Aegyptocetus tarfaG. Bianucci.
- A 40-million-year-old battle between a shark and whale has been found preserved in decorative limestone.
- The whale, which likely died as a result of the shark attack, represents a new species, Aegyptocetus tarfa.
- The shark victim represents a transitional evolutionary stage for whales, when they spent time on land and in water.
About 40 million years ago, a single shark in Egyptian waters snuck below a whale and attempted to rip it to shreds, but it wasn't entirely successful.
The shark-bit and torn apart whale, described in the latest Journal of Vertebrate Paleontology, was recently discovered as a stonecutter in Italy prepared to slice into decorative limestone.
The whale, whose last moments were painful ones, turns out to represent a new species, Aegyptocetus tarfa, which lived on land as well as in the sea.
Co-author Giovanni Bianucci of the University of Pisa's Department of Earth Sciences, told Discovery News it's probable that the shark attacked the whale as it was "diving, considering that the bite was on the abdomen"
Bianucci and co-author Phillip Gingerich of the University of Michigan's Museum of Paleontology and Department of Earth and Environmental Sciences determined that the shark bit into five of the whale's ribs, with the most significant damage occurring to its rear left side.
"The shape and position of these marks make it likely that they resulted from an individual shark attack," Bianucci said. "Probably the shark attacked from the rear and the left, an attack strategy also described for the extant white shark when attacking seals and sea lions."
The whale may have fought back, because the shark did not completely consume its target, eventually releasing it either dead or dying. Over millions of years the whale's body fossilized prior to being discovered by a shocked stonecutter from Italy who sliced it into decorative facing stone before realizing what he had found.
Normally scientists try not to cut such rare specimens, but since this one was already sliced, the researchers could see important details, enabling them to identify this as a transitional land-to-water whale. All whales evolved from a land animal that gradually started to rest, breed and give birth on land while feeding in the sea at other times.
Based on skull and skeleton measurements, Aegyptocetus weighed about 1,400 pounds when it was alive. Its teeth suggest that it primarily fed on fish.
This species lived in the middle of the great whale's move to permanent ocean life. That transition started about 55 to 50 million years ago. Modern baleen and toothed whales didn't evolve until around 30 million years ago.
Bianucci and Gingerich document how the newly found species displays characteristics of the transition, such as a retained sense of smell, which is usually lost in aquatic mammal lineages, the ability to haul itself out of water, and an enhanced ability to hear, with a better hearing than later and modern whales.
As for why whales chose the all-water life, the researchers suggest ample food might have been the irresistible draw. Gingerich explained that the whales probably first engaged in "scavenging of dead fish on a shoreline, then chasing dying fish in the water, then pursuing healthy fish farther offshore as well as the dying, and finally losing all ties to the land and becoming fully marine."
Anthony Friscia, a researcher in the Department of Integrative Biology and Physiology at the University of California, Los Angeles, told Discovery News that "the most amazing thing about this discovery is the way it (the fossil whale) was found."
"Not only was it fortuitous that it was spotted at all, but the fact that the skull was already sliced actually made it more useful," Friscia said, mentioning that the "slicing revealed one of the more amazing characters of the specimen: the presence of small, scroll-like bones in the nose, called turbinates, which speak to the smelling ability of the species."
For those with limestone in homes, it's possible that the stone contains prehistoric animal fossils like the shark and described whale, but few see them. Gingerich explained that the fossils weather away at the same rate as the limestone.
"You have to be looking right at the surface at the right spot to see that there are bones there," he said.