Fossils of the ursid Indarctos from Withlacoochee River 4A of Florida (late early Hemphillian North American Land Mammal Age, Hh2, ~ 7.5–6.5 Ma) represent the best sample of this genus in North America, including both craniodental and postcranial specimens, yet only the skull has been described. In this study, we describe the other material of this bear from the same locality and review the records of Indarctos in North America. Indarctos from Withlacoochee River 4A has dental characters in accordance with those of typical Indarctos oregonensis, but has distinctly more slender postcranial bones. Indarctos from other localities of North America contains two morphs with regards to postcranial robustness, but lacks a clear geographic pattern. Indarctos from Withlacoochee River 4A shares traits with the Old World Indarctos zdanskyi and may be its descendant in the New World. The machairodont from Withlacoochee River 4A shows typical characters (e.g., presence of distinct P4 preparastyle and mandibular flange) that allow referral to Amphimachairodus rather than to Nimravides. Its morphology also shows a stronger affinity of this population to the Old World Amphimachairodus horribilis rather than to Hh3 Amphimachairodus coloradensis. Previously, most North American records of Amphimachairodus were late Hemphillian (Hh3–4, ~ 6.5–4.5 Ma), when it co-occurred with a different ursid, “Agriotherium.” The Withlacoochee River 4A specimens provide evidence that Amphimachairodus dispersed from Asia during the Hh2. The special morphology of Indarctos and the presence of Amphimachairodus in a Hh2 fauna suggest that the environment had begun to change before the significant fauna turnover between the early and late Hemphillian.
QIGAO Jiangzuo
The cranial appendage (headgear) is an iconic structure of modern ruminants, and four of the five extant pecoran families display morphological and physiological specialties. They probably share one origin from the same genetic basis, whereas the evolution of the cranial appendages is still debatable, especially in consideration of fossil taxa lacking headgear. Amphimoschus is an enigmatic pecoran that comprises no more than two species, mainly known from the late early/early middle Miocene of Western and Central Europe and considered not to possess any cranial appendages. Here, we present Amphimoschus xishuiensis sp. nov., discovered in the Tabenbuluk area, Gansu Province, China. The new species reveals the first evidence of cranial ornamentations in the genus, including a supraorbital bump, an antorbital protuberance and frontal thickening. In our phylogenetic analysis the genus was inferred as a basal member of the Bovoidea, and thus the cranial ornamentations of A. xishuiensis might provide insight into the early evolution of cranial appendages in Bovoidea. They could be interpreted as weapons to defend territories in intense intraspecific or interspecific competition during the late early Miocene.
DENG Tao
Owing to the scarcity of records, the Asian evolution and migration of Diaceratherium, a large extinct genus of rhinoceros of the Teleoceratini, remain unclear. The skeleton described herein, from the early Miocene Shanwang Basin in China, is identified as Diaceratherium shanwangense, a species originally defined based on upper cheek teeth. This skeleton features a large body, short horn-bearing nasal bones, moderately retracted nasal notch at the P3 level, and the metapodials that are less massive than those in other previously identified species of Diaceratherium. Mammalian fossils reported from the Oligocene–Miocene transition of the Old World, such as Dorcatherium and Amphicyon, have indicated a migration route between Europe and Eastern Asia via Southern and South-eastern Asia, namely along the southern margins of the Tibetan Plateau. However, the fossil remains of Diaceratherium reported in this study were discovered in eastern China, which represents the second accurate record of the genus in Asia (together with its presence in Kazakhstan). Consequently, given the temporal range and geological distribution of Diaceratherium, we propose that the expansion of this genus to the eastern part of the continent occurred via a route following the northern margins of the Tibetan Plateau, which if verified, represents an alternative expansion route differing from the established routes of other mammals.
DENG Tao
The water vapor isotopes transported by different atmospheric circulation systems are different, and the precipitation on the Qinghai Tibet Plateau is affected by monsoon and westerly circulation, which is very sensitive to climate and environmental change. Hydrogen isotopes of wax in lake sediments provide a means to restore past precipitation information. The stable hydrogen isotope records of sediments from different lakes (Qinghai Lake, linggecuo lake and Bangong Lake) in the East and west of the Qinghai Tibet Plateau provided by the author reconstruct the isotopic changes of precipitation in the East and west of the Qinghai Tibet Plateau in the past 20000 years, and study the effects of summer monsoon and westerly jet on water vapor in the Qinghai Tibet Plateau since the late Pleistocene, It also provides important basic data for reconstructing the paleoclimate and environmental changes of the Qinghai Tibet Plateau in the past.
HOU Juzhi
XRF data can quickly, nondestructive and high-resolution obtain the relative abundance of constant and trace geochemistry, which can be used to reconstruct the environmental change. This data includes the XRF multi-element data of Daze Co and Jiang Co and the age depth data of Lake cores, which can be used to reconstruct the climate and environmental changes in the East and west of the Qinghai Tibet Plateau in the past 20000 years. In Daze Co and Jiang Co lakes, Ti, K, Fe, Si and other elements show the same change trend. Through multi index comparative analysis, it is considered that Ti and other rock forming elements are mainly affected by the inner diameter flow conditions of the basin and can be used to reconstruct the changes of hydrological conditions in the basin in recent 20000 years.
HOU Juzhi
1) The data include the temperature records reconstructed by using the core depth, age and biomarker gdgts of Bangong Lake to reconstruct the annual average temperature change of Bangong Lake Basin in the west of Qinghai Tibet Plateau since the last deglaciation. At present, most paleoclimate records on the plateau are qualitative and semi quantitative, and the quantitative records are very limited, which restricts the in-depth understanding of the mechanism of climate change on the plateau. Bangongcuo, the largest lake in the west of Qinghai Tibet Plateau, was selected as the study area, and the average annual temperature change in this area since 16 ka BP was reconstructed by using biomarker indexes. 2) The record was reconstructed using gdgts of lake sediments. 3) The data are detailed and reliable. 4) This study not only provides data for understanding the past climate change in the western Qinghai Tibet Plateau, but also provides a basis for discussing the plateau climate change mechanism and verifying the reliability of regional climate model.
HOU Juzhi, WANG Mingda
The data include the carbonate content, carbon isotope and oxygen isotope analysis results of inorganic carbonates of 79 samples from 850 m natural section of the middle late Eocene in the salkuli basin. The carbon and oxygen isotopes of carbonate in the sediments record the hydrological and vegetation information in the geological history, which is one of the main indicators of paleoenvironmental tracer research. After grinding and sieving, the carbon and oxygen isotope analysis is completed by the sample processing unit (carbonate device) and MAT252 isotope mass spectrometry online automatic online system. The analytical accuracy of the sample is: carbon isotope is better than ± 0.06 ‰, and oxygen isotope is better than ± 0.08 ‰. Through the analysis of carbon and oxygen isotope data of solkuli section, the evolution history of arid environment since Eocene can be reconstructed, and the paleoclimate effect of the Tibetan Plateau uplift and global climate change can be discussed.
SUN Jimin
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