Emily Chan
In 1996, archaeologists hurriedly conducted excavations at a 13th-century coastal fishing site on Santa Catarina Island in southern Brazil before construction for a condo development began.
They collected a variety of artifacts, including tools, pottery, and animal remains, which are now housed in the museum at the Federal University of Santa Catarina. Today, the historical site is located beneath a beachfront property that sees a lot of activity.
Around 750 to 500 years ago, Indigenous peoples used that very same area for fishing. They often caught sharks and would butcher the fish before hauling them away.
The hunters usually left the shark heads behind, allowing modern-day experts a glimpse of what the marine ecosystem was like in the past.
The museum contains teeth from at least eight different shark species, providing a treasure trove of information.
A team of researchers compared the excavated teeth to modern shark teeth from the same region. They used a method called stable isotope analysis to determine the differences between the sharks’ diets and environment.
Shark teeth have collagen, a protein that includes elements like nitrogen and carbon, which are obtained from food. Higher nitrogen isotope values point to a diet of carnivorous or herbivorous prey rather than plants.
The researchers found that different types of sharks were feeding on many types of creatures that were on the same level of the food web.
That means if one kind of fish were to disappear, the sharks would still have plenty of others to choose from. It was a sign of a resilient ecosystem.
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