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Panama Canal Sharks

February 11, 2013

Panama Canal Sharks

Dynamiting a wider path from the Pacific to the Caribbean, the $5.6 billion Panama Canal expansion continues to expose a treasure trove of fossils

Dynamiting a wider path from the Pacific to the Caribbean, the $5.6 billion Panama Canal expansion continues to expose a treasure trove of fossils. Smithsonian scientists taking advantage of the canal widening project unearthed the remains of 12 different ancient shark relatives, supporting the controversial new claim that the connection between North and South America formed long before the accepted date of 3 million years ago.

When Catalina Pimiento arrived at the Smithsonian Tropical Research Institute in Panama as an intern she wanted to study live whale sharks. Soon she changed her mind, deciding to dig for shark fossils in the 20-million-year-old Culebra Formation and to enter a graduate program at the University of Florida, Gainesville. “The Canal expansion is really a once-in-a-lifetime opportunity to understand shark evolution and the history of the Panama land bridge,” said Pimiento. “Our most surprising finding was that the majority of these chondrichthyans [shark relatives] lived in fresh water, which means that there must have been land nearby even 20 million years ago.”

Like the bridge of your nose, shark skeletons are made of cartilage, not bone. Teeth and vertebrae provide the only clues to paleontologists looking for evidence of extinct sharks. By comparing the shark remains from the canal excavations to collections of extinct sharks from other locations, Pimiento and colleagues identified 12 species from six different families. “The range of sharks we found, from Carcharodon chubetensis -a primitive deep water ancestor of Megalodon measuring 12 meters to shallow water stingrays like Urobatis halleri, measuring only 20 centimeters tells us there were a variety of marine environments in the region.”

Reference: Pimiento C., Gonzalez G., Hendy A., Jaramillo C., MacFadden B.J., Montes C., Suarez S.C., Shippritt M. (2013) Early Miocene chondrichthyans from the Culebra Formation, Panama: A window into marine vertebrate faunas before closure of the Central American Seaway. Journal of South American Earth Sciences 42: 159-170 http://dx.doi.org/10.1016/j.jsames.2012.11.005

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