For what reason did Megalodon go wiped out?

In 1667, a Danish scientist made a groundbreaking discovery: the peculiar stones revered for their supposed mystical powers, once believed to have fallen from the sky during lunar eclipses and mistaken for snake tongues, were, in fact, fossilized teeth. Many of these teeth belonged to an ancient creature species that would later be known as megalodon, the largest shark to ever exist. But what was it like when megalodon ruled the seas? And what led to the demise of this colossal predator?

Due to their cartilaginous skeletons, only scattered remains of megalodons have survived, such as isolated vertebrae and abundant deposits of their formidable teeth. Like other sharks, megalodons continuously shed and replace thousands of teeth throughout their lives. Interestingly, certain fossil sites contain vast quantities of small megalodon teeth, suggesting they were nurseries that supported generations of growing megalodons. These young sharks thrived in shallow, food-rich waters before maturing into formidable adult marine hunters.

Comparing their teeth to those of great white sharks, scientists estimate that megalodons could reach lengths of up to 20 meters—significantly larger than great whites. During their reign, which began approximately 20 million years ago, megalodons roamed the oceans freely, possibly undertaking long-distance migrations. The world was warmer, and the seas teemed with life. Otters and dugongs flourished in newly formed kelp forests, while baleen whales were abundant. Megalodons had a plethora of high-energy, appealing prey options.

Studies analyzing nitrogen isotopes in megalodon teeth confirm that they were apex predators, consuming not only large prey species but also other predators, possibly even each other. Researchers have also uncovered a remarkably preserved spinal segment containing 141 vertebrae from a 46-year-old megalodon. Based on a 3D model of the megalodon's body, it's estimated that its stomach could hold volumes of nearly 10,000 liters—large enough to accommodate an entire orca. By simulating their jaws, scientists believe megalodons could consume a now-extinct 7-meter sperm whale in as few as four bites. Fossilized bones of ancient cetaceans indeed bear evidence of megalodon attacks, including healed-over bite marks, confirming that megalodons preyed on live animals.

But if megalodons were such formidable hunters, why did they become extinct? Several factors likely contributed to their demise. Around 3.5 million years ago, as the global climate cooled, glaciers formed, and sea levels dropped, causing the loss of many coastal habitats. This resulted in the disappearance of numerous prey species, leaving megalodons with fewer food options. Additionally, their large size and the mechanism they likely used to regulate their internal temperature, allowing them to explore cold waters and ambush prey with bursts of speed, may have made them susceptible to environmental changes and increased competition from other predators, including the newly emerged great white shark.

As megalodons were key players in their ecosystems, their extinction had far-reaching consequences. The disruption of their extensive migrations likely affected nutrient transport between different habitats, and many animals were suddenly released from the intense predatory pressure of their attacks. Interestingly, some marine mammals notably increased in size afterward, possibly surviving because they were no longer threatened by such a formidable predator.

Understanding the ecological repercussions of the decline of apex predators, conservationists are working to prevent modern sharks from facing a similar fate—this time, at the hands of humans. Meanwhile, the megalodon remains a testament to biological interdependence and a reminder of an era of bones gnashed and waters roamed.

Understanding how enormous megalodon grew is intriguing. Despite the scarcity of their body fossils, we can estimate the size of this fish by measuring the remains we do have and comparing them to existing sharks. A simple method for determining length is to measure the tooth row length from the front to the side of the jaw. By multiplying this measurement by eight, we can estimate the precaudal length of our shark, which should span from the tip of the shark's nose to where the tail begins. Since megalodon likely had a tail similar to that of a great white shark, we then add 25 for the tail. Scientists estimate that megalodon could have reached lengths between 15 and 18 meters, roughly double the size of a bus or multiple times the size of a great white shark.