The Early Holocene Vertebrate Faunas From Seropan Cave, Gunung Sewu, YOGYAKARTA, Indonesia

DOI: 10.17014/ijog.5.1.33-45An excavation of a vertebrate fossil site was carried out in 2012 in the Seropan Cave of Gunung Sewu karst area, Wonosari, Yogyakarta. Among the discovered mammal fossils there are Cervus sp., Sus verrucosus, Bubalus sp., and Panthera cf. pardus. Small mammal bone fragments of GSP (Gua Seropan/Seropan Cave) Nos. 38, 67, 91-113 have been analyzed for C14 radiocarbon age dating, which gave a date of 9,450 ± 400 yrs. B.P. or Early Holocene. The Seropan fauna is part of the succession series of Braholo fauna that migrated before the Late Pleistocene, and was isolated after the last Ice Age. The Seropan fauna developed and adapted their morphology to the local habitat

The effect of area and isolation on insular dwarf proboscideans

Aim We investigated the hypothesis that insular body size of fossil elephants is directly related to isolation and surface area of the focal islands. Location Palaeo-islands worldwide. Methods We assembled data on the geographical characteristics (area and isolation) of islands and body size evolution of palaeo-insular species for 22 insular species of fossil elephants across 17 islands. Results Our results support the generality of the island rule in the sense that all but one of the elephants experienced dwarfism on islands. The smallest islands generally harbour the smallest elephants. We found no support for the hypothesis that body size of elephants declines with island isolation. Body size is weakly and positively correlated with island area for proboscideans as a whole, but more strongly correlated for Stegodontidae when considered separately. Average body size decrease is much higher when competitors are present. Main conclusions Body size in insular elephants is not significantly correlated with the isolation of an island. Surface area, however, is a significant predictor of body size. The correlation is positive but relatively weak; c. 23% of the variation is explained by surface area. Body size variation seems most strongly influenced by ecological interactions with competitors, possibly followed by time in isolation. Elephants exhibited far more extreme cases of dwarfism than extant insular mammals, which is consistent with the substantially more extended period of deep geological time that the selective pressures could act on these insular populations

Quaternary vertebrate faunas from Sumba, Indonesia: implications for Wallacean biogeography and evolution

Historical patterns of diversity, biogeography and faunal turnover remain poorly understood for Wallacea, the biologically and geologically complex island region between the Asian and Australian continental shelves. A distinctive Quaternary vertebrate fauna containing the small-bodied hominin Homo floresiensis, pygmy Stegodon proboscideans, varanids and giant murids has been described from Flores, but Quaternary faunas are poorly known from most other Lesser Sunda Islands. We report the discovery of extensive new fossil vertebrate collections from Pleistocene and Holocene deposits on Sumba, a large Wallacean island situated less than 50 km south of Flores. A fossil assemblage recovered from a Pleistocene deposit at Lewapaku in the interior highlands of Sumba, which may be close to 1 million years old, contains a series of skeletal elements of a very small Stegodon referable to S. sumbaensis, a tooth attributable to Varanus komodoensis, and fragmentary remains of unidentified giant murids. Holocene cave deposits at Mahaniwa dated to approximately 2000–3500 BP yielded extensive material of two new genera of endemic large-bodied murids, as well as fossils of an extinct frugivorous varanid. This new baseline for reconstructing Wallacean faunal histories reveals that Sumba's Quaternary vertebrate fauna, although phylogenetically distinctive, was comparable in diversity and composition to the Quaternary fauna of Flores, suggesting that similar assemblages may have characterized Quaternary terrestrial ecosystems on many or all of the larger Lesser Sunda Islands

The effect of area and isolation on insular dwarf proboscideans

Aim: We investigated the hypothesis that insular body size of fossil elephants is directly related to isolation and surface area of the focal islands. Location: Palaeo-islands worldwide. Methods: We assembled data on the geographical characteristics (area and isolation) of islands and body size evolution of palaeo-insular species for 22 insular species of fossil elephants across 17 islands. Results: Our results support the generality of the island rule in the sense that all but one of the elephants experienced dwarfism on islands. The smallest islands generally harbour the smallest elephants. We found no support for the hypothesis that body size of elephants declines with island isolation. Body size is weakly and positively correlated with island area for proboscideans as a whole, but more strongly correlated for Stegodontidae when considered separately. Average body size decrease is much higher when competitors are present. Main conclusions: Body size in insular elephants is not significantly correlated with the isolation of an island. Surface area, however, is a significant predictor of body size. The correlation is positive but relatively weak; c. 23% of the variation is explained by surface area. Body size variation seems most strongly influenced by ecological interactions with competitors, possibly followed by time in isolation. Elephants exhibited far more extreme cases of dwarfism than extant insular mammals, which is consistent with the substantially more extended period of deep geological time that the selective pressures could act on these insular populations. © 2016 John Wiley & Sons Lt

Quaternary vertebrate faunas from Sumba, Indonesia: implications for Wallacean biogeography and evolution

Historical patterns of diversity, biogeography and faunal turnover remain poorly understood for Wallacea, the biologically and geologically complex island region between the Asian and Australian continental shelves. A distinctive Quaternary vertebrate fauna containing the small-bodied hominin Homo floresiensis, pygmy Stegodon proboscideans, varanids and giant murids has been described from Flores, but Quaternary faunas are poorly known from most other Lesser Sunda Islands. We report the discovery of extensive new fossil vertebrate collections from Pleistocene and Holocene deposits on Sumba, a large Wallacean island situated less than 50 km south of Flores. A fossil assemblage recovered from a Pleistocene deposit at Lewapaku in the interior highlands of Sumba, which may be close to 1 million years old, contains a series of skeletal elements of a very small Stegodon referable to S. sumbaensis, a tooth attributable to Varanus komodoensis, and fragmentary remains of unidentified giant murids. Holocene cave deposits at Mahaniwa dated to approximately 2000–3500 BP yielded extensive material of two new genera of endemic large-bodied murids, as well as fossils of an extinct frugivorous varanid. This new baseline for reconstructing Wallacean faunal histories reveals that Sumba's Quaternary vertebrate fauna, although phylogenetically distinctive, was comparable in diversity and composition to the Quaternary fauna of Flores, suggesting that similar assemblages may have characterized Quaternary terrestrial ecosystems on many or all of the larger Lesser Sunda Islands

Figure S5 from Quaternary vertebrate faunas from Sumba, Indonesia: implications for Wallacean biogeography and evolution

Toothrows and cranial elements of <i>Raksasamys tikusbesar</i>

Text S1; Text S2; Text S3; Table S1; Table S2; Table S3; Table S4; Table S5 and Table S6 from Quaternary vertebrate faunas from Sumba, Indonesia: implications for Wallacean biogeography and evolution

Fossils and dating of <i>Stegodon sumbaensis</i>.; Systematic palaeontology.; Phylogenetic placement of <i>Milimonggamys</i> and <i>Raksasamys</i>.; Caves on Sumba investigated for Quaternary fossils.; Toothrow lengths and mass estimates for Lesser Sunda murids.; Morphological character matrix of southeast Asian murids.; Maxillary tooth measurements for <i>Varanus hooijeri</i>.; Uranium-series isotope data from line analyses of <i>Stegodon</i> molar.; Uranium-series isotope data from spot analyses of Stegodon molar

Figure S8 from Quaternary vertebrate faunas from Sumba, Indonesia: implications for Wallacean biogeography and evolution

Activity ratios in <i>Stegodon</i> molar

Figure S4 from Quaternary vertebrate faunas from Sumba, Indonesia: implications for Wallacean biogeography and evolution

Toothrows and cranial elements of <i>Milimonggamys juliae</i>

Figure S7 from Quaternary vertebrate faunas from Sumba, Indonesia: implications for Wallacean biogeography and evolution

Cross-section of <i>Stegodon</i> molar showing line and spot analyses