14 DAY TRIAL // From the Oligocene to the Pleistocene epoch, megalodon was the largest shark to have ever lived. It roamed Earth's waters between 25 and 1.5 million years ago, and researchers say that it is the ancestor of modern-day sharks. These creatures could grow to impressive sizes, with some specimens believed to have been about 16 meters (52 feet) in length. These data were extracted from studies of fossilized teeth, some of which were found to be as much as 16.8 centimeters (6.6 inches) long. In a recent series of studies conducted in the Isthmus of Panama, researchers discovered a nursery location, where individuals of the now-extinct megalodon species took care of their young, LiveScience reports.
In the past, the Pacific Ocean was connected to the Caribbean Sea through a stretch of salty, shallow seawater. According to geologists, this area had a depth of no more than 25 meters (82 feet), which provided the megalodon with the ideal conditions it needed for rearing its young. It's interesting to note here that the fetuses researchers found were up to 4 meters (13 feet) in length. The Isthmus of Panama has thus far revealed two fossil sites, where teeth of specimens as much as 10 million years old were found. The troves contained up to 400 teeth each, and analyses of these fossils contributed significantly to researchers gathering a large portion of the knowledge they have of the creature today.
One of the things that surprised researchers was the fact that most of the teeth discovered at the two locations appeared to be a lot smaller than they expected. As opposed to the teeth found in adult specimens, these ones most averaged a length of 1.6 to 7.2 centimeters, which led researchers to propose that they in fact belonged to juveniles. Other proposals said that the fossils might come from a dwarf species of megalodon, or that they were adult teeth from the back rows, not those in front that were generally longer.
“It is amazing how we were able to reconstruct a behavioral strategy used by ancient sharks based on fossils,” explains Smithsonian Tropical Research Institute expert Catalina Pimiento, who is also a research biologist at the University of Florida. Megalodons, “even in their largest forms, have used nursery areas for millions of years as an adaptive strategy for their survival,” the specialist adds. The shallow area that the sharks used offered a rich source of food, as well as a more efficient defense line against predators that may have attempted to eat the young megalodons. Details of the investigation appear in the May 10 issue of the open-access scientific journal PLoS ONE.