• 【Palaeoamyda messeliana nov。梳子。来自始新世Messel坑和Geiseltal地区的(Testudines,Pan-Trionychidae)分类学和系统发育学见解。】 复制标题 收藏 收藏
    DOI:10.7717/peerj.2647 复制DOI
    作者列表:Cadena E
    BACKGROUND & AIMS: BACKGROUND:Abundant pan-trionychid (soft-shell) turtles specimens have been found in Eocene sequences of central Europe, particularly from two localities in Germany, the Messel Pit (a UNESCO World Natural Heritage Site) and Geiseltal, traditionally attributed to Trionyx messelianus or Rafetoides austriacus. Over the last two decades new specimens of this taxon from these two localities have been discovered and fully prepared. However, they have remained unstudied, as well as their phylogenetic position inside Pan-Trionychidae is unknown. RESULTS:Five new specimens of Palaeoamyda messeliana nov. comb. from Messel Pit and Geiseltal localities are fully described here. A revised diagnosis for the species is also presented here, together with its inclusion in a phylogenetic analysis of Pan-Trionychidae that shows that this species is sister to the extant Amyda cartilaginea, one of the most abundant pan-trionychid (soft-shell) turtles from Asia, both members of the clade Chitrini. The specimens described in here are among the best and most complete fossil pan-trionychid skeletons so far known.
    背景与目标: 背景:在中欧始新世时期发现了大量的泛甲tri甲标本,特别是在德国的两个地方,即梅塞尔·皮特(联合国教科文组织世界自然遗产)和盖世塔尔(Geiseltal),传统上归因于Trionyx messelianus或南非腊肠。在过去的二十年中,已经发现并充分准备了来自这两个地方的该分类单元的新标本。然而,它们尚未得到研究,并且它们在泛甲Tri科内的系统发育位置尚不清楚。
    结果:五个新标本的新标本。梳子。来自Messel Pit的地点和Geiseltal地点在此处得到了充分描述。此处还提供了对该物种的修订诊断,并将其包含在泛-甲的系统发育分析中,该分析表明该物种是现存的八角cart甲(最丰富的泛tri甲(pan)之一)的姊妹姐妹。来自亚洲的Chitrini分支成员。这里描述的标本是迄今已知的最好和最完整的化石泛三生肖骨骼。
  • 【梅塞尔化石遗址的始新世早期鸟类:一个拥有4,800万年历史的鸟类群落,为热带鸟类的进化提供了时间上的视角。】 复制标题 收藏 收藏
    DOI:10.1111/brv.12274 复制DOI
    作者列表:Mayr G
    BACKGROUND & AIMS: :Birds play an important role in studies addressing the diversity and species richness of tropical ecosystems, but because of the poor avian fossil record in all extant tropical regions, a temporal perspective is mainly provided by divergence dates derived from calibrated molecular analyses. Tropical ecosystems were, however, widespread in the Northern Hemisphere during the early Cenozoic, and the early Eocene German fossil site Messel in particular has yielded a rich avian fossil record. The Messel avifauna is characterized by a considerable number of flightless birds, as well as a high diversity of aerial insectivores and the absence of large arboreal birds. With about 70 currently known species in 42 named genus-level and at least 39 family-level taxa, it approaches extant tropical biotas in terms of species richness and taxonomic diversity. With regard to its taxonomic composition and presumed ecological characteristics, the Messel avifauna is more similar to the Neotropics, Madagascar, and New Guinea than to tropical forests in continental Africa and Asia. Because the former regions were geographically isolated during most of the Cenozoic, their characteristics may be due to the absence of biotic factors, especially those related to the diversification of placental mammals, which impacted tropical avifaunas in Africa and Asia. The crown groups of most avian taxa that already existed in early Eocene forests are species-poor. This does not support the hypothesis that the antiquity of tropical ecosystems is key to the diversity of tropical avifaunas, and suggests that high diversification rates may be of greater significance.
    背景与目标: :鸟类在解决热带生态系统的多样性和物种丰富性的研究中起着重要作用,但是由于在所有现存的热带地区鸟类化石记录不佳,所以从校准分子分析得出的分歧日期主要提供了时间上的观点。然而,在新生代早期,热带生态系统在北半球广泛分布,尤其是始新世早期的德国化石遗址梅塞尔(Messel)已产生了丰富的鸟类化石记录。 Messel航空动物的特点是有相当数量的不会飞的鸟,以及大量的食虫动物,并且没有大型的树栖鸟类。它以42个命名属级别和至少39个家庭级别的分类单元中的大约70种目前已知的物种,在物种丰富度和分类学多样性方面接近于现存的热带生物区系。就其分类学组成和假定的生态特征而言,“梅塞尔”航空动物更类似于新热带,马达加斯加和新几内亚,而不是非洲大陆和亚洲的热带森林。由于以前的区域在大多数新生代都在地理上是孤立的,因此它们的特征可能是由于缺乏生物因素,尤其是那些与胎盘哺乳动物多样化有关的因素,从而影响了非洲和亚洲的热带鸟类。早始新世森林中已经存在的大多数鸟类分类单元的冠群种类少。这不支持热带生态系统的古代是热带鸟类的多样性的关键这一假设,并表明较高的多样化率可能具有更大的意义。
  • 【在古新世-始新世最热时期,北美最古老的灵长类动物和哺乳动物生物地理。】 复制标题 收藏 收藏
    DOI:10.1073/pnas.0710180105 复制DOI
    作者列表:Beard KC
    BACKGROUND & AIMS: :Undoubted primates first appear almost synchronously in the fossil records of Asia, Europe, and North America. This temporal pattern has complicated efforts to reconstruct the early dispersal history of primates in relation to global climate change and eustatic fluctuations in sea level. Here, I describe fossils from the Tuscahoma Formation on the Gulf Coastal Plain of Mississippi documenting an anatomically primitive species of Teilhardina that is older than other North American and European primates. Consistent with its antiquity, a phylogenetic analysis of dental characters recognizes Teilhardina magnoliana, sp. nov., as the most basal member of this genus currently known from either North America or Europe. Its stratigraphic provenance demonstrates that primates originally colonized North America near the base of the Paleocene-Eocene Thermal Maximum (PETM), but before an important fall in eustatic sea level. Correlation based on carbon isotope stratigraphy and sequence stratigraphy indicates that the earliest North American primates inhabited coastal regions of the continent for thousands of years before they were able to colonize the Rocky Mountain Interior. The transient provincialism displayed by early North American primates corresponds to similar biogeographic patterns noted among fossil plants. Decreased precipitation in the Rocky Mountain Interior during the early part of the PETM may have been an important factor in maintaining biotic provincialism within North America at this time. These results underscore the need to obtain multiple, geographically dispersed records bearing on significant macroevolutionary events such as the PETM.
    背景与目标: :毫无疑问的灵长类动物几乎首先在亚洲,欧洲和北美的化石记录中同时出现。这种时间模式为重建灵长类动物与全球气候变化和海平面的欣喜波动有关的早期散布历史付出了复杂的努力。在这里,我描述了密西西比州墨西哥湾沿岸平原Tuscahoma组的化石,记录了Teilhardina的解剖学原始物种比其他北美和欧洲的灵长类动物更古老。根据其古代,对牙齿特征的系统发育分析可识别Teilhardina magnoliana,sp。十一月,作为该属中最基础的成员,目前已知于北美或欧洲。它的地层证据表明,灵长类动物最初定居在古新世-始新世热最大值(PETM)附近的北美地区,但在海平面没有明显下降之前。基于碳同位素地层学和层序地层学的相关性表明,最早的北美灵长类动物曾在该大陆的沿海地区居住了数千年,然后才得以殖民落基山脉内部。北美早期灵长类动物所表现出的短暂的地方主义与化石植物中注意到的相似的生物地理模式相对应。在PETM早期,落基山内陆降水的减少可能是目前维持北美生物多样性的一个重要因素。这些结果强调需要获得与重要的宏观进化事件(例如PETM)有关的多个,地理位置分散的记录。
  • 【始新世温暖的海洋过程和碳循环。】 复制标题 收藏 收藏
    DOI:10.1098/rsta.2013.0099 复制DOI
    作者列表:John EH,Pearson PN,Coxall HK,Birch H,Wade BS,Foster GL
    BACKGROUND & AIMS: :Sea surface and subsurface temperatures over large parts of the ocean during the Eocene epoch (55.5-33.7 Ma) exceeded modern values by several degrees, which must have affected a number of oceanic processes. Here, we focus on the effect of elevated water column temperatures on the efficiency of the biological pump, particularly in relation to carbon and nutrient cycling. We use stable isotope values from exceptionally well-preserved planktonic foraminiferal calcite from Tanzania and Mexico to reconstruct vertical carbon isotope gradients in the upper water column, exploiting the fact that individual species lived and calcified at different depths. The oxygen isotope ratios of different species' tests are used to estimate the temperature of calcification, which we converted to absolute depths using Eocene temperature profiles generated by general circulation models. This approach, along with potential pitfalls, is illustrated using data from modern core-top assemblages from the same area. Our results indicate that, during the Early and Middle Eocene, carbon isotope gradients were steeper (and larger) through the upper thermocline than in the modern ocean. This is consistent with a shallower average depth of organic matter remineralization and supports previously proposed hypotheses that invoke high metabolic rates in a warm Eocene ocean, leading to more efficient recycling of organic matter and reduced burial rates of organic carbon.
    背景与目标: :始新世(55.5-33.7 Ma)期间,海洋大部分地区的海表和地下温度超过现代值几度,这一定会影响许多海洋过程。在这里,我们关注水柱温度升高对生物泵效率的影响,尤其是与碳和养分循环有关。我们利用来自坦桑尼亚和墨西哥的保存完好的浮游有孔方解石的稳定同位素值,利用各个物种在不同深度生活和钙化的事实,来重建上部水柱中的垂直碳同位素梯度。使用不同物种的测试的氧同位素比率来估算钙化温度,我们使用一般循环模型生成的始新世温度剖面将其转化为绝对深度。使用来自同一地区的现代核心-顶部组件的数据说明了这种方法以及潜在的陷阱。我们的结果表明,在始新世中期和中新世期间,通过上层热跃层的碳同位素梯度比现代海洋要陡峭(并且更大)。这与较浅的平均有机物再矿化深度相一致,并支持先前提出的假说,这些假说在温暖的始新世海洋中引起高代谢率,从而导致有机物更有效地循环利用和降低有机碳的掩埋率。
  • 【Cocos sahnii Kaul:来自印度西部拉贾斯坦邦的始新世雨林的一种Cocos nucifera L.果实。】 复制标题 收藏 收藏
    DOI:10.1007/s12038-012-9233-3 复制DOI
    作者列表:Shukla A,Mehrotra RC,Guleria JS
    BACKGROUND & AIMS: :Cocos sahnii Kaul, a fossil palm fruit, is validated and described from the Fuller's earth deposits of Kapurdi village of Rajasthan considered as Early Eocene in age. The fossil best resembles the genus Cocos, particularly Cocos nucifera L., which is now a common coastal element thriving in highly moist conditions. The recovery of this coconut-like fruit, along with earlier described evergreen taxa from the same formation, suggests the existence of typical tropical, warm and humid coastal conditions during the depositional period. The present arid to semi-arid climatic conditions occurring in Rajasthan indicate drastic climate change in the region during the Cenozoic. The possible time for the onset of aridity in the region which caused the total eradication of semi-evergreen to evergreen forests is discussed, as well as the palaeobiogeography of coconuts.
    背景与目标: :Cocos sahnii Kaul是一种化石棕榈果,已通过在拉贾斯坦邦的Kapurdi村的富勒大地矿床进行了验证和描述,该村被认为是早始新世。化石最像可可属,特别是可可椰子,现在已成为在高度潮湿的条件下蓬勃发展的常见沿海元素。从相同的形态中回收这种椰子样水果以及较早描述的常绿类群,表明在沉积期存在典型的热带,温暖和潮湿的沿海条件。拉贾斯坦邦目前的干旱至半干旱气候条件表明,新生代期间该地区发生了剧烈的气候变化。讨论了该地区干旱的发生时间,该时间导致了半常绿到常绿森林的彻底消灭,以及椰子的古生物地理学。
  • 【Siamopithecus eocaenus,一种来自泰国的始新世晚期类人猿灵长类动物:它对东南亚类人猿进化的贡献。】 复制标题 收藏 收藏
    DOI:10.1006/jhev.1999.0291 复制DOI
    作者列表:Ducrocq S
    BACKGROUND & AIMS: Dental remains of a late Eocene anthropoid primate from Thailand, Siamopithecus eocaenus, have been recently reported; complete description and comparisons of this material are given here. Siamopithecus displays several derived dental features that suggest close phylogenetic affinities among the Thai species, the Burmese Pondaungia, and the North African and Omani propliopithecines Aegyptopithecus and Moeripithecus. The geographic origin of anthropoid primates cannot be securely determined at present, but the available fossil record indicates that faunal exchanges between Africa and Southeast Asia were very probable during the Eocene, and that direct relationships between Asian and African anthropoid primates can be inferred.

    背景与目标: 最近有报道说,来自泰国的始新世晚期人猿灵长类动物,Siamopithecus eocaenus,有牙齿遗骸。在此给出了对该材料的完整描述和比较。 Siamopithecus显示出一些衍生的牙齿特征,表明泰国物种,缅甸Pondaungia,北非和阿曼propliopithecines Aegyptopithecus和Moeripithecus之间具有密切的系统发生亲缘关系。目前尚不能确定人猿的地理起源,但现有的化石记录表明,始新世期间非洲和东南亚之间的动物交流非常可能,并且可以推断出亚洲和非洲人猿的直接关系。

  • 【来自埃及始新世晚期的扁豆尿素和畸胎动物的颅骨材料,以及简约和贝叶斯方法在斑纹齿科(系统发育和生物地理学)(Placentalia,Mammalia)中的应用。】 复制标题 收藏 收藏
    DOI:10.7717/peerj.2639 复制DOI
    作者列表:Borths MR,Holroyd PA,Seiffert ER
    BACKGROUND & AIMS: :Hyaenodonta is a diverse, extinct group of carnivorous mammals that included weasel- to rhinoceros-sized species. The oldest-known hyaenodont fossils are from the middle Paleocene of North Africa and the antiquity of the group in Afro-Arabia led to the hypothesis that it originated there and dispersed to Asia, Europe, and North America. Here we describe two new hyaenodont species based on the oldest hyaenodont cranial specimens known from Afro-Arabia. The material was collected from the latest Eocene Locality 41 (L-41, ∼34 Ma) in the Fayum Depression, Egypt. Akhnatenavus nefertiticyon sp. nov. has specialized, hypercarnivorous molars and an elongate cranial vault. In A. nefertiticyon the tallest, piercing cusp on M1-M2 is the paracone. Brychotherium ephalmos gen. et sp. nov. has more generalized molars that retain the metacone and complex talonids. In B. ephalmos the tallest, piercing cusp on M1-M2 is the metacone. We incorporate this new material into a series of phylogenetic analyses using a character-taxon matrix that includes novel dental, cranial, and postcranial characters, and samples extensively from the global record of the group. The phylogenetic analysis includes the first application of Bayesian methods to hyaenodont relationships. B. ephalmos is consistently placed within Teratodontinae, an Afro-Arabian clade with several generalist and hypercarnivorous forms, and Akhnatenavus is consistently recovered in Hyainailourinae as part of an Afro-Arabian radiation. The phylogenetic results suggest that hypercarnivory evolved independently three times within Hyaenodonta: in Teratodontinae, in Hyainailourinae, and in Hyaenodontinae. Teratodontines are consistently placed in a close relationship with Hyainailouridae (Hyainailourinae + Apterodontinae) to the exclusion of "proviverrines," hyaenodontines, and several North American clades, and we propose that the superfamily Hyainailouroidea be used to describe this relationship. Using the topologies recovered from each phylogenetic method, we reconstructed the biogeographic history of Hyaenodonta using parsimony optimization (PO), likelihood optimization (LO), and Bayesian Binary Markov chain Monte Carlo (MCMC) to examine support for the Afro-Arabian origin of Hyaenodonta. Across all analyses, we found that Hyaenodonta most likely originated in Europe, rather than Afro-Arabia. The clade is estimated by tip-dating analysis to have undergone a rapid radiation in the Late Cretaceous and Paleocene; a radiation currently not documented by fossil evidence. During the Paleocene, lineages are reconstructed as dispersing to Asia, Afro-Arabia, and North America. The place of origin of Hyainailouroidea is likely Afro-Arabia according to the Bayesian topologies but it is ambiguous using parsimony. All topologies support the constituent clades-Hyainailourinae, Apterodontinae, and Teratodontinae-as Afro-Arabian and tip-dating estimates that each clade is established in Afro-Arabia by the middle Eocene.
    背景与目标: 斑牙don属是食肉性哺乳动物的一种不同的,灭绝的群体,其中包括黄鼠狼到犀牛大小的物种。最著名的透明牙齿化石来自北非中古新世,该集团在非洲-阿拉伯的上古时期导致了这一假说起源于该地区并散布到亚洲,欧洲和北美。在这里,我们根据从非洲-阿拉伯共和国已知的最古老的鬣狗颅骨标本描述两种新的鬣狗牙种。该材料是从埃及Fayum凹陷最新的始新世地方41(L-41,约34 Ma)收集的。 Akhnatenavus nefertiticyon sp。十一月有专门的,食肉性高的臼齿和细长的颅骨穹顶。在A. nefertiticyon中,M1-M2上最高的,刺穿的尖尖是对位圆锥形。 Brychotherium ephalmos gen。等十一月具有更广泛的臼齿,保留了前锥体和复杂的距骨。在麻疯树(B. ephalmos)中,M1-M2上最高的,刺穿的尖头是元圆锥。我们使用字符分类单元矩阵将这种新材料纳入一系列的系统发育分析中,该矩阵包括新颖的牙齿,颅骨和颅后字符,并从该小组的全球记录中广泛获取样本。系统发育分析包括将贝叶斯方法首次应用于透明牙齿关系。依法将B. ephalmos始终放置在Teratodontinae(一种具有多种通体和肉食性形式的非裔阿拉伯进化枝)中,并且Akhnatenavus一直在Hyainailourinae中作为非裔阿拉伯辐射的一部分被回收。系统发育结果表明,高食肉动物在斑牙齿independently内独立进化了三次:在畸齿龙齿科,Hyainailourinae和斑牙齿tina科。畸齿动物一直与Hyainailouridae(Hyainailourinae Apterodontinae)保持密切的关系,但排除了“ proverrrines”,hyenenodontines和一些北美进化枝,我们建议使用超家族Hyainailouroidea来描述这种关系。使用从每种系统发育方法中恢复的拓扑,我们使用简约优化(PO),似然性优化(LO)和贝叶斯二进制马尔可夫链蒙特卡洛(MCMC)重建了斑纹齿bio的生物地理历史,以检验对斑纹齿f的非洲阿拉伯起源的支持。在所有分析中,我们都发现了斑纹牙most很可能起源于欧洲,而不是非洲-阿拉伯。通过尖端日期分析估计该进化枝在白垩纪晚期和古新世经历了快速辐射。目前没有化石证据记录的辐射。在古新世期间,世系被重建并扩散到亚洲,非洲-阿拉伯和北美。根据贝叶斯拓扑,Hynailnailoidoidea的产地可能是非洲-阿拉伯,但使用简约法则是模棱两可的。所有拓扑都支持组成类进化支-Hyainailourinae,Apterodontinae和Teratodontinae-非洲裔阿拉伯人,据先验估计,每个进化枝都是在中新世中期在非洲裔阿拉伯人中建立的。
  • 【始新世梅塞尔页岩中的同位素组成和有机分子的可能起源。】 复制标题 收藏 收藏
    DOI:10.1038/329048a0 复制DOI
    作者列表:Hayes JM,Takigiku R,Ocampo R,Callot HJ,Albrecht P
    BACKGROUND & AIMS: :The sediments that now comprise the Messel shale accumulated 47 +/- 2 million years ago in anaerobic waters at the bottom of a lake. Subsequent depths of burial have not exceeded 300 m, nor has the temperature of the shale exceeded 40 degrees C. Contents of organic carbon reach 25%, and preservation of molecular structures has been excellent. Sixteen different geoporphyrins, including three derived from bacteriochlorophylls of the d series and thus indicative of the existence in the lake of an anaerobic photic zone, have been isolated and identified. Here, we show that the carbon isotopic compositions of these and other biomarkers allow identification of specific sources for some materials and reconstruction of carbon flows within the lake and its sediments. The 13C content of organic matter synthesized by lacustrine primary producers can be estimated from the observed 13C content of the geoporphyrins derived from their chlorophylls. Total organic material in the shale is depleted in 13C by six parts per thousand relative to that input. This difference cannot be explained by selective loss of components enriched in 13C, nor, as shown by isotopic compositions of other biomarkers, by inputs from land plants surrounding the lake or from methanogenic bacteria.
    背景与目标: :现在,构成梅塞尔页岩的沉积物堆积在47年前-200万年前在湖底的厌氧水中。随后的埋葬深度不超过300 m,页岩温度也不超过40摄氏度。有机碳含量达到25%,并且分子结构的保存也非常出色。已分离和鉴定了十六种不同的地理卟啉,包括三种衍生自d系列细菌叶绿素的,因此指示了湖中存在厌氧性光合带。在这里,我们显示了这些和其他生物标记物的碳同位素组成,可以识别某些材料的特定来源,并可以重建湖泊及其沉积物中的碳流。由湖泊初级生产者合成的有机物的13C含量可以从观察到的源自其叶绿素的地卟啉的13C含量来估算。页岩中的总有机物质在13C中相对于该投入而言减少了千分之六。这种差异不能通过富含13 C的成分的选择性损失来解释,也不能通过其他生物标志物的同位素组成来证明,也不能通过围绕湖的陆地植物或产甲烷细菌的输入来解释。
  • 【始新世中期到早渐新世格陵兰冰川冰和泛北极海冰的证据。】 复制标题 收藏 收藏
    DOI:10.1038/s41467-018-03180-5 复制DOI
    作者列表:Tripati A,Darby D
    BACKGROUND & AIMS: :Earth's modern climate is defined by the presence of ice at both poles, but that ice is now disappearing. Therefore understanding the origin and causes of polar ice stability is more critical than ever. Here we provide novel geochemical data that constrain past dynamics of glacial ice on Greenland and Arctic sea ice. Based on accurate source determinations of individual ice-rafted Fe-oxide grains, we find evidence for episodic glaciation of distinct source regions on Greenland as far-ranging as ~68°N and ~80°N synchronous with ice-rafting from circum-Arctic sources, beginning in the middle Eocene. Glacial intervals broadly coincide with reduced CO2, with a potential threshold for glacial ice stability near ~500 p.p.m.v. The middle Eocene represents the Cenozoic onset of a dynamic cryosphere, with ice in both hemispheres during transient glacials and substantial regional climate heterogeneity. A more stable cryosphere developed at the Eocene-Oligocene transition, and is now threatened by anthropogenic emissions.
    背景与目标: :地球的现代气候是由两极都存在冰块决定的,但现在冰块正在消失。因此,了解极地冰稳定的成因和成因比以往任何时候都更为重要。在这里,我们提供了新颖的地球化学数据,这些数据限制了格陵兰岛和北极海冰上冰川冰过去的动力学。基于对单个浮冰中的Fe-氧化物颗粒的精确源确定,我们发现了格陵兰岛上不同源区域的偶发冰期作用,范围从〜68°N和〜80°N,同时还与从北极圈外的冰河漂流同步来源,始于始新世中期。冰川间隔大致与二氧化碳减少相吻合,冰川冰稳定的潜在阈值接近〜500p.p.m.v。始新世中期代表着动态冰冻圈的新生代,在短暂的冰川和实质性的区域气候异质性过程中,两个半球都有冰。在始新世-渐新世过渡期形成了一个更稳定的冰冻圈,现在受到人为排放的威胁。
  • 【来自缅甸中部庞东最新中新世的一种新类人猿。】 复制标题 收藏 收藏
    DOI:10.1006/jhev.2001.0463 复制DOI
    作者列表:Takai M,Shigehara N,Aung AK,Tun ST,Soe AN,Tsubamoto T,Thein T
    BACKGROUND & AIMS: A new genus and species of medium-sized fossil primate, Myanmarpithecus yarshensis, is described from the lastest middle Eocene sediments of Pondaung, central Myanmar (Burma). The specimens consist of right maxillary fragments with P(4)-M(3)and a left mandibular corpus with C-P(3)and M(2-3). To date, three purported anthropoids have been discovered from the Pondaung FormationPondaungia and Amphipithecus (Amphipithecidae) and Bahinia (Eosimiidae). Myanmarpithecus differs from these other Pondaung primates in having cingular hypocones on upper molars and in lacking paraconids on M(2-3). Although Myanmarpithecus resembles some utahiin omomyines in superficial aspects of the morphology of M(2-3)(i.e., mesiodistally compressed molar trigonid and enamel crenulation), the morphological analysis of upper molars and lower premolars indicates that it is neither an omomyoid nor an adapoid but is more derived than fossil prosimians (such as adapoids, omomyoids, and tarsiers) and more anthropoid-like. On the other hand, it is more primitive (prosimian-like) than early anthropoids from the late Eocene/early Oligocene of the Fayum, Egypt. Myanmarpithecus is likely to be an early, primitive anthropoid ("protoanthropoid").

    背景与目标: 从缅甸中部(缅甸)庞东最新的中新世中新世沉积物中,描述了一种中型化石灵长类动物的新属和种。标本由具有P(4)-M(3)的右上颌骨碎片和具有C-P(3)和M(2-3)的左下颌骨组成。迄今为止,已经从庞东岩层庞东岩和两栖猿(两栖纲)和Bahinia(嗜伊科)中发现了三个据称的类人动物。缅甸猿与其他这些Pondaung灵长类动物的不同之处在于,上臼齿上有齿状次圆锥,而M(2-3)上没有副圆锥形。尽管缅甸皮氏菌在M(2-3)形态的表观方面(即近中压缩的磨牙三角骨和牙釉质细齿化)类似于某些utahiin乙型肌氨酸,但上臼齿和下前臼齿的形态分析表明,它既不是阿米巴型也不是阿片类药物但比化石prosimians(如阿片类,阿片类和tarsiers)更衍生,更像类人猿。另一方面,它比来自埃及法尤姆的晚始新世/早渐新世的早期类人猿更原始(类似prosimian)。缅甸猿可能很可能是早期的原始类人猿(“ protoanthropoid”)。

  • 【为无孔胡椒属建立化石记录:Saururus tuckerae sp.。十一月(始祖科)来自中新世普林斯顿·彻特。】 复制标题 收藏 收藏
    DOI:10.3732/ajb.94.10.1642 复制DOI
    作者列表:Smith SY,Stockey RA
    BACKGROUND & AIMS: :Investigations of small permineralized flowers from the Middle Eocene Princeton Chert, British Columbia, Canada have revealed that they represent an extinct species of Saururus. Over 100 flowers and one partial inflorescence were studied, and numerous minute perianthless flowers are borne in an indeterminate raceme. Each flower is subtended by a bract, and flowers and bracts are borne at the end of a common stalk. Five stamens are basally adnate to the carpels. Pollen is frequently found in situ in the anthers. Examined under SEM and TEM, pollen grains are minute (6-11 μm), monosulcate, boat-shaped-elliptic, with punctate sculpturing and a granulate aperture membrane. The gynoecium is composed of four basally connate, lobed carpels with recurved styles and a single ovule per carpel. Flower structure and pollen are indicative of Saururaceae (Piperales), and in phylogenetic analyses using morphological characters, the fossils are sister to extant Saururus. The fossil flowers are described here as Saururus tuckerae sp. nov. These fossil specimens add to the otherwise sparse fossil record of Piperales, represent the oldest fossils of Saururaceae as well as the first North American fossil specimens of this family, and provide the first evidence of saururaceous pollen in the fossil record.
    背景与目标: :来自加拿大不列颠哥伦比亚省中新世普林斯顿切尔特的小矿化花朵的调查显示,它们代表了灭绝的蜥蜴类。研究了超过100朵花和一个局部花序,并且在一个不确定的总状花序中载有许多微小的无孔花朵。每朵花都被a片所包住,而花朵和片则紧贴在普通茎的末端。五个雄蕊基本贴生于心皮。花粉经常在花药中原位发现。在SEM和TEM下检查,花粉颗粒微细(6-11μm),单硫酸盐,船形椭圆形,具有点状雕刻和颗粒状孔膜。妇科由四个基生的,浅叶的心皮组成,具有反曲的样式,每个心皮有一个胚珠。花的结构和花粉表明了金龙属(Saururaceae)(Piperales),在使用形态学特征进行的系统发育分析中,这些化石是现存的金龙属的姐妹。化石花在这里被描述为Saururus tuckerae sp。十一月这些化石标本增加了原本稀疏的Piperales化石记录,代表了金缕梅科的最古老化石以及该家族的首批北美化石标本,并在化石记录中提供了金红宝石花粉的第一个证据。
  • 【修订来自南极半岛西摩岛的始新世南极地毯鲨(Elasmobranchii,Orectolobiformes)。】 复制标题 收藏 收藏
    DOI:10.1080/14772019.2016.1266048 复制DOI
    作者列表:Engelbrecht A,Mörs T,Reguero MA,Kriwet J
    BACKGROUND & AIMS: :Seymour Island, Antarctic Peninsula, was once called the 'Rosetta Stone' of Southern Hemisphere palaeobiology, because this small island provides the most complete and richly fossiliferous Palaeogene sequence in Antarctica. Among fossil marine vertebrate remains, chondrichthyans seemingly were dominant elements in the Eocene Antarctic fish fauna. The fossiliferous sediments on Seymour Island are from the La Meseta Formation, which was originally divided into seven stratigraphical levels, TELMs 1-7 (acronym for Tertiary Eocene La Meseta) ranging from the upper Ypresian (early Eocene) to the late Priabonian (late Eocene). Bulk sampling of unconsolidated sediments from TELMs 5 and 6, which are Ypresian (early Eocene) and Lutetian (middle Eocene) in age, respectively, yielded very rich and diverse chondrichthyan assemblages including over 40 teeth of carpet sharks representing two new taxa, Notoramphoscyllium woodwardi gen. et sp. nov. and Ceolometlaouia pannucae gen. et sp. nov. Two additional teeth from TELM 5 represent two different taxa that cannot be assigned to any specific taxon and thus are left in open nomenclature. The new material not only increases the diversity of Eocene Antarctic selachian faunas but also allows two previous orectolobiform records to be re-evaluated. Accordingly, Stegostoma cf. faciatum is synonymized with Notoramphoscyllium woodwardi gen. et sp. nov., whereas Pseudoginglymostoma cf. brevicaudatum represents a nomen dubium. The two new taxa, and probably the additional two unidentified taxa, are interpreted as permanent residents, which most likely were endemic to Antarctic waters during the Eocene and adapted to shallow and estuarine environments.
    背景与目标: :南极半岛西摩岛曾经被称为南半球古生物学的“罗塞塔石”,因为这个小岛提供了南极洲最完整,最丰富的化石古生物序列。在化石海洋脊椎动物遗骸中,软骨鱼类似乎是始新世南极鱼类动物群中的主要元素。西摩岛上的化石沉积物来自La Meseta地层,该地层最初分为七个地层,即TELM 1-7(第三纪始新世La Meseta的缩写),范围从上伊波利安世(早始新世)到后期的Priabonian(晚始新世)。 )。大量采样来自TELM 5和6的未固结沉积物,年龄分别为伊普尔前期(始新世)和鲁特田(中始新世),产生了非常丰富和多样的软骨鱼类组合,包括代表两个新类群的齿鲨的40多颗齿鲨。 gen。等十一月和Ceolometlaouia pannucae gen。等十一月来自TELM 5的另外两个牙齿代表两个不同的分类单元,它们不能分配给任何特定的分类单元,因此保留为开放式命名法。这种新材料不仅增加了始新世南极软体动物的多样性,而且还可以重新评估以前的两个地貌生物记录。相应地,Stegostomacf。面筋是Notoramphoscyllium woodwardi gen的代名词。等十一月。,而Pseudoginglymostomacf。 brevicaudatum代表nomen dubium。这两个新的分类单元,可能还有另外两个未分类的分类单元,被解释为永久居民,最有可能在始新世期间是南极水域的特有物种,并适应浅海和河口环境。
  • 【埃克费尔德埃克费尔德玛尔化石遗址的数字定年:始新世时标的校准标记。】 复制标题 收藏 收藏
    DOI:10.1007/s001140050719 复制DOI
    作者列表:Mertz DF,Swisher CC,Franzen JL,Neuffer FO,Lutz H
    BACKGROUND & AIMS: :Sediments of the Eckfeld maar (Eifel, Germany) bear a well-preserved Eocene fauna and flora. Biostratigraphically, Eckfeld corresponds to the Middle Eocene mammal reference level MP (Mammals Paleogene) 13 of the ELMA (European Land Mammal Age) Geiseltalian. In the maar crater, basalt fragments were drilled, representing explosion crater eruption products. By 40Ar/39Ar dating of the basalt, for the first time a direct numerical calibration mark for an Eocene European mammal locality has been established. The Eckfeld basalt inverse isochron date of 44.3 +/- 0.4 Ma suggests an age for the Geiseltalian/Robiacian boundary at 44 Ma and, together with the 1995 time scale of Berggren et al., a time span ranging from 49 to 44 Ma for the Geiseltalian and from 44 to 37 Ma for the Robiacian, respectively. Additional 40Ar/39Ar dating on a genetically related basalt occurrence close to the maar confirms a period of volcanism of ca. 0.6 m.y. in the Eckfeld area, matching the oldest Eocene volcanic activity of the Hocheifel volcanic field.
    背景与目标: :Eckfeld maar(德国埃菲尔)的沉积物拥有保存完好的始新世动植物群。在生物地层学上,埃克菲尔德对应于ELMA(欧洲陆地哺乳动物时代)Geiseltalian的始新世中期哺乳动物参考水平MP(哺乳动物古近纪)13。在马尔陨石坑中,钻出了玄武岩碎片,代表了爆炸陨石坑的喷发产物。通过对玄武岩进行40Ar / 39Ar测年,首次为始新世欧洲哺乳动物地区建立了直接的数字校准标记。埃克菲尔德玄武岩逆等时日期为44.3 /-0.4 Ma,表明吉塞他尔/罗比亚剖面的年龄为44 Ma,再加上1995年Berggren等人的时间尺度,盖瑟塔尔纪的时间跨度为49-44 Ma。而Robiacian则从44到37 Ma。在接近马尔的与遗传相关的玄武岩发生上,另外的40Ar / 39Ar年代测定证实了约有一个火山爆发期。 0.6 y.y.在埃克费尔德地区,与Hocheifel火山场中最古老的始新世火山活动相匹配。
  • 【印度西高止山脉南部晚古新世-早始新世赤道雨林避难所的证据。】 复制标题 收藏 收藏
    DOI:10.1007/s12038-009-0062-y 复制DOI
    作者列表:Prasad V,Farooqui A,Tripathi SK,Garg R,Thakur B
    BACKGROUND & AIMS: :Equatorial rain forests that maintain a balance between speciation and extinction are hot-spots for studies of biodiversity. Western Ghats in southern India have gained attention due to high tropical biodiversity and endemism in their southern most area. We attempted to track the affinities of the pollen fl ora of the endemic plants of Western Ghat area within the fossil palynoflora of late Palaeocene-early Eocene (approximately 55-50 Ma) sedimentary deposits of western and northeastern Indian region. The study shows striking similarity of extant pollen with twenty eight most common fossil pollen taxa of the early Palaeogene. Widespread occurrences of coal and lignite deposits during early Palaeogene provide evidence of existence of well diversified rain forest community and swampy vegetation in the coastal low lying areas all along the western and northeastern margins of the Indian subcontinent. Prevalence of excessive humid climate during this period has been seen as a result of equatorial positioning of Indian subcontinent, superimposed by a long term global warming phase (PETM and EECO) during the early Palaeogene. The study presents clear evidence that highly diversifi ed equatorial rain forest vegetation once widespread in the Indian subcontinent during early Palaeogene times, are now restricted in a small area as a refugia in the southernmost part of the Western Ghat area. High precipitation and shorter periods of dry months seem to have provided suitable environment to sustain lineages of ancient tropical vegetation in this area of Western Ghats in spite of dramatic climatic changes subsequent to the post India-Asia collision and during the Quaternary and Recent times.
    背景与目标: :在物种形成和物种灭绝之间保持平衡的赤道雨林是生物多样性研究的热点。印度南部的西高止山脉因其最南部地区的高度热带生物多样性和特有性而备受关注。我们试图追踪印度西部和东北印度地区晚新世-早始新世(约55-50 Ma)的化石古生物化石中西高止地区特有植物花粉的亲和力。研究表明现存花粉与古近代早期的28种最常见的化石花粉类群具有惊人的相似性。在古近纪早期发生的广泛的煤和褐煤沉积事件提供了证据,证明印度次大陆西部和东北边缘的沿海低洼地区存在着雨林群落分布广泛且植被茂盛的证据。由于印度次大陆的赤道定位,加上长期的全球变暖阶段(PETM和EECO)在古近纪初期,这一时期的过度潮湿气候盛行。这项研究提供了明确的证据,即高度古朴的赤道雨林植被曾经在古近代时代初期在印度次大陆广泛分布,但如今却在西高止山脉最南端的一个小区域受到限制。尽管在印度-亚洲碰撞后以及第四纪和最近时期,尽管气候发生了巨大变化,但高降水量和较短的干旱期似乎为西部高止山脉地区的古代热带植被提供了合适的环境。
  • 【使用叶片大小和植物区系解析出始新世巴塔哥尼亚古森林的澳大利亚类似物。】 复制标题 收藏 收藏
    DOI:10.3732/ajb.1500159 复制DOI
    作者列表:Merkhofer L,Wilf P,Haas MT,Kooyman RM,Sack L,Scoffoni C,Cúneo NR
    BACKGROUND & AIMS: UNLABELLED:• PREMISE OF THE STUDY:The diverse early Eocene flora from Laguna del Hunco (LH) in Patagonia, Argentina has many nearest living relatives (NLRs) in Australasia but few in South America, indicating the differential survival of an ancient, trans-Antarctic rainforest biome. To better understand this significant biogeographic pattern, we used detailed comparisons of leaf size and floristics to quantify the legacy of LH across a large network of Australian rainforest-plot assemblages.• METHODS:We applied vein scaling, a new method for estimating the original areas of fragmented leaves. We then compared leaf size and floristics at LH with living Australian assemblages and tabulated the climates of those where NLRs occur, along with additional data on climatic ranges of "ex-Australian" NLRs that survive outside of Australia.• KEY RESULTS:Vein scaling estimated areas as accurately as leaf-size classes. Applying vein scaling to fossil fragments increased the grand mean area of LH by 450 mm(2), recovering more originally large leaves. The paleoflora has a majority of microphyll leaves, comparable to leaf litter in subtropical Australian forests, which also have the greatest floristic similarity to LH. Tropical Australian assemblages also share many taxa with LH, and ex-Australian NLRs mostly inhabit cool, wet montane habitats no longer present in Australia.• CONCLUSIONS:Vein scaling is valuable for improving the resolution of fossil leaf-size distributions by including fragmented specimens. The legacy of LH is evident not only in subtropical and tropical Australia but also in tropical montane Australasia and Southeast Asia, reflecting the disparate histories of surviving Gondwanan lineages.
    背景与目标: 未贴标签:•
    研究的前提:阿根廷巴塔哥尼亚的拉古纳·德尔·洪科(LH)的始新世早期菌群种类繁多,在大洋洲有许多最近的近亲(NLR),而在南美洲则很少,这表明一个古老的南极热带雨林生物群落的生存差异。为了更好地理解这种重要的生物地理格局,我们使用了叶子大小和植物区系的详细比较,以量化了整个澳大利亚雨林地块组合网络中LH的遗留物。
    方法:我们应用了静脉缩放法,这是一种估计碎叶原始面积的新方法。然后,我们将LH的叶子大小和植物区系与澳大利亚的活体种群进行了比较,并列出了发生NLR的气候,并提供了在澳大利亚境外生存的“前澳大利亚” NLR的气候范围的其他数据。
    关键结果:静脉缩放估计的面积与叶片大小的类一样准确。对化石碎片应用静脉缩放将LH的平均面积增加了450 mm(2),恢复了更多的原始大叶片。古植物具有大部分的微叶叶子,与亚热带澳大利亚森林中的凋落物相当,它们与LH的植物区系相似性也最大。澳大利亚的热带组合还与LH共享许多类群,而前澳大利亚的NLR大多栖息在澳大利亚不再存在的凉爽湿润的山地生境中。
    结论:静脉结垢通过包括破碎的标本,对于提高化石叶片尺寸分布的分辨率非常有价值。 LH的遗产不仅在澳大利亚的亚热带和热带地区,而且在热带山地大洋洲和东南亚也很明显,这反映了冈瓦纳人血统尚存的不同历史。

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