中国晚中新世陆相哺乳动物群序列:陕西蓝田的新证据(英文)

自 2 0世纪 60年代 ,陕西蓝田地区就以连续的晚新生代地层及丰富的哺乳动物化石而成为研究中国晚新生代哺乳动物与地层划分对比的经典地区之一。李传夔等 ( 1 984)根据灞河组发现的哺乳动物化石建立了灞河期 ,并与欧洲的Vallesian期对比。邱占祥等( 1 990 ,1 995)认为化石证据不充分 ,而将其与保德期合并。近年来 ,黄土高原三趾马红粘土大量的年代学资料表明 ,红粘土沉积最早可能开始于约 8Ma前。因此 ,狭义的保德期可能只代表了晚中新世晚期 ,晚中新世哺乳动物分期的再划分问题又重新被提出。自 1 997年以来 ,我们课题组在蓝田地区共发现 52个化石地点 ,其中的 2 6个含有哺乳动物化石 ,大哺乳动物化石标本共计 1 666件。经过详细野外地层测量 ,绘制了综合地层剖面 ,并将主要含哺乳动物化石的地点对比标定到综合地层剖面上。经过对各门类化石的初步研究 ,以及对已有化石材料的初步修订 ,到目前为止 ,陕西蓝田灞河组共计发现哺乳动物化石 45种 ,蓝田组 2 0种。新的化石证据表明 ,灞河组发现的哺乳动物化石组合完全不同于典型意义上的保德三趾马动物群。大哺乳动物化石以灞河三趾马与贾氏三趾马为代表 ,牛科化石组合在种级甚至属级上有明显的区别。大量的陕西转角羚羊 ,小型的Protoryx、Dorcadoryx以及Ga     

内蒙古中部中新世最晚期三趾马化石的新发现

<正>三趾马属(Hipparion)广泛分布于北美和旧大陆,它们在欧亚大陆的晚中新世和上新世期间特别繁盛,是地层对比和环境重建的重要生物标志。丰富的三趾马化石标本发现于中国许多的化石地点,主要产自红土堆积中。内蒙古中部的三趾马化石此前也发现于红土堆积,如化德县土城子和四子王旗乌兰花。这个地区的河湖相沉积中发现了大量小哺乳动物化石地点,但其中却很少有三趾马化石的报道,更缺乏详细的描述。     

《中国的三趾马化石》——解放后我国第一部全面介绍三趾马化石的专著

三趾马化石在生物进化的研究历史中起过重要的作用,它对阐明进化理论和确定地层时代都有很重要的意义.三趾马是哺乳动物化石中少数几个分布最广,发现效率最高的标准化石之一,犹如无脊椎动物化石中的三叶虫和纺锤虫等.我国是三趾马化石极为丰富的国家,但三趾马化石的鉴定在我国却是一个老大难问题.解放前,瑞典     

临夏故事

临夏盆地位于青藏高原东北缘 ,晚新生代地层发育 ,蕴藏着丰富的哺乳动物化石。自上个世纪 5 0年代以来这里就盛产作为中药材的“龙骨” ,实际上就是大型的哺乳动物化石 ,可惜的是很少被作为科学研究的材料。最近 ,我们已在从晚渐新世至早更新世的各个层位中发现了大量的哺乳动物化石 ,包括晚渐新世的巨犀动物群、中中新世的铲齿象动物群、晚中新世的三趾马动物群和早更新世的真马动物群 ,尤其以三趾马动物群最为丰富 ,以鼬、剑齿虎、鬣狗、四棱齿象、三趾马、犀牛、弓颌猪、长颈鹿、麝牛和羚羊等为代表。临夏盆地的三趾马动物群化石在数量和…     

中国和其他全北界三趾马的头骨和头后骨骼形态比较(英文)

由于地理位置上处于北美和旧大陆西部之间,中国晚中新世的三趾马提供了重要的生物地层与生物地理信息。这些信息反映出晚中新世时期北美和欧亚大陆之间的动物群交流,同时也与当时的古环境变迁相关联。依据面部和牙齿形态以及肢骨比例,将中国的三趾马与欧亚大陆及北美的其他种类进行了对比。中国的三趾马可识别出两个分类类群,其中一个非系统发育意义上的类群包括 Hipparion dermatorhinum,H. weihoense,H. fossatum,H. hippidio-dus 和 H. coelophyes,这一类群与旧大陆西部的三趾马在形态上高度相似; 另一个为本土类群,包括 H. ptychodus,H. platyodus,H. tylodus,H. sefvei 和 H. plocodus,它们与其他地区的种类并无相似之处。前一个类群是中国北方草原型动物群中的典型分子,对欧亚大陆化石地点的生物地层对比相当重要; 后一类群与北美的三趾马( "Cormohipparion"属) 在面部形态上具有相似性,这些本土的三趾马是中国北方森林型动物群的分子。     

甘肃天祝松山第二地点中上新世小哺乳动物

<正> 1980年夏作者在甘肃天祝藏族自治县松山公社处理人民来信过程中,在80007地点采得几块含化石骨片的红粘土结核标本。这些标本经室内水洗,从中获得一些零星但相当有意义的小哺乳动物化石材料。这些化石的发现不但对于早先记述的80006地点的小哺乳动物群作了进一步的充实,而且对更深入认识中国北方三趾马动物群也有一定的意义。     

柴达木盆地晚中新世三趾马化石

Bohlin描述的柴达木动物群中的三趾马材料非常少 ,仅能证明三趾马在这个地点的存在。近年来新的野外考察在这一地区发现了更多的三趾马化石材料 ,至少包括 3个种 ,即Hipparioncf.H .chiai、H .weihoense和H .teilhardi。H .cf.H .chiai和H .weihoense在柴达木盆地的发现进一步证实了晚中新世早期 (保德早期 )动物群在这个地区的存在。柴达木盆地的H .teilhardi基本上与H .cf.H .chiai和H .weihoense产自同一层位 ,其时代也应为保德早期。H .cf.H .chiai和H .weihoense在柴达木盆地的发现为该地区在晚中新世早期为草原型环境的判断提供了更多的证据。H .teilhardi更细长的远端肢骨也是对开阔环境的一种适应性状     

内蒙古韩家营玄武岩夹层中三趾马动物群化石（英文）

内蒙古乌兰察布市集宁区韩家营村附近发现了一处夹在两层玄武岩之间的三趾马动物群化石地点。通过K-Ar同位素测年,确定了上、下两层玄武岩的年代分别为6.8和7.2Ma。与中国北方其他三趾马动物群相比,韩家营三趾马动物群与山西保德、内蒙古四子王旗以及甘肃临夏盆地的三趾马动物群非常相似。保德第43、44、49地点与韩家营的动物群组成类似,表明这几个地点的时代约为7.0 Ma而不是5.5 Ma。内蒙古四子王旗乌兰花地点与韩家营的化石类群也十分相像,证实了该动物群年龄约为7 Ma。对比甘肃临夏盆地的动物群,柳树组上部的杨家山三趾马动物群与韩家营的更接近。韩家营动物群的组成和牙齿结构表明其属于中国晚中新世的西部生物区系Gazella dorcadoides动物群。     

北京凤凰山化石地点发掘简报

北京凤凰山地点位于周口店北京猿人遗址以北8km处, 是一处含哺乳动物化石与灰烬的洞穴-裂隙堆积。该地点包括两个化石层,上层为洞外的冲积物, 由棕红色黏土组成, 靠下部发现有零星的、破碎的化石, 可鉴定出似鸡骨山狐(Vulpes cf.chikushanensis)和羚羊(Antelopinae)两种类型; 下层含有灰烬层, 出土了较为丰富的哺乳动物化石, 可鉴定的哺乳动物化石包括鬣狗(Hyaenidae)、三门马(Equus sameniensis)、犀(Rhinocerotidae)、李氏野猪(Sus lydekkeri)、肿骨大角鹿(Megaloceros pachyosteus)、葛氏斑鹿(Cervus(Sika)grayi)、水牛(Bubalus sp.), 共7种。动物群与周口店第一地点和南京人化石地点的动物群相似, 指示该地点化石层的时代可能为中更新世。部分骨骼表面痕迹与灰烬层的发现显示该地点可能不排除有古人类活动痕迹的存在。     

西藏吉隆盆地三趾马化石新地点及相关的青藏高原隆升问题的修正意见(节选)

2000年6月,作者在西藏吉隆盆地沃马村北吉隆河左岸晚中新世地层发现一三趾马的左DP2(第二乳上前臼齿)及若干脊椎动物破碎化石骨片。该化石地点不同于位于沃马乡西北1km黑沟中的著名三趾马化石地点,而位于黄万波等记述的“吉隆南峡谷中间剖面”,过去仅发现脊椎动物骨骼碎片及植物化石碎屑,因此是一个新发现的三趾马化石地点。虽然材料零星,但对于将来的研究工作可以提供一点线索,故报道于此。同时,依据生态学原理对过去依据三趾马动物群对青藏高原隆升问题作出的推断提出了初步的修正意见。在关于青藏高原隆升问题的研究中,古生物学曾起到过…     

Nest desertion cannot be considered an egg‐rejection mechanism in a medium‐sized host: an experimental study with the common blackbird Turdus merula

Two main mechanisms of egg rejection, the main defence of hosts against brood parasites, have been described: ejection and desertion. Desertion of the parasitized nest is much more costly and is usually exhibited by small‐sized host species unable to remove the parasitic egg. However, nest desertion is frequently assumed to be an anti‐parasite strategy even in medium or large‐sized host species. This assumption should be considered with caution because: 1) large‐sized hosts able to eject the parasitic egg should eject it rather than desert the nest, and 2) breeding birds may desert their nests in response to different disturbances other than brood parasitism. This problem is especially important in the common blackbird Turdus merula because this is a medium‐sized species, potential host of the common cuckoo Cuculus canorus, in which desertion has been frequently reported as a response to cuckoo egg models. Here, we seek to determine whether nest desertion can be considered a response unequivocally directed to the parasitic egg in medium‐sized hosts using the blackbird as the study species. In an experimental study in which we have manipulated levels of mimicry and size of experimental eggs, we have found that both colour (mimetic and non‐mimetic; at least for human vision) and size (small, medium, and large) significantly affected ejection rates but not nest desertion rates. In fact, although large eggs disproportionally provoked nest desertion more frequently than did small or medium‐sized eggs, cuckoo‐sized parasitic eggs were not deserted allowing us to conclude that desertion is unlikely to be an adaptive response to brood parasitism at least for this species.     

Association of the invasive Haemaphysalis longicornis tick with vertebrate hosts,other native tick vectors,and tick-borne pathogens in New York City,USA

Haemaphysalis longicornis, the Asian longhorned tick, is an invasive ixodid tick that has rapidly spread across the northeastern and southeastern regions of the United States since first reported in 2017. The emergence of H. longicornis presents a potential threat for livestock, wildlife, and human health as the host associations and vector potential of this invasive pest in the United States are poorly understood. Previous field data from the United States has shown that H. longicornis was not associated with natural populations of small mammals or birds, but they show a preference for medium sized mammals in laboratory experiments. Therefore, medium and large sized mammals were sampled on Staten Island, New York, United States, to determine H. longicornis host associations and vector potential for a range of human and veterinary pathogens. A total of 97 hosts were sampled and five species of tick (Amblyomma americanum, Dermacentor variabilis, H. longicornis, Ixodes scapularis, Ixodes cookei) were found feeding concurrently on these hosts. Haemaphysalis longicornis was found in the highest proportions compared with other native tick species on raccoons (55.4%), Virginia opossums (28.9%), and white-tailed deer (11.5%). Tissue, blood, and engorged larvae were tested for 17 different pathogens using a nanoscale PCR platform. Infection with five pathogens (Borrelia burgdorferi, Anaplasma phagocytophilum, Rickettsia spp., Mycoplasma haemocanis, and Bartonella spp.) was detected in host samples, but no pathogens were found in any larval samples. These results suggest that although large and medium sized mammals feed large numbers of H. longicornis ticks in the environment, there is presently a low potential for H. longicornis to acquire pathogens from these wildlife hosts.     

Host-parasite relationships of the genus Hyalomma Koch, 1844 (Acari, Ixodidae) and their connection with microevolutionary process

Host-parasite relationships of Hyalomma species of the world fauna are analyzed. The majority of species infests predominately various mammals. Birds and reptiles are used as preferred hosts by several Hyalomma species, and only on certain stage: adults of H. aegyptium parasitize tortoises; immature stages of H. marginatum parasitize birds. It is hypothesized that relationships of H. aegyptium adults (subgenus Hyalomma s. str.) with reptiles are secondarily in origin. Immature stages of H. aegyptium retain the primary wide diapason of hosts, which are various small mammals, birds and reptiles. The life cycle of this species is the three-host type that is considered as a primary type in ixodid ticks. A typical scheme of relationships with their hosts in all well-examined Hyalommina species has following features: the adult stage parasitize large and medium sized mammals, immature stages parasitize small mammals, three-host life cycle. A variety of preferred hosts and types of life cycle is observed in the subgenus Euhyalomma. All species of this subgenus can be arranged into two groups. In the first group, the immature stages infest only small mammals and birds, and the adults parasitize large mammals; this type of host preferences is probably primary host-parasite relationships of Hyalomma. This group includes: H. albiparmatum, H. asiaticum, H. excavatum, H. franchinii, H. impeltatum, H. impressum, H. lusitanicum, H. marginatum, H. nitidum, H. schulzei, and H. truncatum. Hyalomma marginatum and H. schulzei are two-host species; H. excavatum is two- or three-host tick. All the remaining species (except H. albiparmatum, which life cycle is unknown) are three-host ticks. In the second group, the immature stages as well as the adult stage parasitize large mammals. This group includes: H. dromedarii, H. anatolicum, and H. scupense. These species are two- or one-host ticks.     

Availability of optimal‐sized prey affects global distribution patterns of the golden eagle Aquila chrysaetos

Climate and landscape change are expected to significantly affect trophic interactions, which will especially harm top predators such as the golden eagle Aquila chrysaetos. Availability of optimal prey is recognized to influence reproductive success of raptors on a regional scale. For the golden eagle, medium‐sized prey species between 0.5 and 5 kg are widely considered to be optimal prey during the breeding season, whereas smaller and larger species are deemed as energetically sub‐optimal. However, knowledge about the effects of optimal prey availability is still scarce on larger scales. To decrease this apparent knowledge gap, we combined biogeographical information on range margins with information about the foraging behaviour and reproductive success of golden eagles from 67 studies spanning the Northern Hemisphere. We hypothesized that availability of optimal prey will affect foraging behaviour and breeding success and, thus, distribution patterns of the golden eagle not only on a local but also on a continental scale. We correlated the diet breadth quantifying foraging generalism, breeding success and proportions of small (< 0.5 kg), medium (0.5–5 kg) and large‐sized (> 5 kg) prey species within the diet with the minimum distance of the examined eagles to the actual species distribution boundary. Closer to the range edge, we observed decreased proportions of medium‐sized prey species and decreasing breeding success of golden eagles. Diet breadth as well as proportions of small and large‐sized prey species increased, however, towards the range edge. Thus, availability of optimal‐sized prey species seems to be a crucial driver of foraging behaviour, breeding success and distribution of golden eagles on a continental scale. However, underlying effects of landscape characteristics and human influence on optimal prey availability has to be investigated in further large‐scale studies to fully understand the major threats facing the golden eagle and possibly other large terrestrial birds of prey.     

Small and medium sized mammals as predators of ticks (Ixodoidea) in South Africa

A total of 1,640 stomach contents from 56 South African species of small and medium sized mammals were examined for ticks. Only six ticks were found in three specimens of the caracal Felis caracal. Although identification of the tick species was not possible owing to fragmentation and partial digestion, the genus Haemaphysalis was represented in four of these cases. We conclude that predation by small and medium sized mammals on ticks is uncommon in South Africa.     

Dietary Spectrum of Two Sympatric Canid Species in Ladakh,India

We have conducted a study between May and August 2013 to understand the dietary spectrum of two canid species: Tibetan wolf (Canis lupus chanco) and Red fox (Vulpes vulpes) in one of the most inhospitable landscape of the world. Ladakh is characterized by harsh environmental conditions and low primary productivity and therefore animal populations, particularly of large and medium sized herbivores are also low and sparsely distributed. This in turn poses a challenge to the survival of predators. We have attempted to investigate the ways by which the two sympatric canid species are optimizing feeding for their survival in an environment where there is scarcity of wild prey base. Scats of the two species were collected from Chiktan and Rangdum valleys and undigested food remnants were identified. The dietary spectrum of Tibetan wolf was composed of six prey species (2 wild and 4 livestock species). The share of livestock species in the diet was maximum (RO: 62.0%). The Red fox being an opportunistic feeder consumed 19 forgeable items, including small and medium sized mammals, birds, reptiles, insects, plant material, eggs, stones and debris. The livestock species contributed maximum to the diet of Red fox (RO: 22.9%). The dietary niche breadths of both species were more or less similar (0.53 and 0.58) and indicating a generalist feeding behavior. Both the species are surviving in the same environment with a dietary overlap of 0.60. The given information is expected to aid further studies in Indian Trans-Himalaya.     

Predation by feral cats threatens great albatrosses

Biological Invasions - Feral cats (Felis catus) are a potential threat for several seabird species including medium sized albatrosses, but studies documenting predation behavior, demographic...     

Does underwater flash photography affect the behaviour,movement and site persistence of seahorses?

The effect of flash photography on seahorse species has never been tested. An experiment was established to test the effect of flash photography and the handling of Hippocampus whitei, a medium‐sized seahorse species endemic to Australia, on their behavioural responses, movements and site persistence. A total of 24 H. whitei were utilized in the experiment with eight in each of the three treatments (flash photography, handling and control). The effect of underwater flash photography on H. whitei movements was not significant; however, the effect of handling H. whitei to take a photograph had a significant effect on their short‐term behavioural responses to the photographer. Kaplan–Meier log‐rank test revealed that there was no significant difference in site persistence of H. whitei from each of the three treatments and that flash photography had no long‐term effects on their site persistence. It is concluded that the use of flash photography by divers is a safe and viable technique with H. whitei, particularly if photographs can be used for individual identification purposes.     

Body mass, habitat generality, and avian community composition in forest remnants

Aim Many theories of biodiversity and biogeography assume that species respond equally to variability in habitat area and isolation. This assumption does not allow for differential responses due to interspecific competition or other mechanisms, and therefore does not allow community composition to be predicted. As body size is relevant to area requirements and interspecific dominance, a natural experiment was conducted to quantify the differential responses of avian species abundance to variability in remnant area, isolation and forest cover based on average species body mass. Location Deciduous forest remnants of varying area and isolation throughout the State of Delaware, USA. Methods Forest remnants within stratified area and isolation classes were randomly selected for breeding bird surveys; total forest cover (ha) within 2 km of each survey point was subsequently determined as a covariate. Surveys were conducted within 100–150 m from the edge of each remnant and detected bird species were divided into five classes based on a log₂‐transformation of body mass (very small, small, medium, large and very large). Assuming a negative binomial distribution, the abundance of detected individuals in each mass class was analysed using generalized linear models with remnant area, isolation, local forest cover and two‐way interactions specified as independent variables. The same analyses were conducted for individual species where sample size allowed. Results Very small, small and very large bodied species decreased in abundance with decreasing local forest cover and remnant area and with increasing remnant isolation, while large species increased in abundance. Medium‐sized species decreased in abundance with increasing forest cover, did not respond to remnant isolation and showed a concave, curvilinear response to increasing remnant area. Large and medium‐sized species were the most abundant birds in small, isolated remnants despite occurring in the largest remnants with the more abundant very small and small species, suggesting that communities are not randomly organized. Main conclusions Regardless of presumed habitat associations, large and medium‐sized species are of the appropriate size to be dominant competitors when forest resources are limiting, and thus may be considered ‘generalists’. The smallest species may be excluded entirely from small, isolated remnants even though such remnants meet their ecological needs; the needs of very large species are not met in small remnants. The applicability of biodiversity theories to community composition, species abundance and, by extension, to conservation, can be improved by incorporating differential responses based on body mass into their assumptions.     

Living in the danger zone: Exposure to predators and the evolution of spines and body armor in mammals

Mammals have independently evolved a wide variety of morphological adaptations for use in avoiding death by predation, including spines, quills, dermal plates, and noxious sprays. Although these traits appear to protect their bearer from predatory attack, it is less obvious why some species evolved them and others have not. We investigated the ecological correlates favoring the evolution of specialized defenses in mammals, focusing on conspicuousness to predators due to body size and openness of habitat. We scored species for the degree to which they are protected by spines, quills, dermal plating, and sprays and used phylogenetic comparative analyses to study the morphological and ecological factors that may favor their evolution. We show that medium‐sized insectivorous mammals (～800 g to 9 kg) that live in open habitats are more likely to possess one of these defensive traits to reduce predation. Smaller species (<200 g) and those in closed habitats can typically rely on crypsis to avoid predators, and larger species (>10 kg) are less susceptible to predation by most small‐ to medium‐sized predators. We discuss how diet, metabolic rate, and defensive strategy evolve in concert to allow species to exploit this ecomorphological “danger zone” niche.