Significance of enamel thickness in hominoid evolution

Enamel thickness has assumed unique importance in the debate about the hominid status of Ramapithecus, despite the fact that there is little agreement about the meaning of 'thick enamel' or the significance of enamel thickness for hominoid taxonomy. My aim here is to evaluate the usefulness of enamel thickness and microstructure as characteristics for determining the relationships of the later Miocene hominoids, based both on a quantitative study of enamel thickness in extant hominoids and four species of later Miocene Sivapithecus (including 'Ramapithecus') and on scanning electron microscope analysis of enamel microstructure. Four categories of enamel thickness are defined metrically here and have been related to enamel microstructure and developmental rates. Thin fast-formed (pattern 3) enamel represents the ancestral condition in hominoids; it increased developmentally to thick pattern 3 enamel in the great ape and human clade and that condition is primitively retained in Homo and in the fossil hominoid Sivapithecus (including 'Ramapithecus'). Enamel thickness has been secondarily reduced in the African apes and also, although at a different rate and extent, in the orang-utan. Thick enamel, previously the most important characteristic in arguments about the earliest hominid, does not therefore identify a hominid.     

Statistical analyses of metric data of hominoid teeth found in Yuanmou of China

Mesial-distal and buccal-lingual dimensions of 1 266 hominoid teeth found in Yuanmou of Yunnan Province during the period of 1986 and 1988 have been measured. The statistical analyses of the metric data show that the tooth sizes of Yuanmou hominoid can be divided into big and small two types, and most tooth dimensions display obvious bimodalities in both histograms and 2 dimensional plots. The coefficients of variance (CV) reveal that the CVs of Yuanmou hominoid tooth sizes are within or close to the CV ranges ofLufengpithecus and extant great apes. The comparisons of tooth sizes and their proportions indicate that Yuanmou hominoids have close affinities with Lefeng and Kaiyuan hominoids, and have obvious differences with Gorilla, Chimpanzee and Orangutan. The authors believe that the hominoid fossils found in Yuanmou in the past 10 years represent a single species with highly sexual dimorphism in morphology and this species may have a close evolutionary relationship with the hominoids found in Kaiyuan and Lufeng.     

New Sivapithecus humeri from Pakistan and the relationship of Sivapithecus and Pongo

New humeri of two species of the Miocene hominoid Sivapithecus are described from near Chinji in Pakistan from between approximately 9 and 11 Myr ago. Sivapithecus, a middle and late Miocene hominoid from Turkey and Indo-Pakistan, is overall unlike any living hominoid, although facial-palatal similarities to the extant orangoutan, Pongo, have been used to support a hypothesis of close relationship. Living hominoids have postcranial similarities assumed to be shared derived, among them features of the proximal humerus. However, the new Sivapithecus proximal humeri differ from those of living hominoids, supporting an alternative hypothesis in which Sivapithecus and Pongo are not closely related. It is not clear how to choose between these incompatible hypotheses.     

Dual origin of tribosphenic mammals

Marsupials, placentals and their close therian relatives possess complex (tribosphenic) molars that are capable of versatile occlusal functions. This functional complex is widely thought to be a key to the early diversification and evolutionary success of extant therians and their close relatives (tribosphenidans). Long thought to have arisen on northern continents, tribosphenic mammals have recently been reported from southern landmasses. The great age and advanced morphology of these new mammals has led to the alternative suggestion of a Gondwanan origin for the group. Implicit in both biogeographic hypotheses is the assumption that tribosphenic molars evolved only once in mammalian evolutionary history. Phylogenetic and morphometric analyses including these newly discovered taxa suggest a different interpretation: that mammals with tribosphenic molars are not monophyletic. Tribosphenic molars evolved independently in two ancient (holotherian) mammalian groups with different geographic distributions during the Jurassic/Early Cretaceous: an australosphenidan clade endemic to Gondwanan landmasses, survived by extant monotremes; and a boreosphenidan clade of Laurasian continents, including extant marsupials, placentals and their relatives.     

Fossil that fills a critical gap in avian evolution

Despite the discoveries of well-preserved Mesozoic birds, a key part of avian evolution, close to the radiation of all living birds (Aves), remains poorly represented. Here we report on a new taxon from the Late Cretaceous locality of Ukhaa Tolgod, Mongolia, that offers insight into this critically unsampled period. Apsaravis and the controversial alvarezsaurids are the only avialan taxa known from the continental deposits at Ukhaa Tolgod, which have produced hundreds of fossil mammals, lizards and other small dinosaurs. The new taxon, Apsaravis ukhaana, is the best-preserved specimen of a Mesozoic ornithurine bird discovered in over a century. It provides data important for assessing morphological evolution across Avialae, with implications for, first, the monophyly of Enantiornithes and Sauriurae; second, the proposition that the Mesozoic sister taxa of extant birds, as part of an 'ecological bottleneck', inhabited exclusively near-shore and marine environments; and third, the evolution of flight after its origin.     

中国连珠藻属Sirodotia(红藻门)的分支分类研究

以连珠藻属Sirodotia Keylin的7个分类单位加上外类群作为研究对象,选取10个性状作为数量指标,得到10×7的数值矩阵,以分支分类学的方法对连珠藻属的系统发育过程进行分析.采用最大同步法、综合分析法、演化极端结合法及最小平行进化法进行分支分析,其中,最大同步法、综合分析法和演化极端结合法三种方法的运算结果完全一致,分支图最大步长为36,最小步长为11,实际步长为14,简约系数为0.12.在连珠藻属中,以黄山连珠藻S.huangshanensis最为原始,瑞典连珠藻S.suecica和细连珠藻S.tenuissima则较为进化.     

A new troodontid dinosaur from China with avian-like sleeping posture

Discovering evidence of behaviour in fossilized vertebrates is rare. Even rarer is evidence of behaviour in non-avialan dinosaurs that directly relates to stereotypical behaviour seen in extant birds (avians) and not previously predicted in non-avialan dinosaurs. Here we report the discovery of a new troodontid taxon from the Early Cretaceous Yixian Formation of western Liaoning, China. Numerous other three-dimensionally preserved vertebrate fossils have been recovered recently at this locality, including some specimens preserving behavioural information. The new troodontid preserves several features that have been implicated in avialan origins. Notably, the specimen is preserved in the stereotypical sleeping or resting posture found in extant Aves. Evidence of this behaviour outside of the crown group Aves further demonstrates that many bird features occurred early in dinosaurian evolution.     

A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago

Small Late Jurassic theropod dinosaurs are rare worldwide. In Europe these carnivorous dinosaurs are represented primarily by only two skeletons of Compsognathus, neither of which is well preserved. Here we describe a small new theropod dinosaur from the Late Jurassic period of Schamhaupten in southern Germany. Being exquisitely preserved and complete from the snout to the distal third of the tail, the new fossil is the best-preserved predatory, non-avian dinosaur in Europe. It possesses a suite of characters that support its identification as a basal coelurosaur. A cladistic analysis indicates that the new taxon is closer to maniraptorans than to tyrannosauroids, grouping it with taxa often considered to be compsognathids. Large portions of integument are preserved along its tail. The absence of feathers or feather-like structures in a fossil phylogenetically nested within feathered theropods indicates that the evolution of these integumentary structures might be more complex than previously thought.     

New frog family from India reveals an ancient biogeographical link with the Seychelles

About 96% of the more than 4,800 living anuran species belong to the Neobatrachia or advanced frogs. Because of the extremely poor representation of these animals in the Mesozoic fossil record, hypotheses on their early evolution have to rely largely on extant taxa. Here we report the discovery of a burrowing frog from India that is noticeably distinct from known taxa in all anuran families. Phylogenetic analyses of 2.8 kilobases of mitochondrial and nuclear DNA unambiguously designate this frog as the sister taxon of Sooglossidae, a family exclusively occurring on two granitic islands of the Seychelles archipelago. Furthermore, molecular clock analyses uncover the branch leading to both taxa as an ancient split in the crown-group Neobatrachia. Our discovery discloses a lineage that may have been more diverse on Indo-Madagascar in the Cretaceous period, but now only comprises four species on the Seychelles and a sole survivor in India. Because of its very distinct morphology and an inferred origin that is earlier than several neobatrachian families, we recognize this frog as a new family.     

A new orang-utan relative from the Late Miocene of Thailand

The fossil record of the living great apes is poor. New fossils from undocumented areas, particularly the equatorial forested habitats of extant hominoids, are therefore crucial for understanding their origins and evolution. Two main competing hypotheses have been proposed for orang-utan origins: dental similarities support an origin from Lufengpithecus, a South Chinese and Thai Middle Miocene hominoid; facial and palatal similarities support an origin from Sivapithecus, a Miocene hominoid from the Siwaliks of Indo-Pakistan. However, materials other than teeth and faces do not support these hypotheses. Here we describe the lower jaw of a new hominoid from the Late Miocene of Thailand, Khoratpithecus piriyai gen. et sp. nov., which shares unique derived characters with orang-utans and supports a hypothesis of closer relationships with orang-utans than other known Miocene hominoids. It can therefore be considered as the closest known relative of orang-utans. Ancestors of this great ape were therefore evolving in Thailand under tropical conditions similar to those of today, in contrast with Southern China and Pakistan, where temperate or more seasonal climates appeared during the Late Miocene.     

串珠藻目(红藻门)基于形态学证据的系统发育分析

以串珠藻目的16个分类单位加上外类群作为研究对象,选取18个性状作为研究基础,得到18×17的数值矩阵,以分支分类学的方法对串珠藻目的系统发育过程进行分析.采用4种方法进行分支分析,其中以最大同步法的运算结果最为合理,分支图最大步长为269,最小步长为35,实际步长为47,简约系数为0.0513.在串珠藻目中,以红索藻科最为原始,它向两个方向演化,其中一大支随着受精丝的明显膨大,演化出串珠藻科;另一大支则有更多的形态特征发生变化,配子体中出现假薄壁组织,中轴节处产生有定数的分枝,出现发达的外皮层,精子囊以精子囊群的方式成块状或带状出现,果孢子体生于外皮层内部,演化出鱼子菜科和裸管藻科.在串珠藻科中,以串珠藻属的串珠藻组较为原始,而假枝藻属和托氏藻属则较为进化.     

Primate eta-globin DNA sequences and man's place among the great apes

Molecular studies indicate that chimpanzee and gorilla are the closest relatives of man (refs 1-7 and refs therein). The small molecular distances found point to late ancestral separations, with the most recent being between chimpanzee and man, as judged by DNA hybridization. Kluge and Schwartz contest these conclusions: morphological characters group a chimpanzee-gorilla clade with the Asian ape orang-utan in Kluge's cladistic study and with an orang-utan-human clade in Schwartz's study. Clearly, extensive sequencing of nuclear DNA is needed to resolve by cladistic analysis the branching order within Hominoidea. Towards this goal, we are sequencing orthologues of the primate psi eta-globin locus. Here, we compare the newly completed sequences of orang-utan and rhesus monkey with human, chimpanzee, gorilla, owl monkey, lemur and goat orthologues. Our findings substantially increase the evidence indicative of a human-chimpanzee-gorilla clade with ancestral separations around 8 to 6 Myr ago. We also verify that neutral hominoid DNA evolved at markedly retarded rates.     

Molecular phylogenetics and the origins of placental mammals

The precise hierarchy of ancient divergence events that led to the present assemblage of modern placental mammals has been an area of controversy among morphologists, palaeontologists and molecular evolutionists. Here we address the potential weaknesses of limited character and taxon sampling in a comprehensive molecular phylogenetic analysis of 64 species sampled across all extant orders of placental mammals. We examined sequence variation in 18 homologous gene segments (including nearly 10,000 base pairs) that were selected for maximal phylogenetic informativeness in resolving the hierarchy of early mammalian divergence. Phylogenetic analyses identify four primary superordinal clades: (I) Afrotheria (elephants, manatees, hyraxes, tenrecs, aardvark and elephant shrews); (II) Xenarthra (sloths, anteaters and armadillos); (III) Glires (rodents and lagomorphs), as a sister taxon to primates, flying lemurs and tree shrews; and (IV) the remaining orders of placental mammals (cetaceans, artiodactyls, perissodactyls, carnivores, pangolins, bats and core insectivores). Our results provide new insight into the pattern of the early placental mammal radiation.     

Fossil Orangutan-like hominoid teeth from Late Pleistocene human site of Mulanshan cave in Chongzuo of Guangxi and implications on taxonomy and evolution of orangutan

Fossil records indicate orangutan-like hominoids have been widely distributed in south China during Pleistocene, although currently only surviving in the tropical forests of Kalimantan and Sumatra in Indonesia. This paper describes the recently discovered hominoid fossil teeth from human site of Mulanshan cave in Chongzuo of Guangxi, whose geological age is the Late Pleistocene, about 11000 yeas age based on associated mammal fauna and U-series dating. Compared with those of modern and subfossil orangutans from Indonesia, other fossil great apes from China, the hominoid teeth from Mulanshan cave are orangutan-like, but show somehow different from Indonesia＇s orangutans, the average sizes of cheek teeth larger and occlusal enamel wrinkles less and simpler. They are classified temporarily as the subspecies of Pongo pygmaeus weidenreichi. Concerning the variations of morphological features and dental sizes of orangutan-like teeth from southern China and neighboring northern Vietnam, different subspecies or species or genus possibly, but the key evidence is necessary to be identified.     

Geology and palaeontology of the Late Miocene Middle Awash valley, Afar rift, Ethiopia.

The Middle Awash study area of Ethiopia's Afar rift has yielded abundant vertebrate fossils (approximately 10,000), including several hominid taxa. The study area contains a long sedimentary record spanning Late Miocene (5.3-11.2 Myr ago) to Holocene times. Exposed in a unique tectonic and volcanic transition zone between the main Ethiopian rift (MER) and the Afar rift, sediments along the western Afar rift margin in the Middle Awash provide a unique window on the Late Miocene of Ethiopia. These deposits have now yielded the earliest hominids, described in an accompanying paper and dated here to between 5.54 and 5.77 Myr. These geological and palaeobiological data from the Middle Awash provide fresh perspectives on hominid origins and early evolution. Here we show that these earliest hominids derive from relatively wet and wooded environments that were modulated by tectonic, volcanic, climatic and geomorphic processes. A similar wooded habitat also has been suggested for the 6.0 Myr hominoid fossils recently recovered from Lukeino, Kenya. These findings require fundamental reassessment of models that invoke a significant role for global climatic change and/or savannah habitat in the origin of hominids.     

Preserving the evolutionary potential of floras in biodiversity hotspots

One of the biggest challenges for conservation biology is to provide conservation planners with ways to prioritize effort. Much attention has been focused on biodiversity hotspots. However, the conservation of evolutionary process is now also acknowledged as a priority in the face of global change. Phylogenetic diversity (PD) is a biodiversity index that measures the length of evolutionary pathways that connect a given set of taxa. PD therefore identifies sets of taxa that maximize the accumulation of 'feature diversity'. Recent studies, however, concluded that taxon richness is a good surrogate for PD. Here we show taxon richness to be decoupled from PD, using a biome-wide phylogenetic analysis of the flora of an undisputed biodiversity hotspot--the Cape of South Africa. We demonstrate that this decoupling has real-world importance for conservation planning. Finally, using a database of medicinal and economic plant use, we demonstrate that PD protection is the best strategy for preserving feature diversity in the Cape. We should be able to use PD to identify those key regions that maximize future options, both for the continuing evolution of life on Earth and for the benefit of society.     

A primitive therizinosauroid dinosaur from the Early Cretaceous of Utah

Therizinosauroids are an enigmatic group of dinosaurs known mostly from the Cretaceous period of Asia, whose derived members are characterized by elongate necks, laterally expanded pelves, small, leaf-shaped teeth, edentulous rostra and mandibular symphyses that probably bore keratinized beaks. Although more than a dozen therizinosauroid taxa are known, their relationships within Dinosauria have remained controversial because of fragmentary remains and an unusual suite of characters. The recently discovered 'feathered' therizinosauroid Beipiaosaurus from the Early Cretaceous of China helped to clarify the theropod affinities of the group. However, Beipiaosaurus is also poorly represented. Here we describe a new, primitive therizinosauroid from an extensive paucispecific bonebed at the base of the Cedar Mountain Formation (Early Cretaceous) of east-central Utah. This new taxon represents the most complete and most basal therizinosauroid yet discovered. Phylogenetic analysis of coelurosaurian theropods incorporating this taxon places it at the base of the clade Therizinosauroiden, indicating that this species documents the earliest known stage in the poorly understood transition from carnivory to herbivory within Therizinosauroidea. The taxon provides the first documentation, to our knowledge, of therizinosauroids in North America during the Early Cretaceous.     

外类群对构建基因树的影响

以金缕梅科枫香亚科和睡莲目的分子数据为例，初步探讨了不同的单一外类群、复合外类群和随机外类群对构建基因树的影响．基因树比较的结果表明：与内类群亲缘关系较近的单一外类群能反映较多信息，而复合外类群与其中１个或多个单一外类群的结果相同，应用随机外类群则可获得一个粗略的分支关系．     

Late Cretaceous relatives of rabbits, rodents, and other extant eutherian mammals.

Extant eutherian mammals and their most recent common ancestor constitute the crown group Placentalia. This taxon, plus all extinct taxa that share a more recent common ancestor with placentals than they do with Metatheria (including marsupials), constitute Eutheria. The oldest well documented eutherian-dominated fauna in the world is Dzharakuduk, Uzbekistan. Among eutherians that it yields is Kulbeckia, an 85-90-Myr-old member of Zalambdalestidae (a family of Late Cretaceous Asian eutherians). This extends Zalambdalestidae back by some 10 million years from sites in the Gobi Desert, Mongolia. A phylogenetic analysis of well described Late Cretaceous eutherians strongly supports Zalambdalestidae, less strongly supports 'Zhelestidae' (a Late Cretaceous clade related to Tertiary ungulates), but does not support Asioryctitheria (a group of Late Cretaceous Asian eutherians). A second analysis incorporating placentals from clades that include rodents (Tribosphenomys), lagomorphs (Mimotona) and archaic ungulates (Protungulatum and Oxyprimus) strongly supports Zalambdalestidae in a clade with Glires (rabbits, rodents and extinct relatives) and less strongly 'Zhelestidae' within a clade that includes archaic ungulates ('condylarths'). This argues that some Late Cretaceous eutherians belong within the crown group Placentalia. The ages of these taxa are in line with molecularly based estimates of 64-104 Myr ago (median 84 Myr ago) for the superordinal diversification of some placentals, but provide no support for a Late Cretaceous diversification of extant placental orders.     

河北省大帽藓科植物的分类和分布

根据对河北省大帽藓植物进行了整理研究,现知该地区有本科植物７种,其中,中华大帽藓为最近在河北省发现的一个新种,西藏大帽藓、剑叶大帽藓为河北省新记录种。简要概述了每种植物的识别特征、生境和地理分布,并根据标本编制了河北省大帽藓属植物分种检索表。