Fossils identified as dwarf water buffalo

Nearly 50 years after a mining prospector found some fossilized bones on a remote Philippine mountain, they have been identified in Chicago as an extinct species of dwarf water buffalo, apparently shrunken in size after their much larger ancestors were left 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 buffalo that remain 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 about 350 pounds.

The little buffalo is a classic example of natural selection at work, say the four scientists who have studied the pint-sized remains, naming it Bubalus cebuensis in a scientific article published last month in the Journal of Mammalogy.

Among them is Larry Heaney, 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 to keep their energy up, 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 University and John Flynn of the American Museum of Natural History, and archeologist Angel Bautista of 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 cave-like 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.

Wondering 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.

In 1995, he met Dr. Hamlicar Intengan, a Philippine-born physician at Chicago’s St. Bernard Hospital who was visiting his family in Cebu. Seeing the bones, Intengan volunteered to take them to Chicago and find 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’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 that it was a buffalo -- but 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.

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 mindoroensis), a nearly extinct wild species found only on the Philippine island of Mindoro and about 20% 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 bones through radio carbon testing, Heaney said it was impossible to say when the new buffalo lived, though it would fit in a window between 100,000 and 20,000 years ago.

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 have seen in lots of large animals worldwide after groups of them became restricted to islands.”

Island dwarfism has been at the center of a hot scientific debate since scientists reported in 2004 that they had found remains of a colony of tiny people barely 3 feet tall who lived as recently as 18,000 years ago on the Indonesian island of Flores.

Some scientists think they represent a new human species, but others contend they are humans altered by the dynamics of island dwarfism. Indeed, their remains are found in context with dwarf elephants they once hunted and ate.