Fossil Of New Species Of Dwarf Buffalo From Philippines Described By American Museum Of Natural History Paleontologist And Colleagues

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Color drawing of newly discovered species of water buffalo
A color reconstruction of what B. cebuensis probably looked like. This drawing shows the extinct dwarf water buffalo in proportion to the tamaraw (a rare dwarf water buffalo that lives on the Philippine island of Mindoro); a full-sized water buffalo; and a human being. B. cebuensis, who once lived on the Philippine island of Cebu, shrunk due to island dwarfing, whereby some large mammals confined to an island shrink in response to evolutionary factors, such as less food and a lack of predators.
Illustration by Velizar Simeonovski, Courtesy of The Field Museum

A joint U.S. and Philippine research group, including American Museum of Natural History paleontologist John J. Flynn, has identified a new species of miniature buffalo from fossil remains found on Cebu Island in the Philippines. The extinct dwarf buffalo, named Bubalus cebuensis, is distinctive in its proportions and small size, estimated to stand only 2.5 feet tall at the shoulder and to weigh about 350 pounds (contemporary water buffalos stand six feet tall and can weigh up to 2,000 pounds). A different species of dwarf buffalo, Bubalus mindorensis (or tamaraw), lives today on Mindoro Island in the Philippines, but even this animal, which stands three feet tall and weighs close to 500 pounds, is large compared to B. cebuensis. It has not been possible to precisely date the fossil but it is unlikely to be more than a few tens of thousands of years old--from either the Pleistocene or Holocene Epochs.

Fossils are quite rare in the tropical environments of the Philippines, and this is the first fossil mammal of any age to be reported from Cebu Island. The fossil remains were found 50 years ago in a phosphate mine by engineer Michael Armas. He kept them safe for nearly four decades and then showed them to physician Hamilcar Intengan, who recognized their importance and brought them to The Field Museum for identification and study in 1995.

Although this is the first new species of fossil mammal to be described from the Philippines in nearly 50 years, the new finding indicates that more fossil species of this era could be recovered in this region. The research sheds light on the evolution of diminutive species living on islands and could provide insights into debates on the evolution of small-bodied species elsewhere in the tropics such as the proposed new hominid Homo floresiensis found on an Indonesian island. The results are described in the Journal of Mammalogy by Dr. Flynn, Chairman and Frick Curator in the American Museum of Natural History's Division of Paleontology, and colleagues Darin A. Croft of Case Western Reserve University (also a Museum Research Associate), Lawrence R. Heaney of The Field Museum, and Angel P. Bautista of the National Museum of the Philippines.

"Discovery of the first fossil mammal from Cebu Island documents the potential for uncovering more evidence of ancient diversity and extinction in this tropical region," Dr. Flynn said. "The recovery of this new extinct species of dwarf buffalo suggests that evolution on islands during climate and sea level changes contributed to the remarkable biodiversity of the Philippines."

"This new species certainly illustrates why it is important to make fossil specimens available for scientific study," Dr. Heaney said. "If Mr. Armas or Dr. Intengan hadn't passed these specimens along, we might never have discovered this species or had any idea that water buffalo once lived on Cebu Island."

"Finding this new species is a great event in the Philippines," Dr. Bautista said. "Only a few fossils of elephants, rhinos, pig, and deer have been found here previously. We have wonderful living biodiversity, but we have known very little about our extinct species from long ago. Finding this new fossil species will spur us to new efforts to document the prehistory of our island nation."

Foot bones -- Left metatarsals (foot bones) of Bubalus bubalis (or domestic water buffalo), Bubalus mindorensis (or tamaraw, a dwarf buffalo species that lives today on Mindoro Island in the Philippines) and Bubalus cebuensis (the new species of extinct dwarf buffalo identified by John J. Flynn of the American Museum of Natural History and colleagues at The Field Museum and Case Western Reserve University).

Credit: John Weinstein, The Field Museum

The partial skeleton of B. cebuensis includes left and right foreleg bones, a hind foot bone, two vertebrae, two molars, and two hooves. Though short and miniature in overall size, B. cebuensis was robust in stature, along the lines of a small tamaraw, and its teeth were unusually large relative to the size of its body.

B. cebuensis is the first well-supported fossil example of "island dwarfing" among cattle and their relatives. The small size of the new species is probably the result of where it lived--on an island. Previous studies have shown that other large mammal lineages tend to rapidly become smaller when they disperse to and are confined to an island, possibly due to a lack of predators (without predators, there is no advantage to being of large size to avoid being eaten) or limited food (smaller animals require less food). This finding supports the idea that the modern tamaraw also evolved its small size because it too occurs only on a small island. It could be that B. cebuensis was smaller than the living tamaraws because the extinct dwarf buffalo species lived on an even smaller island.

"Natural selection can produce dramatic body-size changes," said Dr. Croft, lead author of the new research paper. "On islands where there is limited food and a small population, large mammals often evolve to much smaller size."

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