Bones unearth pygmy water buffalo

Tuesday, October 17, 2006

John Mangels

Plain Dealer Science Writer

Michael Armas was digging deep in a hillside when he found the strange-looking bones.

The handful of teeth, ribs and assorted other small skeletal pieces were scattered in the soft red clay at the bottom of the tunnel. Armas, a mining engineer by trade, had been hunting for phosphate, a valuable ore used in detergents and fertilizer. The bones were a distraction, but an interesting one.

They were partially fossilized, and fossils were a rarity in his native Philippines. The damp tropical heat tended to turn bones to mush.

Armas took the fossils home and put them in a jar. Sometimes he showed them to visitors, hoping someone would be able to tell him where the bones came from. No one could.

Nearly 40 years passed. Finally, Armas met a doctor, a fellow Filipino who practiced medicine in Chicago but had come back to see family on the little island of Cebu, where he and Armas had grown up. Surely, Armas said, one of the doctor's colleagues in the big city could figure out the bones' origin. The doctor agreed to try.

One day in 1997, he showed up at the Field Museum, Chicago's venerable natural history institution, carrying a box of bones. He left them with a guard, along with a note about their discovery in the Philippines.

People bring bones to museums fairly often, wondering if they've found something rare. "Most of the time, it's pork chops from somebody's dinner, that sort of thing," laughs Lawrence Heaney, the museum's curator of mammals. Not this time.

Heaney, an expert on the evolution of mammals in the Philippines, compared the fossils to samples in the museum's huge collection. They resembled the bones of a diminutive Filipino water buffalo called a tamaraw. But they were much smaller.

Heaney and his colleagues, including paleontologist Darin Croft of Case Western Reserve University, a specialist in extinct hoofed mammals, bore down on the mystery.

Today, almost half a century after Michael Armas pulled the curious bones from the earth, the research team will announce that the fossils are remnants of a previously unknown species of pygmy water buffalo. They've named it Bubalus cebuensis, for Cebu, the island where Armas made his discovery.

The extinct creature, heavier than a big dog but no taller, was a dramatically downsized version of its cousin, the hulking domestic water buffalo common to rice paddies in Asia. Its tiny stature was the result of an evolutionary quirk called "island dwarfing," nature's way of adapting body size to limited resources.

Scientists have documented the mechanism at work in isolated populations of elephants, hippos, deer, even perhaps ancient humans - but never before in the cattle family.

B. cebuensis probably evolved from full-sized water buffalo ancestors that lived on the Asian continent. During the ice age between 10,000 and 100,000 years ago, sea levels were as much as 400 feet lower than today. With narrower channels and more exposed land, able swimmers like water buffalo would have had little trouble making their way from the mainland to the Philippine is land chain.

Once they ar rived there, evolutionary forces unique to island populations would have come into play. Cebu is tiny, roughly the size of Delaware. Previous studies have uncovered a relationship between island size and animal body size. Smaller islands have less of a food supply than do continents, but they may also have fewer natural predators.

In that kind of setting, "small things, as a general rule, tend to get big, and big things tend to get small," Croft said.

Driven by natural selection, the dwarfing process may have taken only a few thousand years to play out, producing an animal that, judging by the fossils, stood less than 3 feet high and weighed about 350 pounds. Asian water buffalo, by contrast, stand 6 feet at the shoulder and weigh more than a ton.

Tooth wear and bone lengths confirm the fossil specimen was a full-grown adult rather than a juvenile, said Croft, who did extensive comparisons with samples at other museums.

B. cebuensis eventually died out; when and why is unclear, though the island's shift from grassland to forest as the climate warmed may have played a role.

There are no water buffalo on Cebu today. Nearby Mindoro, a somewhat larger island, is home to the larger tamaraw which, though endangered, survives today. The discovery of a pygmy species on Cebu "really lends support to the idea that the tamaraw is also an island dwarf," Croft said, and that there was progressive dwarfing as the large mainland water buffalo spread through the island chain.

All those insights stem from the curiosity of a man digging a tunnel.

"When you're that persistent, unlikely things become likely," Heaney said. "This is one of those moments that don't come along very often. It was wonderful."

To reach this Plain Dealer reporter:

jmangels@plaind.com, 216-999-4842



Bones unearth pygmy water buffalo Tuesday, October 17, 2006 John Mangels Plain Dealer Science Writer Michael Armas was digging deep in a hillside when he found the strange-looking bones. The handful of teeth, ribs and assorted other small skeletal pieces were scattered in the soft red clay at the bottom of the tunnel. Armas, a mining engineer by trade, had been hunting for phosphate, a valuable ore used in detergents and fertilizer. The bones were a distraction, but an interesting one. They were partially fossilized, and fossils were a rarity in his native Philippines. The damp tropical heat tended to turn bones to mush. Armas took the fossils home and put them in a jar. Sometimes he showed them to visitors, hoping someone would be able to tell him where the bones came from. No one could. Nearly 40 years passed. Finally, Armas met a doctor, a fellow Filipino who practiced medicine in Chicago but had come back to see family on the little island of Cebu, where he and Armas had grown up. Surely, Armas said, one of the doctor's colleagues in the big city could figure out the bones' origin. The doctor agreed to try. One day in 1997, he showed up at the Field Museum, Chicago's venerable natural history institution, carrying a box of bones. He left them with a guard, along with a note about their discovery in the Philippines. People bring bones to museums fairly often, wondering if they've found something rare. "Most of the time, it's pork chops from somebody's dinner, that sort of thing," laughs Lawrence Heaney, the museum's curator of mammals. Not this time. Heaney, an expert on the evolution of mammals in the Philippines, compared the fossils to samples in the museum's huge collection. They resembled the bones of a diminutive Filipino water buffalo called a tamaraw. But they were much smaller. Heaney and his colleagues, including paleontologist Darin Croft of Case Western Reserve University, a specialist in extinct hoofed mammals, bore down on the mystery. Today, almost half a century after Michael Armas pulled the curious bones from the earth, the research team will announce that the fossils are remnants of a previously unknown species of pygmy water buffalo. They've named it Bubalus cebuensis, for Cebu, the island where Armas made his discovery. The extinct creature, heavier than a big dog but no taller, was a dramatically downsized version of its cousin, the hulking domestic water buffalo common to rice paddies in Asia. Its tiny stature was the result of an evolutionary quirk called "island dwarfing," nature's way of adapting body size to limited resources. Scientists have documented the mechanism at work in isolated populations of elephants, hippos, deer, even perhaps ancient humans - but never before in the cattle family. B. cebuensis probably evolved from full-sized water buffalo ancestors that lived on the Asian continent. During the ice age between 10,000 and 100,000 years ago, sea levels were as much as 400 feet lower than today. With narrower channels and more exposed land, able swimmers like water buffalo would have had little trouble making their way from the mainland to the Philippine is land chain. Once they ar rived there, evolutionary forces unique to island populations would have come into play. Cebu is tiny, roughly the size of Delaware. Previous studies have uncovered a relationship between island size and animal body size. Smaller islands have less of a food supply than do continents, but they may also have fewer natural predators. In that kind of setting, "small things, as a general rule, tend to get big, and big things tend to get small," Croft said. Driven by natural selection, the dwarfing process may have taken only a few thousand years to play out, producing an animal that, judging by the fossils, stood less than 3 feet high and weighed about 350 pounds. Asian water buffalo, by contrast, stand 6 feet at the shoulder and weigh more than a ton. Tooth wear and bone lengths confirm the fossil specimen was a full-grown adult rather than a juvenile, said Croft, who did extensive comparisons with samples at other museums. B. cebuensis eventually died out; when and why is unclear, though the island's shift from grassland to forest as the climate warmed may have played a role. There are no water buffalo on Cebu today. Nearby Mindoro, a somewhat larger island, is home to the larger tamaraw which, though endangered, survives today. The discovery of a pygmy species on Cebu "really lends support to the idea that the tamaraw is also an island dwarf," Croft said, and that there was progressive dwarfing as the large mainland water buffalo spread through the island chain. All those insights stem from the curiosity of a man digging a tunnel. "When you're that persistent, unlikely things become likely," Heaney said. "This is one of those moments that don't come along very often. It was wonderful." To reach this Plain Dealer reporter: jmangels@plaind.com, 216-999-4842 © 2006 The Plain Dealer © 2006 cleveland.com All Rights Reserved.