A new species Theronia qaidamensis sp. nov. (Ichneumonidae, Pimplinae) is described from the Oligocene Shangganchaigou Formation of the northwestern Qaidam Basin (Huatugou area), northeast of the Tibetan Plateau (TP). The new species represents the first report of the Ichneumonidae from the Qaidam Basin, which reveals an insect linkage between the Qaidam Basin and Europe. In addition, the study of associated fossils from the Shangganchaigou Formation shows that the palaeoenvironment of the northwestern Qaidam Basin during the Oligocene was warm and moist, which provided suitable living conditions for the current fossil.
ABSTRACTIt is indisputable that large parts of the Cretaceous can be considered as a particular 'high-fire' interval, supported by numerous published records of palaeo-wildfires during this period. The presence of charcoal is widely accepted as direct evidence of palaeo-wildfires. In this study, macroscopic charcoal from the Early Cretaceous Chijinpu Formation in the Zhongkouzi Basin, Beishan area, northwestern China, is reported and described. These charcoal fragments serve as reliable evidence of palaeo-wildfires that occurred in northwestern China during the Early Cretaceous. Based on anatomical characteristics, the charcoal remains were identified to gymnosperms, most probably conifers, which is in accordance with previous palaeobotanical records from the Chijinpu Formation. It is reasonable to infer that wildfire played a significant role in the ecosystems of this region. We consider that the forests with rich conifers and the dry climatic conditions, were probably conducive to the ignition and spread of wildfires. Conifers, in particular, could have played a significant role in this process by providing abundance and flammable fuel sources for the fire. The present study contributes new evidence to our knowledge of the Early Cretaceous wildfires and enriches our knowledge of the vegetation and environmental conditions in the study area.KEYWORDS: Charcoalpalaeo-wildfiregymnospermsEarly CretaceousChijinpu Formationnorthwestern China AcknowledgmentsWe are thankful to two anonymous reviewers for their valuable comments and suggestions. We are thankful to Prof. Yan Defei, Mr Hui Jianguo (Lanzhou University) and Mr Zhu Yanbin (Nanjing Institute of Geology and paleontology, CAS) for their valuable discussion and help.Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingThis work was supported by the Second Tibetan Plateau Scientific Expedition and Research Program (2019QZKK0704), the National Natural Science Foundation of China (41972010), and the State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology, CAS) (213115).
Trapa L. (Lythraceae J. ST.-HIL) is a genus of annual free-floating plant, widely distributed in the Northern Hemisphere. The Qaidam Basin is regarded as an ideal region to understand the Cenozoic palaeoclimatic and palaeobiological evolution of the northern Tibetan Plateau. A few records of Trapa have been previously mentioned from the Cenozoic deposits of the Qaidam Basin, northern Tibetan Plateau. Here, we describe some fossil fruits of Trapa from the late Miocene Shangyoushashan Formation of southeastern Qaidam Basin (Tuosu Lake area), which were identified as Trapa qaidamensis sp. nov. based on their morphology. Extant species of Trapa usually live in the environments with mean temperature of warmest quarter (MTWQ) ranging from 14.9°C to 30.9°C, as well as mean temperature of warmest month (MTWM) ranging from 19.6°C to 37.3°C in the living areas of Trapa. Compared with MTWQ 16.5°C and MTWM 17.5°C in current fossil locality, the present fossil site was warmer during the Miocene than in the present day.urn:lsid:zoobank.org:act:9F7DAD1B-DA2D-4734-BE27-99276F57DD2A
Fossils are critical for understanding the environmental changes and uplift history of the Tibetan Plateau during the Cenozoic. As the largest inland basin located at the northeastern plateau, Qaidam Basin has been regarded as the key region to understand the climatic changes in the plateau during the Cenozoic. Herein, fossil legumes from the Oligocene Shangganchaigou Formation in northwestern Qaidam Basin have been reported and are assigned to Desmanthus cf. virgatus (L.) Willd. based on morphological comparison. Current materials represent the first megafossil record of this genus in the world. The living analogues of current fossils now live in regions with mean annual temperature values (MAT) ranging from 13.4 to 29.1°C and mean annual precipitation values (MAP) ranging from 36 to 2874 mm while the MAT and MAP of current northwestern Qaidam Basin is −1.03°C and 60.5 mm, respectively, and indicate that the Oligocene Qaidam was much warmer than today. We calculate that current fossils could grow no higher than 2492 m considering the climatic condition of the Oligocene Qaidam. The difference between estimated and modern elevation of the fossil site suggests that the elevation of the research area has increased by at least ≈1000 m since the Oligocene.
The Qaidam Basin, lying in the north-eastern Tibetan Plateau, China, is key to understanding the Cenozoic climatic and biological changes that have occurred on the plateau; however, information from a palaeontological perspective on this Palaeogene basin is scant. Recently, fossil cyprinids were found in the middle portion of the Shangganchaigou Formation (= Upper Ganchaigou Formation; Oligocene) in the north-western Qaidam Basin. These share many osteological characters with barbines and ‘morphologically primitive clade schizothoracines’ (= primitive schizothoracines; i.e. Schizothorax and Aspiorhynchus), and they closely resemble the latter in the size and shape of the scales: body scales are small and oval; the number of lateral line scales exceeds 100; and the long-oval scales from the pre-anal region are very similar to the ‘anal scales’, which are unique to schizothoracines. Compared with another fossil fish, Paleoschizothorax qaidamensis, from the same formation, the major differences are: (1) the posterior part of the entopterygoid in the new material is normal and not expanded while that of P. qaidamensis is obviously expanded; and (2) the premaxilla process of maxilla is well developed in P. qaidamensis but weak in the new specimens. Therefore, they are described as a new species of the fossil genus Paleoschizothorax (subfamily Schizothoracinae): Paleoschizothorax diluculum sp. nov. A phylogenetic analysis, which included 13 extant genera and three fossil forms of barbines and schizothoracines and 70 morphological characters, also supports the close relationship between P. diluculum and primitive schizothoracines. A preliminary correlation analysis suggests that the degree of reduction of body scale size is negatively correlated with habitat mean temperatures among most Chinese cyprinids. Moreover, we speculate that the ‘primitive schizothoracines’ likely originated in the north-eastern–central Tibetan Plateau based on the fossil records and molecular phylogeny of the extant taxa. http://zoobank.org/urn:lsid:zoobank.org:pub:C461C7C0-9BAB-44DD-8DEE-0B5BB03D6479
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)