In 1667, a Danish scientist made a groundbreaking discovery. He concluded that certain mysterious stones, which were highly prized for their supposed medicinal powers, had not fallen from the sky during lunar eclipses, nor were they serpent tongues. In fact, they were fossilized teeth, many of which belonged to a prehistoric species that would come to be known as the megalodon, the largest shark to have ever lived.
What was it like when the megalodon ruled the seas? And what led to the extinction of this formidable predator? Because their skeletons were cartilaginous, what remains of megalodons are mostly scattered clues, like some isolated vertebrae and lots of their enamel-protected teeth. Like many sharks, megalodons could shed and replace thousands of teeth over the course of their lives. Interestingly, some fossil sites harbor especially high numbers of small megalodon teeth. Experts believe these were nurseries that supported countless generations of budding megalodons. They grew up in sheltered and food-packed shallow waters before becoming unrivaled adult marine hunters.
Looking at the similarities with great white shark teeth, scientists estimate that megalodons might have stretched up to 20 meters—three times longer than great whites. During their reign, which began around 20 million years ago, megalodons lived just about everywhere, with individuals also potentially undertaking transoceanic migrations. The world was warmer and the ocean was brimming with life. Otters and dugongs thrived in newly formed kelp forests, and baleen whales were at their most diverse. Megalodons had no shortage of high-energy, edible options. And it seems they were ambitious eaters. Analyzing megalodon teeth, scientists confirmed they were apex predators that not only ate large prey species but also other predators, perhaps even each other.
In addition to megalodon’s teeth, researchers have access to one exceptionally well-preserved spinal column that comprises 141 vertebrae of a 46-year-old megalodon. A 3D model of the megalodon’s body suggests that its stomach could reach volumes of almost 10,000 liters—big enough to fit an entire orca. Reconstructing their jaws, researchers think megalodons could eat a now-extinct 7-meter sperm whale in as few as four bites. And the fossilized bones of ancient cetaceans do indeed show evidence of megalodon bite marks—including some that healed over, confirming that megalodons pursued live prey.
But if megalodons were so powerful, why did they go extinct? It seems there were a few contributing factors. By the time they disappeared around 3.5 million years ago, the global climate had cooled, causing more glaciers to form and the sea level to drop. This dried up many coastal habitats, meaning some of the world’s most resource-rich marine sites were lost. About a third of all marine megafauna eventually went extinct, so fewer prey species were available. Megalodons already faced high energetic demands because of their size and the mechanism they likely used to regulate their body temperature, which allowed them to navigate cold waters and attack prey with bursts of speed. Environmental changes may have made megalodons vulnerable and increasingly put them in competition with other predators, including the great white shark, a relative newcomer.
Because megalodons were highly mobile predators, their extinction had global consequences. The end of their long-distance travels probably disrupted nutrient transport between different ecosystems. And many animals were suddenly released from the immense predatory pressure of their bite. Interestingly, some marine mammals dramatically increased in size afterward, which was perhaps partially afforded because they were no longer dealing with such a mega-existential threat.
Knowing that the decline of apex predators can destabilize entire ecosystems, conservationists are working to prevent today’s sharks from facing a similar fate—this time, because of humans. Meanwhile, the megalodon remains a colossal testament to ecological interdependence and millions of years of bones well-bitten and waters well-wandered.
Research the timeline of the megalodon’s existence. Create a visual timeline that includes key events such as its emergence, peak, and extinction. Use drawings, dates, and short descriptions to illustrate the timeline. This will help you understand the historical context and the changes in the environment that affected the megalodon.
Build a diorama that represents the habitat of the megalodon. Include elements like shallow waters, kelp forests, and other marine life that existed during the megalodon’s reign. Use materials like clay, cardboard, and paint to make your diorama realistic. This activity will help you visualize the environment in which the megalodon lived and hunted.
Imagine you are a young megalodon living in a nursery area. Write a diary entry describing your daily life, including what you eat, where you swim, and any challenges you face. This creative writing exercise will help you empathize with the megalodon and understand its behavior and lifestyle.
Create a model of a megalodon tooth using clay or another moldable material. Compare it to the teeth of modern sharks by researching their shapes and sizes. Discuss why the megalodon’s teeth were so effective for its diet and how they differ from those of other sharks. This hands-on activity will help you understand the physical attributes that made the megalodon a successful predator.
Split into groups and research different theories about why the megalodon went extinct. Each group will present their findings and argue why their theory is the most plausible. After the presentations, hold a class debate to discuss the various factors that could have contributed to the extinction. This activity will help you develop critical thinking skills and understand the complexity of extinction events.
discovery – the act or process of finding or uncovering something – Archaeologists made a remarkable discovery when they found ancient ruins buried beneath the desert sands.
stones – hard, solid, non-metallic mineral matter – She collected colorful stones from her travels and displayed them in a glass jar.
medicinal powers – the ability of something to have a healing or therapeutic effect – Traditional Chinese medicine believes that certain herbs possess powerful medicinal powers.
fossilized teeth – teeth that have been preserved and turned into rock over a long period of time – The museum had a remarkable display of fossilized teeth from extinct species.
megalodon – a giant, extinct species of shark – The megalodon was a fearsome predator that ruled the prehistoric oceans.
shark – a large, predatory fish with a cartilaginous skeleton and several rows of sharp teeth – We saw a shark swimming near the shore while we were on vacation.
skeletons – the internal framework of bones in a human or animal body – The paleontologists carefully excavated the dinosaur skeletons from the dig site.
vertebrae – the series of small bones that make up the backbone of a vertebrate – The doctor examined the patient’s X-ray and identified a fracture in one of the vertebrae.
teeth – hard, calcified structures in the mouth used for biting and chewing food – The dentist recommended brushing teeth twice a day to maintain good oral hygiene.
predator – an animal that hunts, kills, and feeds on other animals – The lion is a fierce predator that preys on zebras and wildebeests in the savannah.
