Like wild horses, Mindanao was, in prehistoric times, home to mastodons and elephants, including rhinoceros. As part of the contiguous territory called southern Philippines, Davao region could have hosted a number of these land giants during the Pleistocene period.
It was German geologist Edmund Naumann who first stumbled on the molars of a giant animal while on a visit in Mindanao. Three years later, the fossil was attributed to a stegodont (the extinct subfamily of the elephants), an extinct relative of modern elephants and was scientifically named Stegodon mindanensis.
Naumann’s discovery was later cited in Henry Fairfield Osborn’s ‘Proboscidea: A Monograph of the Discovery, Evolution, Migration and Extinction of the Mastodonts and Elephants of the World,’ published in 1942, which provided a brief commentary on finding the proboscidean molars collected in 1859/60:
“If a true Stegodont, Stegodon mindanensis is even more progressive than S. airawana, because the valleys between the ridge-crests [of the molars] are entirely closed up; it compares somewhat more closely with Stegodon aurora, also an imperfectly known species possibly referable to Archidiskodon (meridionalis or the southern mammoth).”
The other claims assert that dwarf elephants once lived and survived in Luzon and Panay islands during the Pleistocene era.
On the other hand, it was German-Dutch G. H. R. von Koenigswald (1902–82), a paleontologist–geologist known for his research on hominins and Homo erectus in Java, who first described the Philippine rhinoceros (Rhinoceros philippinensis), an extinct member of the family Rhinocerotidae, by using two specimens (the other artefact coming from a larger stegodon) he had. The artefacts, though, were later misplaced or lost.
Von Koenigswald, to justify the arrival of rhinos in the south, argued that Mindanao once formed part of the Sunda shelf area. This suggestion, though, did not rest on available evidence. Moreover, through the decades more fossils attributed to the Philippine rhino, the larger version of the Sumatran rhinoceros, were found.
In 1935, he wrote, two smooth fragments of a large specialized Stegodon were unearthed in Manila, while a small elephant tooth, identified to be that of a pygmy elephant (Elephas beyeri, n. sp.) was found in Pangasinan in 1910.
On May 13, 1965, a certain de Asis found a fossilized jaw of the animal which he discovered in Fort Bonifacio area in Manila, from a deposit produced by a volcano called Guadalupe Formation. The rhino specimen, according to an online entry, was 12.07 cm (4.75 in) in length, 6.87 cm (2.70 in) in width, and 9.47 cm (3.73 in) in thickness, with a weight of 800 grams (28 oz).
The most vital archaeological find belonging to the species was the 2018 specimen of a nearly complete Philippine rhino fossil dug in Rizal, Kalinga province, which the scientists dated to around 709,000 years after the unearthed tooth enamel was exposed to electron spin resonance.
Significantly, the fossil, abandoned on a river floodplain, yielded key details: (i) there were butchery marks on the ribs, metacarpals and humeri and (ii) cut marks from stone blades were visible on the ribs and ankle, indicating someone used tools to strip the meat from the carcass.
Above all, paleontologists pointed to the early humans or hominins as behind the killing.
The new date for the initial occupation of the Philippines brought down an earlier claim that prehistoric Filipinos (though they were not yet known by that name then) were already living in the islands as evidenced by the finding of a 67,000-year-old foot bone at Callao Cave, in the town of Peñablanca, Cagayan province.
But there were also other exotic giant animals that used to inhabit the islands. The discovery of the toe bones in El Nido, Palawan, attributed to a tiger (Panthera tigris), formulated the theory that anywhere between 420,000 and 620,000 years ago, it reached Palawan via land bridges.
Another land mammal who settled in the islands was the pygmy water buffalo (Bubalus ceubensis), which was only 2.5 feet tall at shoulder height and weighed roughly 350 pounds (180 kg). It lived in the Cebu islands and smaller than the Mindoro tamaraw (Bubalus mindorensis).
“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,” American Museum of Natural History paleontologist John J. 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.”
The other extinct mammals that once roamed the islands during the Pleistocene era were the Luzon elephant (Stegodon luzonensis), Luzon giant tortoise (Megalochelys sondaari), Luzon water buffalo (Bubalus sondaari), dhole or wild dog (Cuon alpinus), Asian elephant (Elephas maximus), Palawan deer (Cervus sp.), and the wild boar scientifically known as Celebochoerus cagayanensis.
Moreover, in 2011, a team of Italian scientists found the remains of a 20-million-year-old fossil of a sea cow (Dugong dugon) species, also known as sirens, in a limestone rock above the waters of Puerto Princesa’s underground river. To-date, there are still two species of sea cow that exist, namely the dugong of the Indo-Pacific region and manatees of the Atlantic basin.
