Stegodon Research Articles

The Late Quaternary palaeogeography of mammal evolution in the Indonesian Archipelago

The Quaternary faunal evolution for the Indonesian Archipelago reflects the unique relationship of each island with SE Asian mainland. The recent sub faunas of Sundaland (Kalimantan, Sumatra, Java, and Bali) preserved broad connections with the SE Asian mainland during the latest glacial. They are all balanced and show many mainland components. Alternatively, Wallacea (Sulawesi and the Lesser Sunda Islands) has always been geographically isolated from the mainland. Wallacea faunas thus remain unbalanced (they lack large carnivores) and endemic. A significant turnover arrives throughout the region with pronounced global sea level recessions around 0.8 Ma, during the transition from Early Pleistocene (EP) to the Middle Pleistocene (MP). By way of comparison, the palaeontological records of Japan and Taiwan also preserve this turnover, with EP–MP recessions bringing East Asian mainland immigrants. On Java, the earliest, Late Pliocene to early Pleistocene Satir fauna indicates island conditions. Java became connected to the SE Asian mainland towards the end of the early Pleistocene. Global cooling brought open woodlands on Java, an environment evidently preferred by Homo erectus in the Ci Saat fauna and Trinil H.K. fauna. As EP–MP sea level recessions created a wide corridor across the Sunda Shelf, Siwaliks and the SE Asian mainland terrestrial mammals invaded, as is seen in the Kedung Brubus fauna. The succeeding Ngandong fauna maintains an open woodland character but shows some endemism ( Homo erectus and Stegodon trigonocephalus, among others, can be distinguished on a subspecies level). The Late Pleistocene marks the earliest known tropical rainforest, and the corresponding Punung fauna is of Chinese affinity (with Pongo, Hylobates, and Elephas maximus). Homo sapiens probably arrives at this point as well. The youngest fossil faunas known from Java are the still poorly known Cipeundeuy Fauna (ca. 30 ka) and the Holocene faunas from Wajak and Sampung. While Sulawesi and Flores remained isolated throughout the Quaternary, only a limited number of terrestrial vertebrates arrived by crossing sea barriers. Endemic island faunas with pygmy elephantoids and giant tortoises were present during the Early Pleistocene. EP–MP sea level recessions allowed large to medium sized elephantoids to replace the dwarf species. Around the same time, Homo erectus appears on the island of Flores. Modern faunas eventually replaced the Middle Pleistocene island faunas, but the time frame has yet to be pinpointed. Sulawesi presents a unique case. Its current fauna holds no Walanae representatives. Apart from the phalangers, which must have come from the east. The ancestors of all other large Sulawesi land vertebrates, fossil and extant, reached the island by crossing the Sunda Sea. As the South Sulawesi fauna was stable until the Middle Pleistocene, this area must have constituted a separate palaeo-island. Some localized developments can be observed (e.g. shortening of the metapodials in Celebochoerus, increasing hypsodonty in Stegodon).

Immigration times of the two proboscidean species, Stegodon orientalis and Palaeoloxodon naumanni, into the Japanese Islands and the formation of land bridge

Immigration times of the two proboscidean species, Stegodon orientalis and Palaeoloxodon naumanni, into the Japanese Islands and the formation of land bridge

The Solution of the Cryptomastodon Problem

Cryptomastodon martini Von Koenigswald from the Pleistocene of Java is based upon two molar fragments and a humerus portion. The molar fragments originally described as Mastodon by Martin and by Van Es are referable to Stegodon trigonocephalus Martin. The humerus portion described as Problematicum by Stehlin belongs to the giant land tortoise Geochelone atlas (Falconer & Cautley). As the material upon which Cryptomastodon martini has been based represents two already named taxa this name must be sunk.

Tephrochronological study on the middle Pleistocene deposits in the Kanto and Kinki districts, Japan

The middle Pleistocene time range is defined here the period before the last interglacial in the Brunhes epoch. In Japan, the Shimosa-Kazusa Groups around the Tokyo Bay in Kanto and the upper part of the Osaka Group in Kinki both represent the standard middle Pleistocene sequences and have been studied in detail. These groups are characterized by the cyclic sedimentation caused by transgression and regression corresponding to climatic changes.The purpose of this paper is to attempt the correlation of the Kazusa Group and the Osaka Group by identification of widespread marker-tephras. Accurate determinations of the refractive indices of volcanic glass, orthopyroxene and hornblende, together with other determinations, have enabled successful characterization for correlation to be made for several tephra layers in southern Kanto and Kinki. The following marker-tephras are found over two districts, resulting in the establishment of several important datum planes in the middle Pleistocene sequences.The vitric tephra called Ks 11, which is sandwiched in the Kasamori Formation and its correlatives in southern Kanto, can be identified as a marker tephra of the Osaka Group called Sakura ash, in the vicinity of Osaka and Kyoto. The estimated age of this tephra, about 450, 000 years, is based on its stratigraphic relationship with the underlying dated tephra, Kinukawa ash (460, 000-470, 000 years). Stratigraphically, it is included in the deposits immediately below the transgressive horizon (Tama-f and Ma 7) and also occurrs in the biozone of Stegodon orientalis in both districts. The vitric tephra called Ku 1, sandwiched in the Kokumoto Formation, is identified and correlated with a tephra called Imakuma I ash. It is included in the deposits immediately above the Brunhes-Matuyama boundary. The very important dated tephra, Azuki ash (870, 000 years), in the Osaka Group, can be correlated with Ku 6C tephra in the lower part of the Kokumoto Formation by their peculiar petrographic properties. Both are sandwiched in the deposits below the Brunhes-Matuyama boundary.From the relationship between the identified tephras and marine sequences, it is concluded that during the period from 700, 000 years to 450, 000 years at least three interglacial-glacial cycles are recorded, and that after 450, 000 years the following major interglacial episodes are indicated; 450, 000YBP, 370, 000YBP, 300, 000YBP, 230, 000YBP, and 130, 000YBP.

Relation of Pleistocene Migrations of Pygmy Stegodonts to Island Arc Tectonics in Eastern Indonesia

PLEISTOCENE pygmy stegodonts have been described from the Indonesian islands of Sulawesi, Flores and Timor1–4 which are now separated by deep seas. Hooijer4 suggested that the two forms Stegodon trigonocephalus florensis and Stegodon timorensis apparently coexisted in Flores as well as in Timor, although they may not have been strictly contemporaneous. He concluded that the dwarfing Stegodon populations wandered back and forth between Flores and Timor during the Pleistocene, because otherwise it is hard to see how the two evolutionary products on Timor and Flores could have been so similar. Flores is now separated from Timor by a 3,000 m deep Savu Sea 150 km wide which narrows to 30 km in the Ombai Strait between Alor and Timor (Fig. 1). Because an elephant (and presumably a stegodont) could not swim across the Savu Sea and Ombai Strait, the existence of a land connexion between Flores and Timor during the Pleistocene must be postulated (Fig. 1).

Correlation of the lower Pleistocene deposits in the Kantô and Kinki districts

Progress in the tephrostratigraphy in Kanto and Kinki for years made it possible to correlate the Plio-Pleistocene Kazusa group in South Kanto with the Osaka group and its correlatives in Kinki. In this paper the writer tried to correlate both groups by fossil elephants, fossil plants and paleomagnetic polarity of the deposits. Both Kazusa and Osaka groups lying below the biozone of Elephas naumanni yield Stegodon orientalis in the upper part. On the other hand, Stegodon shodoensis akashiensis is reported from the Lower part of the Osaka group, and molars of Parastegodon cf. aurorae which is an allied species of S. akashiensis were found at the middle and upper horizon of the Umegase formation (middle part of the Kazusa group) in Tama Hills. Moreover, in the Boso Peninsula the Umegase formation yields some specimens of Parelephas proximus which is thought to be closely related with Elephas shigensis from the Lower part of the Osaka group. Based upon these facts the correlation between the Kazusa and the Osaka groups is shown in the Table 1. As for the plant remains the Lowest part of the Osaka group is characterized by many species belonging to the Metasequoia flora. In South Kanto the Metasequoia flora has been reported from several horizons of the Kazusa group in Tama Hills which are correlated with the Umegase (or partly Otadai) horizon in Boso. According to the ONISHI's investigation into the pollen flora of the Kazusa group in Boso the group is divided into six pollen zones, and the correlation by the pollen zones of the Kazusa group with those of the Kinki district was carried out (Table 2).Paleomagnetic stratigraphy was investigated through successive measurements of DRM of the late Cenozoic formations of Boso and of NRM of the volcanic ash layers interbedded in the Osaka group and its correlatives together with fission-track dating of some ash layers. The boundary between the Brunhes and Matsuyama epochs is correlated with the middle horizon of the Kokumoto and the lowest horizon of the Upper part of the Osaka group. The Jaramillo event corresponds either to the middle Kokumoto or to the upper horizon of the Lower part of the Osaka group. Moreover, the Olduvai event is correlated with the middle horizon of the Umegase and with the boundary between the Lower and Lowest of the Osaka group. The correlation by the paleomagnetic polarity is shown in Table 3.

Sea-level and Altitude of Land Bridges during the Continental Stages of Japan

The fossil record and distribution of the Recent terrestrial fauna indicate that at some time during the Quaternary Japan had a land connection with Asiatic continent. The fossil mammals from the Nagahama Formation of the Boso Peninsula include Stegodon orientalis which is thought to be a warm temperature species from its distribution. This elephant must have migrated to Japan during a warm climate stage and probably of high sea-level. Land connection with the Asiatic continent is expected not only during the low sea-level stage but also during the high sea-level stage of the Early Pleistocene. The Middle and Late Quaternary eustatic oscillations of sea-level based on the terraces developed and distributed along the coast and off shore of Japan are shown in the text-figure, in which the idealized projected profiles of the terraces are in the left and the thickness of the conformable marine Pleistocene formations distributed and developed in the northern part of the Boso Peninsula whose top corresponds with the sea-level in the stage III in the right. The land connection is expected throughout the Middle and Late Quaternary except for stages of III and I, which are preceded by the low sea-levels.The land connection problem is geographical and biological in nature, and diastrophism may be concerned. The geological structure and topography of the Korean Strait and its vicinity suggest some probability of the isolation of Japan from the Asiatic continent due to diastrophism.

Stratigraphical and geographical distribution of Fossil Elephants in Kinki District, Central Japan

Twenty-eight localities of fossil elephants (Stegodon and Elephas) have hitherto been known in the Pliocene-Pleistocene formations of the Kinki District, Central Japan. By checking these fossils and their geological occurrences, the writer obtained the following stratigraphical succession of these elephant-bearing horizons: Age in lettersHorizon I Stegodon elephantoides H2 (Pliocene)Horizon II {Stegodon insignis sugiyamai Stegodon shodoensis shodoensis akashiensis I1 (Pliocene?)Horizon III {Elephas namadicus naumanni Stegodon orientalis I2 (Low. Pleistoc.) Horizon IV Elephas namadicus naumanni J2 (Pleistoc.)

109., On Two Teeth of Elephants found in Niigata-Prefecture (Resume)

As fossil elephants have not been known from the prefecture except Stegodon orientalis shodoensis described by H., MATSUMOTO, the present occurrences are of special interest., The one discovered in the Wanazu sandstone formation at Okada, Takayanagi-mura, Kariha-gun is Parastegodon cf., akasiensis and the other found in the Oguni brown coal bearing formation at Sizyuppo, Tatibana-mura, Naka-Uonuma-gun, is Palaeoloxodon namadicus naumanni., In regard to the horizons which yielded the fossils, the former is indicative of the early Pleistocene age and the latter of the late Pleistocene., Since Pleistocene deposits are not very well represented in the region and opinion has generally been that the Wanazu sandstone formation is late Pliocene, the find of Pleistocene mammalian remains provides important keys for future research., Finally it may be noted that MATSUMOTO's specimen may possibly be misidentified for it appears to me to be identical with Parastegodon cf., akashiensis.,

Early Man in Java

A COMMUNICATION by Dr. P. V. van Stein Callenfels to the Royal Anthropological Institute, which appears in summary form in Man of December, urges the desirability of reconsidering the age and standing of Pithecanthropus. Dr. Callenfels has classified the fossil fauna of the Java Pleistocene into three groupsearly, middle and late Pleistocene. Among those of the early Pleistocene are Stegodon cf. precursor (between Tertiary prcecursor and Middle Pleistocene trigonocephalus), Hippopotamus antiquus, Leptobos, three antelopes and marine molluscs, of which at least 30 per cent are extinct; Middle Pleistocene Stegodon trigonocephalus, Hippopotamus namadicus, Bos (Bubalus) bubalis palceokarabau, Axis axis lydekkeri (abundant), Duboisia (antelope); Late Pleistocene Stegodon trigonocephalus, Hippopotamus namadicus, Bos (Bubalus) Axis axis lydekkeri (very rare), Axis axis javanicus (abundant).

17., On the Genus Parastegodon

Parastegodon is a valid genus, though it little differs from the genus Stegodon, and soecialization is continuous from one to another., Japanese species of Parastegodon are closely related to the Malayan forms of the so-called Stegodon (mindanensis, trigonocephalus and airawana); the latter like the former are distinct from the genotype of Stegodon., Parastegodon contains the following species; P., aurorae (MATSUMOTO), P., mindanensis (NAUMANN) MATSUMOTO, P., infrequens SHIKAMA and P., kwantoensis TOKUNAGA., From dental and cranological characters, Parastegodon is classified into three groups of airawana, akashiensis-aurorae and infrequens-kwantoensis., It is an oriental stock, having intermediate characters between Stegodon and Archidiskodon., In Japan it seems to have dissappeared at the end of the Tertiary owing to its catagenetic declination.,