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Lufengpithecus keiyuanensis from the Xiaolongtan Coal Mine is the earliest known Miocene fossil hominoids in southern China, yet its chronological context has long been subjected to disputes, in being either of late Middle Miocene or early Late Miocene age. This controversy is largely due to the uncertainty of the exact positions of previously discovered fossils in the outcrops, and the different chronological interpretations for some proboscidean and suid fossils from associated fossil faunal assemblages. Here we report the first discovery of Stegolophodon latidens from Xiaolongtan with an unambiguous stratigraphic provenance, which provides important evidence in constraining the age of Lufengpithecus keiyuanensis . Stegolophodon has a very high evolutionary rate of dental morphology, and exhibits a pronounced evolutionary trend with time: from the pentalophodont m3 of the Early Miocene or early Middle Miocene, to the pentalophodont M3 and hexalophodont m3 of the late Middle Miocene, to the 5.5-lophed (five principal lophs followed by an extreme well-developed cingulum) M3 and hexa- to heptalophodont m3 of the early Late Miocene, and to the hexalophodont M3 and hepta- to octalophodont m3 of the middle Late Miocene. The newly discovered Stegolophodon latidens bears a 5.5-lophed M3 and a heptalophodont m3, the second and subsequent lophs/lophids show a slight chevron structure, and the pretrite mesoconelets shift mesially and fuse with the corresponding pretrite anterior central conules, forming a “Y-shape”. These traits are similar to, or even slightly more derived than those of Stegolophodon from the lower part of the Dhok Pathan Formation (9.3−8.3 Ma) in the Middle Siwaliks of the Indian Subcontinent. The materials described here can all be assigned to Stegolophodon latidens which was originally discovered from the Yenangyaung fauna, the lower Irrawaddy Formation of Myanmar, deemed of early Late Miocene age. Revisions on the other proboscidean and suid materials also support an early Late Miocene age for Xiaolongtan Fauna. The new fossils were discovered from the upper part of the lignite layers, close to the bottom of the greyish marls of the Buzhaoba Formation. Based on the original records in the geological reports of the Xiaolongtan Coal Mine, the descriptions of the previous publications, as well as the accounts of the fossil finders, the Xiaolongtan coal mine possesses only one fossiliferous layer, which locates in the upper part on the Xiaolongtan Formation (lignite layers). Therefore, the new fossils situate possibly in the same layer as Lufengpithecus keiyuanensis that were found in the 1950’s and 1980’s. From the recent palaeomagnetic investigations, the age of this fossil layer should be 11.6/11.7 Ma, close to the boundary between the Middle and the late Miocene; however, seems to be slightly older than Stegolophodon latidens from the Siwaliks. Further investigations should be carried out to resolve this inconsistency.

The new fossil teeth of Stegolophodon (Proboscidea, Mammalia) were discovered from the terrestrial sediments of the Irrawaddy Formation, in Kyauksaungsan and Tebingan areas, Magway Region, central Myanmar. A new Stegolophodon species is established in this paper. Stegolophodon iravaticus shares the characters of the advanced Stegolophodon and the primitive Stegodon. The M3 of S. iravaticus is related to that of the molar of Sand Pit in Tha Chang, Thailand and that of from Dhedari, Pakistan which is included in the Stegolophodon group 6 of Saegusa et al. (2005).

We describe two well-preserved mandibles of Stegolophodon pseudolatidens (Mammalia, Proboscidea, Stegodontidae) discovered from the lower Miocene (ca. 16.9–16.6 Ma) in Northeast Japan. The mandible of Sl. pseudolatidens is primitive within the Stegodontidae in having a short symphysis with lower tusks, tetralophodont lower molars, and a mandibular canal with the large dorsoventral diameter in the anterior segment. It is characterized by a perpendicular mandibular ramus (forming an almost right angle between the anterior margin of the mandibular ramus and the dorsal horizontal surface of the corpus), and many scratches in mesial direction on the occlusal surface of m3, implying that Sl. pseudolatidens appears to have acquired a proal jaw movement during mastication. While the mandibular morphology of Sl. pseudolatidens is comparable to that of other species of the genus that of Stegolophodon cf. stegodontoides from the upper Miocene of Myanmar differs from that of these species in having a shorter symphysis, which is a derived condition.

Tetralophodont gomphotheres, i.e., Tetralophodon, Paratetralophodon, and Anancus, show significant morphological diversity and are of great importance for the biostratigraphy of the Upper Miocene. However, material of this group from the Upper Miocene of northern China is rare and easily to be confused with the similar taxa such as Konobelodon and Stegolophodon. The stratigraphy of this group is also unclear in China. Here we described the first mandible from northern China that can be definitely attributed to Tetralophodon, and erected a new species Tetralophodon euryrostris n. sp. Furthermore, we amended the previously reported tetralophodont gomphotheres from northern China. We attributed the type material of “Tetralophodon exoletus” to ?Paratetralophodon exoletus, the material from Lantian region (“Tetralophodon exoletus”) to Paratetralophodon sp., and the material from the Qaidam Basin (Tetralophodon sp.) to Tetralophodon aff. xiaolongtanensis. We also discussed the stratigraphic ranges of the tetralophodont proboscideans from the Upper Miocene of China, that is, Tetralophodon aff. xiaolongtanensis from MN9, Tetralophodon cf. euryrostris from MN10, Konobelodon robustus from MN9–MN10, Paratetralophodon sp. from MN11, ?Paratetralophodon exoletus from MN12, and Stegolophodon licenti from MN13. This work is important for the study of the taxonomy and biostratigraphy of tetralophodont gomphotheres from the Upper Miocene of northern China.

The dental evolution of Mammuthus during the Quaternary represents the ultimate level of adaptation to open habitats among all proboscideans. This is the end result of the increased trend in grazing ability in Elephantidae. The combination of mesiodistally flat molar plates and proal (from back to front) jaw movement allowed elephants to increase their grazing effectiveness to an extent that gomphotheres failed to achieve. This does not necessarily mean that this feature evolved as an adaptation to grazing. The acquisition of proal jaw movement in Elephantidae is not well delineated because of the poor fossil record of the earliest elephants. However, it seems that proal jaw movement can be developed independent of the adaptation to grazing. Stegolophodon from the Early Miocene of Japan (ca. 17.3 Ma) suggest that proal jaw movement was fully developed in stegolophodonts by 17.3 Ma. This date roughly coincides with the onset of the Miocene climatic optimum, but forested habitats remained in Southeast Asia and Japan. Thus, at that time, there was no climatic change that selected stegolophodonts to adapt to grazing. Stegodonts remained brachydont throughout their history. Stable carbon isotope data suggest that stegodonts had not become grazers before the latest Pliocene, and this may explain the differences between Elephantidae and Stegodontidae in molar height increase. On the other hand, the browsing habitat of most stegodonts fails to explain the increased number of loph(id)s in stegodonts subsequent to the latest Miocene.

Twenty mammalian fossil specimens of varying preservational state are described from the Chinji Formation of Dhulian, Pakistan. The remains described in this study are all teeth and represent the Proboscidea, Perissodactyla and Artiodactyla. All the dental specimens are new variants recorded here for the first time. Pliotriplopus dhulianensis is new to science having small size and absence of crista than Pliotriplopus chinjiensis. These findings extend the geographic distribution of this dentally highly derived Triplopinae, which was previously restricted to a single species, Pliotriplopus chinjiensis. Additional fossils of the three mammalian orders are necessary to shed new light on the phylogenetic relationships within the first representatives of the orders in Eurasia. A very important, deciduous tooth of the species Stegolophodon cautleyi hitherto unknown is described in this report.

The primitive deer (subfamily Lagomerycinae) Lagomeryx and Stephanocemas are characterized primarily by their palmate antlers. Two lagomerycines, Lagomeryx manai, sp. nov., and Stephanocemas rucha, are described for the first time from Q and K coal layers of the late middle Miocene (13.4–13.2 Ma) Mae Moh Basin in northern Thailand. A species-level phylogeny of the Ligeromeryx-Lagomeryx clade, based on cranial appendages, reconstructs Lagomeryx manai, n. sp., as a derived species of Lagomeryx, sister group of Lagomeryx complicidens. This study suggests that the large species of Lagomeryx are restricted geographically to Asia and dispersed to Southeast Asia at the latest during late middle Miocene, where they are represented by Lagomeryx manai, n. sp. The paleoenvironmental studies of five Mae Moh mammalian taxa, a cervid (Lagomeryx manai, n. sp.), an indeterminate bovid, a suid (Conohyus thailandicus), a rhinoceros (Gaindatherium sp.), and a proboscidean (Stegolophodon sp.), investigated with stab...

Recent fieldwork in the Miocene basins of northern Thailand yielded the first complete molars of Stegolophodon ever found in this country. A complete M 3 from Mae Moh (Middle Miocene) and a partial mandible with M 2 –M 3 from Na Sai (Early Miocene), are described with new data on the evolution of the genus in South East Asia. A new species is described in the Early Miocene locality of Na Sai, being the earliest known species of Stegolophodon . The differentiation of tetralophodont forms is much older than was previously thought.

The proboscidean fauna of the middle Miocene of Thailand consists of five taxa, including four elephantoids and one deinothere. The Thai association is dominated by the genera Stegolophodon and Gomphotherium. Stegolophodon is represented by S. nasaiensis and S. praelatidens. The latter species, considered invalid and possibly conspecific with S. latidens, is re-erected. Its phylogenetic relationships are discussed. The Thai Gomphotherium matches with G. browni from the middle Miocene of Indo-Pakistan. However, the open nomenclature is employed for the Thai material because it differs from G. browni in terms of curvature of the upper tusk. Intraspecific molar size variation observed in G. cf. browni and Stegolophodon praelatidens is attributed to sexual dimorphism. The Thai proboscidean asssemblage is mainly endemic compared with other contemporaneous Asian faunas although the recognition of Gomphotherium cf. browni denotes faunal affinities with Pakistan. The biostratigraphical implications of the taxa are examined in a regional context. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155, 703–721.

The Manchar Formation, a middle and upper Miocene fluvial sequence of sandstones, silts, and conglomerates, is exposed in a narrow north–south belt in the Lower Indus Basin of Sind Province, Pakistan. The formation, as measured in geological sections near Lake Manchar, can be divided into three parts differing in the proportions of the sandstones and silts. The contact with the underlying marine Gaj Formation is gradational; when the base of the Manchar Formation is taken as the lowest thick sandstone of fluvial origin, it lies above the highest marine or estuarine beds. Fossil localities cluster into three stratigraphie groups which correspond to the three horizons previously recognized. New additions to the Manchar faunas include a large hominoid and another small primate, two creodonts, three amphicyonids, a shovel-tusked amebelodontine, a chalicothere, species of Orycteropus, Zygolophodon, Stegolophodon, and Brachyodus, a species comparable to Tetraconodon minor, two small species of Dorcathe...