Nearly 50 years after a prospector found some mysterious fossilized bones on a remote Philippine mountain, they have been identified in Chicago as those of an extinct species of dwarf water buffalo, apparently shrunken in size after their much larger ancestors were isolated on a small island.
The bones of the animal, until now unknown to science, are an almost perfect copy in miniature of bones from the huge water buffaloes that remain the stalwart beasts of burden for farmers throughout Asia. An adult water buffalo can stand 6 feet high at the shoulder and weigh more than 2,000 pounds, but the newly identified buffalo was only about 2 1/2 feet high and weighed about 350 pounds.
The little buffalo is a classic example of natural selection at work, say the four scientists who have studied the remains of the animal, which they named Bubalus cebuensis in a scientific article published Tuesday in the Journal of Mammalogy.
One of the scientists, Larry Heaney, is the Field Museum’s curator of mammals and a world authority on the biological phenomenon called “island dwarfism.”
One theory behind that phenomenon attributes size reduction to limited food supplies, Heaney said. On an island, the larger animals of a species would have trouble finding sufficient nourishment while smaller individuals would have an easier time. Thus the smaller individuals would be more successful breeders, and genes favoring smaller stature would determine future generations.
The article’s four authors–the others are paleontologists Darin Croft of Case Western Reserve University (the name as published has been corrected in this text) and John Flynn of the American Museum of Natural History and archeologist Angel Bautista of the National Museum of the Philippines–credit two Filipino men with finding the fossil and bringing it to their attention. In 1958, Michael Armas was a young mining engineer prospecting for phosphate deposits on his home island of Cebu in the central Philippines when he found the bones in a cavelike depression on a forested limestone mountain slope formed from ancient coral reefs. The partial skeleton consisted of two teeth, two vertebrae, two upper arm bones, a foot bone and two hoof bones.
Puzzled by what animal they represented, Armas kept the bones at his home, seeking out scholars and showing the bones whenever he could, hoping for an answer.
Bones land in Chicago
In 1995, he met Dr. Hamilcar Intengan, a Philippine-born physician at Chicago’s St. Bernard Hospital and Health Care Center who was visiting his family in Cebu. Seeing the bones, Intengan volunteered to take them to Chicago for an expert opinion.
“One day he showed up at our north entrance with the bones packed in a box,” said Heaney. “The guard said he would look for somebody to help him, but after a few minutes he looked up and saw Intengan had left, leaving the box with a note.”
The bones made it to the Field Museum’s geology labs, but paleontologists there were unfamiliar with Philippine animals. Paleontologist Flynn asked Heaney, who specializes in fauna of the Philippines, to look.
Heaney quickly established it was a buffalo–just a smaller one than anyone had seen before. “It took me about 15 minutes to figure it out,” he said.
As often happens in busy labs, Heaney had to put the fossil aside to tend to more pressing research, but he eventually asked Croft, a post-doctoral research associate then at the Field, to zero in on Bubalus cebuensis.
2nd known dwarf buffalo
The new species is the second known dwarf buffalo to have evolved in the Philippines, said Croft, who was the lead author of the journal article. The other is the tamaraw (Bubalus mindorensis),a nearly extinct species found only on the Philippine island of Mindoro that is about 20 percent bigger than its late cousin from Cebu.
“Cebu is a smaller island than Mindoro,” said Croft, “and 30 years ago Larry Heaney postulated there might be a correlation between the body sizes of these dwarf animals and the size of the island they are confined to. The trend we see in the evidence is that the smaller the island is, the smaller the animal becomes.”
Because it is not possible to date the age of the bones through carbon dating, Heaney said it is impossible to say when the small buffalo lived, though it would probably be between 100,000 and 20,000 years ago.
About 20,000 years ago, he said, seas separating many of the Philippines’ more than 7,000 islands dried up during a global ice-age event, allowing land animals to migrate from one area to another. When the climate warmed and the seas refilled, each island’s animals went on their own evolutionary paths.
`Exciting discovery’
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The dwarf buffalo “is quite an exciting discovery,” said Erik Rickart, curator of vertebrates at the Utah Museum of Natural History. “It fits into a pattern we see in lots of large animals worldwide after groups of them became restricted to islands.”
Island dwarfism has been at the center of debate since scientists reported in 2004 that they had found remains of a colony of people barely 3 feet tall who lived as recently as 18,000 years ago on the island of Flores in Indonesia.
Some scientists believe those people represent a new human species, but others contend they are humans altered by the dynamics of island dwarfism.
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