Nursery of giant extinct sharks

In what is believed to be a nursery of megalodons, an extinct giant shark species that lived between 17 and two million years ago, has been discovered in the Isthmus of Panama.

According to the scientists, megalodons -- the largest shark that ever lived -- had nurseries to raise young sharks typically in shallow areas where they can find ample food and protection from predators, mainly larger sharks, LiveScience reported.

"It is amazing how we were able to reconstruct a behavioural strategy used by ancient sharks based on fossils," said lead researcher Catalina Pimiento, a biologist at the University of Florida and the Smithsonian Tropical Research Institute.

"The findings reveal that sharks, even in their largest forms, have used nursery areas for millions of years as an adaptive strategy for their survival," Pimiento added.

These findings were based on the fossil teeth found in the Isthmus of Panama -- a marine strait that once connected the Pacific Ocean with the Caribbean Sea -- that was covered with shallow, salty waters some 82 feet deep.

According to the report, scientists investigating two 10-million-year-old fossil sites in the area found troves of megalodon teeth, roughly 400 in total.

Surprisingly, large megalodon teeth were uncommon in the troves. Instead, most ranged between 0.6 and 2.8 inches in length.

Based on the shapes of the little teeth, the researchers suggested they are from juveniles, as opposed to being small teeth from regular adults or coming from some dwarf species of megalodon.

For instance, some teeth possessed tiny sideway-jutting projections previously seen in young megalodons, while others were small, thick and heart-shaped, possibly coming from embryonic sharks.

All in all, the scientists found teeth from 21 juvenile megalodons some 6 to 34 feet long, as well as from seven adults, some of which were possibly mother sharks.

The researchers believe that the teeth could reach up to 6.6 inches long, while the megalodon could stretch more than 52 feet long. The foetuses alone could reach 13 feet in length, they said.

http://www.discoveryon.info/2010/05/nursery-of-extinct-giant-sharks.html