The Tertiary deposits of the Yongdeng section, the Lanzhou Basin were studied by means of magnetostrati-graphy. The magnetostratigraphic sequences from Paleocene to Miocene were established, and the time scale for the...The Tertiary deposits of the Yongdeng section, the Lanzhou Basin were studied by means of magnetostrati-graphy. The magnetostratigraphic sequences from Paleocene to Miocene were established, and the time scale for the corresponding stratigraphy and mammalian faunas was also established by referring to their correlation to the GPTS of BKSA95 (The geomagnetic polarity time scale which was thoroughly revised and updated by Berggreen et al. in 1995). In the end the paleoenvironmental records and their relationship with the uplifting of the Tibetan Plateau were discussed. The results are as follows. The top boundary of the Xiliugou Formation is dated to be 51 Ma, i.e. Eocene. TheYehucheng Formation covers the time span of 51-31.5 Ma, i.e. from late Early Eocene to early Early Oligocene. The Xianshuihe Formation covers the time span of 31.5-15 Ma, i.e. from Early Oligocene to Middle Miocene. The lower member of the Xianshuihe Formation spans from 31.5 to 20.0 Ma, i.e. from Early Oligocene to early Early展开更多
The distal extremity of a rhinocerotid humerus from the upper part of the Dingqing Formation at the Lunbori locality in Baingoin County,northern Tibet,is the first mammalian fossil found in Cenozoic deposits of the Lu...The distal extremity of a rhinocerotid humerus from the upper part of the Dingqing Formation at the Lunbori locality in Baingoin County,northern Tibet,is the first mammalian fossil found in Cenozoic deposits of the Lunpola Basin.The medial condyle of the distal trochlea of the humerus specimen from Lunbori gradually contracts from medially to laterally.The margin of the medial surface of the medial condyle is not prominent,the well-developed medial epicondyle strongly extends posteriorly,and is divided from the articular facet of the medial condyle by a groove;all of which are characteristic for the Rhinocerotidae.The medial condyle is wide at the bottom and narrow at the top.The medial collateral ligament fossa is relatively shallow,and the medial collateral ligament tubercle is very weak.The medial part of the upper margin of the medial condyle smoothly connects to the bony surface above,but there is no clear boundary between them.All of these characteristics are identical with those of Plesiaceratherium.These comparisons imply that the Lunbori specimen is closest to Plesiaceratherium gracile in the Shanwang Fauna from Linqu,Shandong Province,in size and morphology.Thus,its age is suggested to be the late Early Miocene(Shanwangian Age),about 18-16 Ma.Discovery of the rhinocerotid fossil suggests that the upper part of the Dingqing Formation deposited in the Neogene.While adjusting to paleo-temperatures of the Early Miocene,a paleo-ecosystem reconstruction indicates that the paleo-elevation was close to 3000 m in the Lunpola Basin during this time.展开更多
We report a fossil specimen referable to Sinomastodontinae gen. et sp. indet. from the Neogene strata at Yanghecun locality, Xihe County, Gansu Province, China. The specimen is characterized by a brevirostrine mandibl...We report a fossil specimen referable to Sinomastodontinae gen. et sp. indet. from the Neogene strata at Yanghecun locality, Xihe County, Gansu Province, China. The specimen is characterized by a brevirostrine mandible, complete pretrite trefoils, and relatively simple posttrite half lophids, showing typical features of Sinomastodon. It differs from the other known species of Sinomastodon by the following features: relatively short and wide m3 due to fewer lophid numbers, less inflated pretrite accessory central conules, poorly developed secondary trefoils and cementum, and relatively strong cingulid. All of these features indicate a bias towards pleisiomorphies of Sinomastodon, implying that this specimen is more ancestral than any known species of Sinomastodon. The symphysis of the new specimen is relatively long, which differs from the typical brevirostrine Sinomastodon, and thus we consider it a gen. et sp. indet. in the Subfamily Sinomastodontinae. In addition, the horizon in which the present specimen was found probably represents the Upper Miocene because it is lower than Pliocene strata yielding Hipparion(Proboscidipparon) pater. Generally, Sinomastodon is considered to have migrated from North America at about the time of the Miocene/Pliocene boundary, and to have been derived from a certain clade of American gomphotheres. However, the discovery of the Yanghecun specimen verifies that Sinomastodon lived in East Asia during the Late Miocene, and probably derived from Old World gomphotheres(e.g., G. wimani). The similarity between the members of the Subfamilies Sinomastodontinae and those of Cuvieroniinae is suggested to have been the result of parallel evolution.展开更多
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 49472083, 49572133 and 49972004) and the Institute Fund of ETH, Switzerland.
文摘The Tertiary deposits of the Yongdeng section, the Lanzhou Basin were studied by means of magnetostrati-graphy. The magnetostratigraphic sequences from Paleocene to Miocene were established, and the time scale for the corresponding stratigraphy and mammalian faunas was also established by referring to their correlation to the GPTS of BKSA95 (The geomagnetic polarity time scale which was thoroughly revised and updated by Berggreen et al. in 1995). In the end the paleoenvironmental records and their relationship with the uplifting of the Tibetan Plateau were discussed. The results are as follows. The top boundary of the Xiliugou Formation is dated to be 51 Ma, i.e. Eocene. TheYehucheng Formation covers the time span of 51-31.5 Ma, i.e. from late Early Eocene to early Early Oligocene. The Xianshuihe Formation covers the time span of 31.5-15 Ma, i.e. from Early Oligocene to Middle Miocene. The lower member of the Xianshuihe Formation spans from 31.5 to 20.0 Ma, i.e. from Early Oligocene to early Early
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-Q09)the National Basic Research Program of China (2012CB821906)the National Natural Science Foundation of China (40730210)
文摘The distal extremity of a rhinocerotid humerus from the upper part of the Dingqing Formation at the Lunbori locality in Baingoin County,northern Tibet,is the first mammalian fossil found in Cenozoic deposits of the Lunpola Basin.The medial condyle of the distal trochlea of the humerus specimen from Lunbori gradually contracts from medially to laterally.The margin of the medial surface of the medial condyle is not prominent,the well-developed medial epicondyle strongly extends posteriorly,and is divided from the articular facet of the medial condyle by a groove;all of which are characteristic for the Rhinocerotidae.The medial condyle is wide at the bottom and narrow at the top.The medial collateral ligament fossa is relatively shallow,and the medial collateral ligament tubercle is very weak.The medial part of the upper margin of the medial condyle smoothly connects to the bony surface above,but there is no clear boundary between them.All of these characteristics are identical with those of Plesiaceratherium.These comparisons imply that the Lunbori specimen is closest to Plesiaceratherium gracile in the Shanwang Fauna from Linqu,Shandong Province,in size and morphology.Thus,its age is suggested to be the late Early Miocene(Shanwangian Age),about 18-16 Ma.Discovery of the rhinocerotid fossil suggests that the upper part of the Dingqing Formation deposited in the Neogene.While adjusting to paleo-temperatures of the Early Miocene,a paleo-ecosystem reconstruction indicates that the paleo-elevation was close to 3000 m in the Lunpola Basin during this time.
基金supported by Chinese Academy of Sciences(Grant No.XDB03020104)National Basic Research Program of China(GrantNo.2012CB821900)+1 种基金National Natural Science Foundation of China(Grant Nos.41372001,41002010,40730210)the Important Research Plan of IVPP
文摘We report a fossil specimen referable to Sinomastodontinae gen. et sp. indet. from the Neogene strata at Yanghecun locality, Xihe County, Gansu Province, China. The specimen is characterized by a brevirostrine mandible, complete pretrite trefoils, and relatively simple posttrite half lophids, showing typical features of Sinomastodon. It differs from the other known species of Sinomastodon by the following features: relatively short and wide m3 due to fewer lophid numbers, less inflated pretrite accessory central conules, poorly developed secondary trefoils and cementum, and relatively strong cingulid. All of these features indicate a bias towards pleisiomorphies of Sinomastodon, implying that this specimen is more ancestral than any known species of Sinomastodon. The symphysis of the new specimen is relatively long, which differs from the typical brevirostrine Sinomastodon, and thus we consider it a gen. et sp. indet. in the Subfamily Sinomastodontinae. In addition, the horizon in which the present specimen was found probably represents the Upper Miocene because it is lower than Pliocene strata yielding Hipparion(Proboscidipparon) pater. Generally, Sinomastodon is considered to have migrated from North America at about the time of the Miocene/Pliocene boundary, and to have been derived from a certain clade of American gomphotheres. However, the discovery of the Yanghecun specimen verifies that Sinomastodon lived in East Asia during the Late Miocene, and probably derived from Old World gomphotheres(e.g., G. wimani). The similarity between the members of the Subfamilies Sinomastodontinae and those of Cuvieroniinae is suggested to have been the result of parallel evolution.
