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| Crateromys ballik, Carpomys dakal & Batomys cagayanensis Ochoa, Mijares, Piper, Reyes & Heaney, 2021 Drawing by Velizar Simeonovski. |
Abstract
The 18 extant members of the Tribe Phloeomyini, the “cloud rats,” constitute an endemic Philippine radiation of arboreal herbivores that range in size from ca. 18 g to 2.7 kg, most occurring in cloud forest above 1,200 m elevation. Although calibrated phylogenies indicate that the Phloeomyini is estimated to have begun diversifying within the Philippines by ca. 10–11 million years ago, no extinct fossil species have been described, severely limiting our understanding of this distinctive radiation. Our studies of fossil and subfossil small mammal assemblages from the lowland Callao Caves complex in NE Luzon, Philippines, have produced specimens of Phloeomyini that date from ca. 67,000 BP to the Late Holocene (ca. 4,000 to 2,000 BP). We identify three extinct species that we name as new members assigned to the genera Batomys, Carpomys, and Crateromys, distinguished from congeners by body size, distinctive dental and other morphological features, and occupancy of a habitat (lowland forest over limestone) that differs from the high-elevation mossy forest over volcanic soils occupied by their congeners. Batomys cagayanensis n. sp. is known only from two specimens from ca. 67,000 BP; Carpomys dakal n. sp. and Crateromys ballik n. sp. were present from ca. 67,000 BP to the Late Holocene. These add to the species richness and morphological diversity of this endemic Philippine radiation of large folivores, and show specifically that the lowland fauna of small mammals on Luzon was more diverse in the recent past than it is currently, and that Luzon recently supported five species of giant rodents (ca. 1 kg or more). All three occurred contemporaneously with Homo luzonensis, and two, the new Carpomys and Crateromys, persisted until the Late Holocene when multiple exotic mammal species, both domestic and invasive, were introduced to Luzon, and new cultural practices (such as making pottery) became evident, suggesting that modern humans played a role in their extinction.
Keywords: biogeography, body size, extinction, fossils, Holocene, Luzon, oceanic islands, paleoecology, Pleistocene, zooarchaeology
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| Lower molar teeth of the new giant cloud rat, Carpomys new species (left), compared with the two living species of Carpomys (middle) plus their close relative, Musseromys (right). Photos by Lauren Nassef, Field Museum of Natural History |
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| Collage of fossil cloud rat teeth. Upper molars of Crateromys new species on the left. Lower mandibles on the right: top, Carpomys new species. Middle, Batomys new species. Bottom, Crateromys new species. Photos by Lauren Nassef, Field Museum of Natural History |
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| Artist’s conception of the three extinct cloud rats, based on their living relatives. From the top, Crateromys, Carpomys, and Batomys. Drawing by Velizar Simeonovski, Field Museum of Natural History |
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| Callao Cave interior. Photo by Patricia Cabrera |
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| Callao Cave excavation. Photo by A. Mijares |
Janine Ochoa, Armand S. B. Mijares, Philip J. Piper, Marian C. Reyes and Lawrence R. Heaney. 2021. Three New Extinct Species from the Endemic Philippine Cloud Rat Radiation (Rodentia, Muridae, Phloeomyini). Journal of Mammalogy. gyab023. DOI: 10.1093/jmammal/gyab023
Ang mga buot o “cloud rats” ay kabilang sa isang endemikong radiyasyon sa Pilipinas na tinatawag na tribong Phloeomyini. Ang salitang buot (buut/buwət) ay katawagang gamit sa ilang wika sa Cordillera at hilagang Luzon para sa mga cloud rat at mga kaanyong mammal na naninirahan o umaakyat sa mga punungkahoy. May labing-walong uri ng buot ang kasalukyang matatagpuan sa Pilipinas, at sila ay may timbang mula 18 gramo hanggang 2.7 kilo. Karamihan sa kanila ay naninirahan sa kagubatan na tinatawag na “cloud forest” na natatagpuan sa mga bundok na may elebasyon na higit sa 1,200 m. Base sa genetikong datos, tinatayang ang ninunong lipi ng mga buot ay nakarating sa Pilipinas 14 na milyong taon na ang nakalipas, ngunit dahil sa kakulangan ng mga fossil ay limitado ang ating kaalaman tungkol sa kanilang ebolusyon. Ang mga arkeolohikal na hukay sa iba’t ibang yungib ng Callao (probinsiya ng Cagayan, hilagang-silangang Luzon) ay nakapagtala ng mga fossil na buot na may edad na ~67,000 taon hanggang sa Late Holocene (~4,000–2,000 libong taon). Tatlong napuksang sarihay o species ang aming natuklasan, at base sa kanilang naiibang anyo at ekolohiya, sila ay ipinapangalan bilang bagong kasapi ng mga urihay na Batomys, Carpomys, at Crateromys. Ang Batomys cagayanensis n. sp. ay kilala lamang mula sa dalawang specimen na may edad na ~67,000 taong nakalipas. Ang Carpomys dakal n. sp. at Crateromys ballik n. sp. ay natagpuan sa mga suson ng lupa na may edad mula ~67,000 taon hanggang Late Holocene. Ipinapakita ng mga fossil na ito na mas maraming uri pa ng maliliit na mammal ang nabuhay noon kaysa sa ngayon, at ang Luzon ay minsang nagtaglay ng limang uri ng malalaking buot na may timbang na isang kilo o higit pa. Ang tatlong fossil na buot ay namuhay kasabay ng Homo luzonensis, isang bagong tuklas na uri ng tao noong Pleistocene. Ang Carpomys dakal at Crateromys ballik ay nabuhay hanggang Late Holocene at nalipol sa panahon kung saan iba’t ibang mga mammal na domestikado at ilang ang dinala ng tao sa Luzon; gayundin, lumitaw ang mga bagong tradisyon tulad ng pagpapalayok. Ipinapahiwatig nito na ang mga aktibidad ng modernong tao ay maaaring nagdulot ng kanilang pagkalipol.
biogeography, fossils, Holocene, Luzon, oceanic islands, pagkalipol (extinction), paleoecology, Pleistocene, sukat ng katawan (body size), zooarchaeology