Natural History Museum.

Speculations on Extinction

• Megalodon disappeared around 1.8 million years ago, possibly due to cooling ocean temperatures and changing prey availability.
• Adaptability: Unlike Megalodon, the great white shark has shown greater adaptability and dietary variety.

Comparative Anatomy and Evolutionary Debate

• Debate on whether Megalodon is directly related to the great white shark or not.
• Fossil vertebrae and tooth shape analysis suggest different evolutionary lines.

Conclusion

• Despite its extinction, Megalodon remains a unique example in the 400 million-year history of sharks, primarily due to its massive size and powerful predatory capabilities.