Present-day piranhas have a single row of triangular teeth, like the blade on a saw, explained the researchers. Pacu have two rows of square teeth, presumably for crushing fruits and seeds.
"In modern piranhas, the teeth are arranged in a single file," said Wasila Dahdul, a visiting scientist at the National Evolutionary Synthesis Center in North Carolina. "But in the relatives of piranhas — which tend to be herbivorous fishes — the teeth are in two rows."
The new fossil shows an intermediate pattern: teeth in a zig-zag row. This suggests that the two rows in pacu were compressed to form a single row in piranhas. "It almost looks like the teeth are migrating from the second row into the first row," said John Lundberg, curator at the Academy of Natural Sciences in Philadelphia and a co-author of a study of the jawbone.
Friday, June 26, 2009
Wednesday, June 24, 2009
The long-term digging effort in Rione Terra, a cliff in the port town of Pozzuoli, has yielded remains of 12 ancient statues, columns, and fragments bearing inscriptions from what appear to be monuments from the Republican and Imperial periods of ancient Roman history.
Among the most striking finds was the marble head of Emperor Titus, who ruled at the time of the eruption of Mount Vesuvius in 79 A.D. and who was celebrated throughout antiquity for providing generous financial assistance to survivors of the eruption. Bearing a crown of laurel leaves, the emperor's head was found in an ancient water tunnel.
Props to MSNBC for the photo via Soprintendenza speciale per i beni archeologici di Napoli e Pompe