您当前的位置:首页 > 论文浏览


1. chinaXiv:201804.01249 [pdf]

Negligible effect of tooth reduction on body mass in Mesozoic birds

ZHOU Ya-Chun; ZHANG Fu-Cheng; Corwin SULLIVAN
分类: 地球科学 >> 地质学

Tooth reduction and loss was an important evolutionary process in Mesozoic birds. Analysis of evolutionary trends in the total mass of the dentition, a function of tooth size and tooth number, has the potential to shed light on the evolutionary pattern of tooth reduction and loss, and on the causes of this pattern. Because modern birds lack teeth, however, they cannot provide the basis for a model that would allow estimation of tooth masses in their Mesozoic counterparts. We selected the teeth of crocodilians as analogues of those in Mesozoic birds because the former are the closest living relatives of the latter, and the two groups are similar in tooth morphology, tooth implantation, and tooth replacement pattern. To estimate tooth masses in Mesozoic birds, we formulated four regression equations relating tooth mass to various linear dimensions, which were measured in 31 intact isolated teeth from eight individual crocodiles (Crocodylus siamensis). The results for Mesozoic birds show that dental mass as a proportion of body mass was negligible, at least from the perspective of flight performance, suggesting that selection pressure favoring body mass reduction was probably not the primary driver of tooth reduction or loss. Variations in dental mass among Mesozoic birds may reflect the different foods they ate, and the different types of feeding behavior they displayed.

提交时间: 2018-04-04 来自合作期刊:《古脊椎动物学报》 点击量206下载量95 评论 0

2. chinaXiv:201804.01250 [pdf]

A new species of Kubanochoerus (Suidae, Artiodactyla) from the Linxia Basin, Gansu Province, China

HOU Su-Kuan; DENG Tao
分类: 地球科学 >> 地质学

A new specimen of kubanochoeres has been discovered from the Maida locality, Linxia Basin, Gansu Province, China, and a new species, Kubanochoerus parvus sp. nov., has been created based on the unique partially broken cranium. The new species has a relatively small body size similar to K. massai and K. minheensis. The new species, which possesses relatively wide cheek teeth that resemble those of K. massai and many derived characters that are similar to K. gigas, may represent a separate lineage of the Eurasian kubanochoeres. The horizon of the Maida locality is speculated to be the upper Hujialiang Formation or lower Liushu Formation, and the new species is possibly the youngest known kubanochoere. Based on the comparison of the known kubanochoere, Libycochoerus is suggested to be a synonym of Kubanochoerus, while K. robustus and K. lantienensis are synonyms of K. gigas. There is not sufficient evidence to support the subdivision of K. gigas at the subspecies level. Kubanochoerus gigas is speculated to have derived from more primitive forms that existed earlier than K. massai, and the new species may be derived from K. massai or other earlier forms. Kubanochoerus minheensis, which bears a relatively small body size and rudimentary sub-lophodont dentition, is suggested to be another separate lineage of the Eurasian kubanochoeres.

提交时间: 2018-04-04 来自合作期刊:《古脊椎动物学报》 点击量239下载量117 评论 0

3. chinaXiv:201804.01251 [pdf]

Fossil gibbons (Mammalia, Hylobatidae) from the Pleistocene of Chongzuo, Guangxi Zhuang Autonomous Region, China

ZHANG Ying-Qi; JIN Chang-Zhu; WANG Yuan; Alejandra ORTIZ; HE Kai; Terry HARRISON
分类: 地球科学 >> 地质学

Recent fieldwork at Pleistocene cave sites in the Chongzuo area in Guangxi Zhuang Autonomous Region has yielded 33 isolated teeth of fossil hylobatids. Comparisons indicate that the teeth can all be referred to a single species of Nomascus, but the material is insufficient to assign it to a particular species. The molars are slightly larger on average than those of extant species of Nomascus, but unlike contemporary great apes from the Pleistocene of southern China, the hylobatids do not seem to have undergone a change in dental size through time. Nomascus is not present in the Chongzuo area today, but historical records indicate that the genus may have been widely distributed across southern China in the recent past.

提交时间: 2018-04-04 来自合作期刊:《古脊椎动物学报》 点击量228下载量97 评论 0

4. chinaXiv:201803.00011 [pdf]

New material of the Late Miocene Moschus (Artiodactyla, Mammalia) from Huade, Nei Mongol, North China

DONG Wei; LIU Wen-Hui; ZHANG Li-Min; BAI Wei-Peng; CAI Bao-Quan
分类: 地球科学 >> 地质学

Moschus grandaevus was firstly uncovered from the Late Miocene deposits at Ertemte, Olan Chorea, Harr Obo and Hua Ba in or around Huade County in the middle part of Nei Mongol and was described by Schlosser in 1924. The excavations by Sino-Soviet Joint Paleontological Team in 1959 and recent excavations since 2013 at Tuchengzi (Tuchetse), another locality at Huade, accumulated many specimens of the musk deer. The morphology and metric studies show that the musk deer specimens from Tuchengzi are the same as those described by Schlosser and can be included into the same species. M. grandaevus ranges from Siberia of Russia to North China, and likely to southern China, in the Late Miocene and Pliocene. The appearance of such folivorous musk deer in the Late Miocene deposits at Tuchengzi indicates that there were forests there during that period. The cladistic analyses show that the fossil species of Moschus are closely related to each other and can be grouped together as Moschini or Moschinae. Micromeryx is closer to Moschus and Cervidae, but the relationship between Micromeryx and Moschus is more complicated than previously considered; nonetheless Hispanomeryx is closer to Bovidae. Schlosser (1924)记述了最初发现于内蒙古化德境内或附近的二登图、敖兰卓蕾、哈尔敖包及华坝的古麝(Moschus grandaevus)。1959年中苏古生物考察队在化德的另一个地点土城子采集到不少古麝化石。2013年以来作者在土城子进行的野外发掘积累了更多的古麝化石标本。土城子标本在形态和测量数据方面和二登图等地点的古麝非常接近,可以归入同一种。根据现有资料归纳,古麝的地理分布范围自俄罗斯的西伯利亚到华北,很可能延伸到华南;其地质时代分布范围为晚中新世–上新世。食叶型古麝在土城子晚中新世地层中的出现说明当时土城子一带有森林环境。支序分析显示麝属(Moschus)化石种相互之间的系统关系非常近,可以归并为麝族(Moschini)或麝亚科(Moschinae); Micromeryx更接近麝属和鹿科,它与麝属之间的关系比以前认为的复杂,而Hispanomeryx更接近牛科。

提交时间: 2018-03-02 来自合作期刊:《古脊椎动物学报》 点击量1684下载量239 评论 0

5. chinaXiv:201802.00746 [pdf]

Reappraisal of Endotherium niinomii Shikama, 1947, a eutherian mammal from the Lower Cretaceous Fuxin Formation, Fuxin-Jinzhou Basin, Liaoning, China

WANG Yuan-Qing; KUSUHASHI Nao; JIN Xun; LI Chuan-Kui; SETOGUCHI Takeshi; GAO Chun-Ling; LIU Jin-Yuan
分类: 地球科学 >> 地质学

Reinvestigation of the Early Cretaceous eutherian mammal Endotherium niinomii Shikama, 1947, based on the impressions of the type specimen, casts made from the impressions, and the original description, indicates that E. niinomii is characterized by the following characters: decrease in size from the m1 to the m3; a moderate height difference between the trigonid and talonid of lower molars; blunt lower molar cusps; the protoconid being the largest among the trigonid cusps; the paraconid being as tall as the metaconid; the p3 not being obviously reduced; and possible possession of five lower premolars. These characteristics clearly distinguish E. niinomii from other known Cretaceous eutherians, and support its taxonomic identity as a valid taxon.

提交时间: 2018-02-26 来自合作期刊:《古脊椎动物学报》 点击量715下载量214 评论 0

6. chinaXiv:201801.00584 [pdf]

Postcranial morphology of Middle Eocene deperetellid Teleolophus (Perissodactyla, Tapiroidea) from Shara Murun region of the Erlian Basin, Nei Mongol, China

BAI Bin; WANG Yuan-Qing; MENG Jin
分类: 地球科学 >> 地质学

Deperetellidae are a group of common, endemic Asian Middle Eocene tapiroids. Although five genera within the family have been named, most of them were represented by fragmentary maxillae and mandibles except for some skeletal material of Deperetella. Based exclusively on dental characters, different authors have proposed affinities of deperetellids with, for instance, helaletid Colodon, lophialetids, or rhodopagids. Here we described the partial postcranial skeleton of Teleolophus medius? recently discovered at Wulanhuxiu (=Ulan Shireh) of the Erlian Basin, China, and compared the postcranial skeletons of Teleolophus with those of Lophialetes, Deperetella, Heptodon, Helaletes, and Colodon. The postcranial skeleton of Teleolophus shares many similarities with that of Deperetella especially in having elongated and slender limbs, a relatively long, narrow lunar with a slightly concave medial border of the radial facet, a magnum with an anteriorly situated hump and a deeply excavated Mc IV facet, Mc II not elevated above Mc III, a slightly asymmetric trochlea of the femur, a fibula highly reduced or even fused with a tibia, Mt III contacting the cuboid, Mt II in contact with ectocuneiform only on the posterior end, and the manus and pes with functional tridactyls. These similarities support the close relationship between Teleolophus and Deperetella. We interpreted some similarities of postcrania between Teleolophus and Lophialetes as a result of parallel evolution, due to their cursorial adaptations. Colodon is more similar to Heptodon than to Teleolophus in the postcranial features, suggesting a close relationship between Colodon and Heptodon. Whether or not Helaletidae and Deperetellidae are closely related await further investigation. Both morphological characters and ternary diagram indicate that Teleolophus adapted to fast running, as its contemporary Lophialetes.

提交时间: 2018-01-25 来自合作期刊:《古脊椎动物学报》 点击量984下载量448 评论 0

7. chinaXiv:201801.00509 [pdf]

The first Stalicoolithus shifengensis discovered in a clutch from the Sanshui Basin, Guangdong Province

ZHU Xu-Feng; FANG Kai-Yong; WANG Qiang; LU Xiao-Hong; WU Wei-Qiang; DU Yan-Li; HUANG Zhi-Qing; WANG Xiao-Lin
分类: 地球科学 >> 地质学

The first clutch of Stalicoolithus shifengensis is described here. This incomplete dinosaur egg clutch in which three nearly complete eggs and two egg prints were preserved was discovered in the red deposits of the Sanshui Formation at a construction site near the sluice of North Village, Dali Town, Nanhai District, Foshan City, Guangdong Province, China. The eggs in the clutch are stacked with various ranges. Based on the characteristics of the eggshell, these eggs can be assigned to S. shifengensis. The discovery of S. shifengensis in the Sanshui Formation complements the clutch information about the oospecies as well as expands its paleogeographic distribution, and sets the foundation for discussing the diversity of dinosaur eggs in the Sanshui Basin.

提交时间: 2018-01-23 来自合作期刊:《古脊椎动物学报》 点击量998下载量303 评论 0

8. chinaXiv:201801.00114 [pdf]


孙威; 毛凌潇
分类: 地球科学 >> 地理学

[目的/意义] 中国是世界遗产最多的国家之一,传承保护好这些珍贵的历史文化遗产是中国人民,也是世界人民的共同责任,但是如何处理好文化遗产保护利用与城乡改造开发的关系却是一个重大的现实问题。[方法/过程] 采用实地调研、案例分析、对比研究等方法,分析了美国黑石河峡谷遗产廊道、日本纪伊山脉胜地的基本概况,总结了上述两个案例的成功经验,提出了对北京西山文化带的建设启示。[结果/结论] 研究表明,国际上山岳型遗产地保护发展有不少成功经验,可以概括为重视文化遗产保护,自然景观与人文景观相协调;因势利导发展旅游业,促进文化遗产保护与利用相结合;完善规划管理体系,政府管理与民众意愿相统一;成立专门机构,促进国家、地方、民众相联合。这启示北京应进一步凝练西山文化带的文化特色和内涵、切实保护和利用好自然和文化资源、成立专门机构进行统一管理、加强规划引导和功能定位。

提交时间: 2018-01-11 来自合作期刊:《智库理论与实践》 点击量2084下载量385 评论 0

9. chinaXiv:201801.00122 [pdf]


分类: 地球科学 >> 地理学

[目的/意义] 针对新世纪我国土壤污染凸显的严峻形势,探索能有效改善土壤质量、保护土壤环境和安全利用土地资源的战略机制,对保障农产品质量安全和公众健康、实现土地可持续利用和推动生态文明建设具有重要的现实意义和深远的战略影响。[方法/过程] 本文系统分析了我国土壤污染防治过程中面临的主要问题及挑战,并从土壤环境保护和土地安全利用的宏观视角定位土壤污染防治的关键举措。[结果/结论] 研究发现,我国土壤污染防治工作以农田和工业用地为治理重点,虽已在多方面取得重大进展,但仍存在以下主要问题:(1)针对农田污染,存在污染物空间异质性强、土壤污染与农产品超标差异大、土壤污染源头管控不到位和农田安全利用困难等问题;(2)针对工业污染地块,存在污染防治的政策法规体系不完善、技术能力建设滞后、片面强调工程修复和修复模式不持续等问题。为保护国家土壤生态安全,促进土地安全利用战略规划,应加快完善土壤污染防治顶层设计,系统开展源头治理、精准治理与综合治理,坚持“可持续修复、适度修复和绿色修复”原则,加强产业链中各利益方的密切合作,开拓多元稳定的土壤修复筹融资渠道,建立土壤环境质量预警机制。

提交时间: 2018-01-11 来自合作期刊:《智库理论与实践》 点击量1811下载量309 评论 0

10. chinaXiv:201801.00103 [pdf]

New materials of Choerolophodon (Proboscidea) from Dhok Pathan Formation of Siwaliks, Pakistan

Sayyed Ghyour ABBAS; Muhammad Akbar KHAN; Muhammad Adeeb BABAR; Muhammad HANIF; Muhammad AKHTAR
分类: 地球科学 >> 地质学

Choerolophodon corrugatus is the only species of the genus Choerolophodon found in the Siwalik Group. Its first appearance is in the Kamlial Formation (Middle Miocene) of the Lower Siwalik Subgroup and it is most abundant in the Dhok Pathan Formation of the Middle Siwalik Subgroup (Late Miocene to Early Pliocene). New remains of Choerolophodon corrugatus have been recovered from the Dhok Pathan type locality and its adjacent areas. The specimens include tusks, mandible and maxillary fragments, and deciduous premolars and permanent molars. The Siwalik species shows great affinity with the European species Ch. pentelici in dentition and differs in the cranial and mandibular characteristics.

提交时间: 2018-01-09 来自合作期刊:《古脊椎动物学报》 点击量1160下载量350 评论 0

12345678910  尾页  转到  [42 页/ 420 条记录]