Prehistoric shark scales offer a peek into the populations of reef predators prior to human interference

Paleontologists garnered attention by employing ancient shark scales to assemble shark populations from epochs long past. Simultaneously, a multinational group of scientists under the leadership of ecologist Erin Dillon from UC Santa Barbara utilized this technique for recent historical periods.

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2025 September 14 . 11:10 PM

2 min read

Prehistoric shark scale findings offer insights into ancient reef predator demographics prior to... — Prehistoric shark scale findings offer insights into ancient reef predator demographics prior to human interference

Prehistoric shark scales offer a peek into the populations of reef predators prior to human interference

In a groundbreaking development, an international team led by UC Santa Barbara ecologist Erin Dillon has applied a novel method to reconstruct past shark populations and diversity, with a focus on shark management and conservation.

The study, which was the first of its kind, reveals that shark populations have experienced a significant decline worldwide since records began in the mid-20th century. This decline is particularly pronounced in Caribbean Panama, where the biggest drop occurred in the latter half of the 20th century.

The team, which includes researchers from several institutions, collected dermal denticles from a site in Borneo approximately 7,000 years old. These shark scales, composed of dentin with a hard enamel surface, are often used by scientists to reconstruct ancient ecosystems.

The analysis of these fossil shark scales revealed a 71% decrease in total shark abundance between the mid-Holocene and the present. The results indicate that shark abundance in Panama declined roughly three-fold since prehistoric times.

Interestingly, the decline was more pronounced among swifter-swimming species such as requiem and hammerhead sharks, while demersal species like the nurse shark experienced less of a decline.

Dillon and her team collected sediments from a fossil reef in Bocas del Toro, Panama, over several years. The team used radiometric dating to estimate the age of the reef at around 7,000 years ago. The study of these sediments provided insights into the types of sharks that inhabited the ancient reef and their relative numbers.

Dillon plans to study variation in the rates at which different shark species shed their scales. She also encourages other researchers to apply this powerful technique to other locations around the world. The hope is that this research will contribute to the conservation and management of shark populations, ensuring their survival for future generations.