首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Tinamous are volant terrestrial birds, endemic to the Neotropics. Here, an inclusive phenotype‐based phylogenetic study of the interrelationships among all extinct and living species of tinamous is conducted. In this cladistic analysis, results are compared between main character subsets and with previous molecular studies. Special attention is paid to character definition and scoring of integumentary and behavioural characters: transformation costs are applied to analyse egg coloration and plumage characters—on the basis of pigment composition and overlap of pigmentation patterns respectively—in the context of generalized (Sankoff) parsimony. Cladistic analysis recovers the traditional subdivision between those tinamous specialized for open areas (Nothurinae) and those inhabiting forested environments (Tinaminae) and support the monophyly of recognized genera. The present study demonstrates that morphological analysis yields highly congruent results when compared with previous molecular studies; thus, it provides morphological synapomorphies for clades that have been proposed by these molecular analyses. The placement of the fossil species within the open‐area (Nothurinae) and the forest‐dwelling (Tinaminae) tinamous is also consistent with the palaeoenvironmental conditions inferred from the associated flora and fauna.  相似文献   

2.
The Miocene Randeck Maar (southwestern Germany) is one of the only sites with abundant material of fossil honey bees. The fauna has been the focus of much scrutiny by early authors who recognized multiple species or subspecies within the fauna. The history of work on the Randeck Maar is briefly reviewed and these fossils placed into context with other Tertiary and living species of the genus Apis Linnaeus (Apinae: Apini). Previously unrecorded specimens from Randeck Maar were compared with earlier series in an attempt to evaluate the observed variation. A morphometric analysis of forewing venation angles across representative Recent and Tertiary species of Apis as well as various non-Apini controls was undertaken to evaluate the distribution of variation in fossil honey bees. The resulting dendrogram shows considerable variation concerning the wing venation of Miocene Apini, but intergradation of other morphological characters reveals no clear pattern of separate species. This suggests that a single, highly variable species was present in Europe during the Miocene. The pattern also supports the notion that the multiple species and subspecies proposed by earlier authors for the Randeck Maar honey bee fauna are not valid, and all are accordingly recognized as Apis armbrusteri Zeuner.  相似文献   

3.
The earliest record of fossil apes outside Africa is in the latest early Miocene of Turkey and eastern Europe. There were at least 2, and perhaps 4, species of ape, which were found associated with subtropical mixed environments of forest and more open woodland. Postcranial morphology is similar to that of early Miocene primates and indicates mainly generalized arboreal quadrupedal behaviours similar to those of less specialized New World monkeys such as Cebus. Robust jaws and thick enamelled teeth indicate a hard fruit diet. The 2 best known species of fossil ape are known from the site of Pa?alar in Turkey. They have almost identical molar and jaw morphology. Molar morphology is also similar to that of specimens from Germany and Slovakia, but there are significant differences in the anterior teeth of the 2 Pa?alar species. The more common species, Griphopithecus alpani, shares mainly primitive characters with early and middle Miocene apes in Africa, and it is most similar phenetically to Equatorius africanus from Maboko Island and Kipsaramon. The second species is assigned to a new species of Kenyapithecus, an African genus from Fort Ternan in Kenya, on the basis of a number of shared derived characters of the anterior dentition, and it is considered likely that there is a phylogenetic link between them. The African sites all date from the middle Miocene, similar in age to the Turkish and European ones, and the earliest emigration of apes from Africa coincides with the closure of the Tethys Sea preceding the Langhian transgression. Environments indicated for the African sites are mixtures of seasonal woodlands with some forest vegetation. The postcrania of both African taxa again indicate generalized arboreal adaptation but lacking specialized arboreal function. This middle Miocene radiation of both African and non-African apes was preceded by a radiation of arboreal catarrhine primates in the early Miocene, among which were the earliest apes. The earliest Miocene apes in the genus Proconsul and Rangwapithecus were arboreal, and because of their association with the fruits of evergreen rain forest plants at Mfwangano Island, it would appear that they were forest adapted, i.e. were living in multi-storied evergreen forest. The same or similar species of the same genera from Rusinga Island, together with other genera such as Nyanzapithecus and the small ape Limnopithecus, were associated with plants and animals indicating seasonal woodland environments, probably with gallery forest forming corridors alongside rivers. While the stem ancestors of the Hominoidea were almost certainly forest adapted, the evidence of environments associated with apes in the later part of the early Miocene and the middle Miocene of East Africa indicates more seasonal woodlands, similar to those reconstructed for the middle Miocene of Pa?alar in Turkey. This environmental shift was probably a requisite for the successful emigration of apes out of Africa and made possible later movement between the continents for much of the middle Miocene, including possible re-entry of at least one ape lineage back into Africa.  相似文献   

4.
Aim This study aims to document the floristic changes that occurred in Iceland between 15 and 6 Ma and to establish the dispersal mechanisms for the plant taxa encountered. Using changing patterns of dispersal, two factors controlling floristic changes are tested. Possible factors are (1) climate change, and (2) the changing biogeography of Iceland over the time interval studied; that is, the presence or absence of a Miocene North Atlantic Land Bridge. Location The North Atlantic. Methods Species lists of fossil plants from Iceland in the time period 15 to 6 Ma were compiled using published data and new data. Closest living analogues were used to establish dispersal properties for the fossil taxa. Dispersal mechanisms of fossil plants were then used to reconstruct how Iceland was colonized during various periods. Results Miocene floras of Iceland (15–6 Ma) show relatively high floristic turnover from the oldest floras towards the youngest; and few taxa from the oldest floras persist in the younger floras. The frequencies of the various dispersal mechanisms seen in the 15‐Ma floras are quite different from those recorded in the 6‐Ma floras, and there is a gradual change in the prevailing mode of dispersal from short‐distance anemochory and dyschory to long‐distance anemochory. Two mechanisms can be used to explain changing floral composition: (1) climate change, and (2) the interaction between the dispersal mechanisms of plants and the increasing isolation of proto‐Iceland during the Miocene. Main conclusions Dispersal mechanisms can be used to extract palaeogeographic signals from fossil floras. The composition of floras and dispersal mechanisms indicate that Iceland was connected both to Greenland and to Europe in the early Middle Miocene, allowing transcontinental migration. The change in prevalence of dispersal modes from 15 to 6 Ma appears to reflect the break‐up of a land bridge and the increasing isolation of Iceland after 12 Ma. Concurrent gradual cooling and isolation caused changes in species composition. Specifically, the widening of the North Atlantic Ocean prevented taxa with limited dispersal capability from colonizing Iceland, while climate cooling led to the extinction of thermophilous taxa.  相似文献   

5.
Understanding the history that underlies patterns of species richness across the Tree of Life requires an investigation of the mechanisms that not only generate young species‐rich clades, but also those that maintain species‐poor lineages over long stretches of evolutionary time. However, diversification dynamics that underlie ancient species‐poor lineages are often hidden due to a lack of fossil evidence. Using information from the fossil record and time calibrated molecular phylogenies, we investigate the history of lineage diversification in Polypteridae, which is the sister lineage of all other ray‐finned fishes (Actinopterygii). Despite originating at least 390 million years (Myr) ago, molecular timetrees support a Neogene origin for the living polypterid species. Our analyses demonstrate polypterids are exceptionally species depauperate with a stem lineage duration that exceeds 380 million years (Ma) and is significantly longer than the stem lineage durations observed in other ray‐finned fish lineages. Analyses of the fossil record show an early Late Cretaceous (100.5–83.6 Ma) peak in polypterid genus richness, followed by 60 Ma of low richness. The Neogene species radiation and evidence for high‐diversity intervals in the geological past suggest a “boom and bust” pattern of diversification that contrasts with common perceptions of relative evolutionary stasis in so‐called “living fossils.”  相似文献   

6.
The evolutionary history of the living hominoids has remained elusive despite years of exploration and the discovery of numerous Miocene fossil ape species. Part of the difficulty can be attributed to the changing nature of our views about the course of hominoid evolution. In the 1950s and 1960s, individual Miocene taxa were commonly viewed as the direct ancestors of specific living ape species, suggesting an early divergence of the modern lineages.1–5 However, in most cases, the Miocene forms were essentially “dental apes,” resembling extant species in dental and a few cranial features, but possessing more primitive postcranial features that suggested arboreal quadrupedalism rather than suspensory habits. With the introduction of molecular methods of phylogenetic reconstruction and the increasing use of cladistic analysis, it has become apparent that the radiation leading to the modern hominoids was somewhat more recent than had been believed, and that most of the Miocene hominoid species had little to do with the evolutionary history of the living apes. © 1998 Wiley-Liss, Inc.  相似文献   

7.
Cassini, G.H., Mendoza, M., Vizcaíno, S.F. & Bargo, M.S. 2011: Inferring habitat and feeding behaviour of early Miocene notoungulates from Patagonia. Lethaia, Vol. 44, pp. 153–165. Notoungulates, native fossil mammals of South America, have been usually studied from a taxonomic point of view, whereas their palaeobiology has been largely neglected. For example, morpho‐functional or eco‐morphological approaches have not been rigorously applied to the masticatory apparatus to propose hypothesis on dietary habits. In this study, we generate inferences about habitat and feeding preferences in five Santacrucian genera of notoungulates of the orders Typotheria and Toxodontia using novel computer techniques of knowledge discovery. The Santacrucian (Santa Cruz Formation, late‐early Miocene) fauna is particularly appropriate for this kind of studies due to its taxonomic richness, diversity, amount of specimens recorded and the quality of preservation. Over 100 extant species of ungulates, distributed among 13 families of artiodactyls and perissodactyls, were used as reference samples to reveal the relationships between craniodental morphology and ecological patterns. The results suggest that all Santacrucian notoungulates present morphologies characteristic of open habitats’ extant ungulates. Although the Toxodontia exhibits the same morphological pattern of living mixed‐feeders and grazers, the Typotheria shows exaggerated traits of specialized grazer ungulates. □Craniodental morphology, ecomorphology, fossil ungulates, knowledge discovery, South America.  相似文献   

8.
Caldesia, a genus of aquatic monocotyledons, is represented by four living species, which are widely distributed in the temperate and tropical Old World. The genus has an extensive Oligocene through Pleistocene fossil record in Eurasia. We survey the morphology of the extant and fossil fruits of the Alismataceae, and provide a detailed review of the morphology and anatomy of living and fossil Caldesia fruits. The latter exhibit substantial similarity, making the recognition of separate species on the basis of fruit morphology difficult. We erect the new species Caldesia brandoniana from the Early Miocene Brandon Lignite of Vermont primarily on the basis of its geographic isolation; careful revision of all fossil fruiting material of Caldesia might require placement of the Brandon specimens in a more inclusive form species. Together with leaves of Caldesia from the Miocene Clarkia flora of Idaho, this occurrence indicates that Caldesia was in the New World as recently as the Early Miocene.  相似文献   

9.
在晚新生代大型食肉目动物中,鬣狗科动物地史分布广、种类和数量多,在中国出现于中中新世至更新世晚期的地层中。形态功能学家将鬣狗科的60多个化石种分为似豺、似狼和似灵猫等生态类群,这些生态类群和现生仅存的3个食骨和1个食虫类群形成鲜明的对比。生态形态学是基于生物形态与生态环境的密切关系研究不同物种形态所代表的生态位的一种方法;研究者依靠化石鬣狗类与现生种类牙齿和头骨整体形态的相似度进行了生态形态(ecomorphology)的分类,但尚未对这些已定的生态形态进行过多变量的头骨形状分析。本文拟采用平面几何形态测量学的方法对晚中新世临夏盆地的鬣狗类进行研究,并探讨以头骨形状划分其生态形态类型的可行性。几何形态测量法是以生物形态的轮廓作为数据的计算方法,虽然目前尚未被国内古生物研究者广泛采用,但自20世纪30年代多变量统计学的理论成熟以来,这一方法的理论基础和软件算法在国外得到迅速发展,至今已成为近代生物学(neontology)和古生物学形态研究领域的一个常用工具。三维几何形态测量分析也因为三维激光扫描仪的普及而变得更简单和直观。然而,化石标本由于埋藏和保存的关系通常会出现变形或残缺不全,使目前几何形态测量方法在古生物学的应用仍主要以平面数据分析为主。平面数据采集的第一步是从与标本某一平面相垂直的角度拍摄数码照片;虽然拍摄平面的选择通常由研究者自定,但一般会选择待研究类群形状变异最具代表性的一面(如,鱼类一般选取侧视)。第二步是形态的数字化,即使用某一种形态测量软件来标出地标点(landmarks;或称界标点、标志点、标点)。地标点的选择对于分析的结果有直接而且重要的影响,一般会选择Bookstein分类中的I型或II型作为地标点的标准。这两种地标点的共同点是可以从解剖学特征上准确地在每一个标本上找到,而无不明确或复现困难的可能性。数字化后的数据在软件中用数学算法叠加起来(superimposition,或称叠合,重叠),以去除原始图片数据中标本位置、角度及其他与几何形态无关的冗余信息。所有的数字化数据叠加起来后,利用软件计算所有标本之间的几何距离。现在常用的软件中都会以平均几何形状作为中心,而且利用类似主成分分析(principal components analysis)的多变量计算来呈现相对扭曲(或称相对反卷)轴(relative warp axis),后者即是可以用来把形态差异视觉化的多变量数据。这些数据可以用平面坐标图来看不同形态的空间分布,也可以用所谓的薄板样条曲线图(thin-plate spline grid)来表示相对形态上的变化。相对扭曲轴所代表的形状数据还经常被拿来与代表几何物体大小的距心值(或称重心距离,centroid size)做回归曲线分析,以便发现种群中某些形态的异速生长模式(allometry)。本文采用几何形态测量的方法对产自和政地区的鬣狗科Hyaenictitherium,Ictitherium,Adcrocuta和旁鬣狗科Dinocrocuta的材料进行研究,分析了这4个属保存完好的头骨标本的侧面形态。与东非大草原现生食肉动物的头骨整体形态分布的比较和分析表明,和政的鼬鬣狗(Ictitherium)和鬣型鼬鬣狗(Hyaenictitherium)的头骨形状分布介于现生斑鬣狗(Crocuta crocuta)、犬科猎狗(Lycaon pictus)和金豺(Canis aureus)之间,为二者似豺生态形态的解释提供了几何形态测量证据。再者,上述两属化石鬣狗的形状分布与现生斑鬣狗的幼年个体形状重叠,表明现生斑鬣狗头骨的发育机制可能是在鼬鬣狗祖先类型的异速生长规律基础上的持续发育,进而演化出现有的粗壮形态。此外,巨鬣狗(Dinocrocuta)和副鬣狗(Adcrocuta)的头骨形状与现生的斑鬣狗在几何形态测量空间内有普遍重叠的现象,指示了这些异时出现的种类具有相似的生态形态,因而可能占据相近的生态位。结果还显示巨鬣狗和斑鬣狗的幼年个体形状相近,以及两者从幼年到成年发育的形状变化过程也具有相似的规律。因而,巨鬣狗和斑鬣狗之间的趋同演化不仅表现在成年头骨的粗壮程度上,而且在幼年发育模式中也存在平行演化现象。现生发育学与行为生态学已经证实,相对其他大型食肉动物,现生斑鬣狗发育粗壮头骨形态的机制不是以增速生长,而是以延长发育期来实现的。由此推断,巨鬣狗的发育期有可能和现生鬣狗相当(35个月),也可能由于具有相对粗壮和巨大的头骨形态,其发育期会延长些。当然,这个新解释仍需要更多的化石数据和发育研究来证实。  相似文献   

10.
As the closest living sister group of anthropoids, tarsiers (Family Tarsiidae) are an important group in primate evolution. However, their fossil record is poor: only four species have been described, two from the Eocene of China and two from the Miocene of Thailand. All are from outside the range of the living species, which occur only on islands off Southeast Asia. Here, we describe a new fossil tarsier from Pakistan, a significant range extension. This record consists of two lower molars, an upper molar, and a lower premolar found in the Miocene Manchar Formation (∼18–16 Ma [millions of years ago]) of Sindh Province, southern Pakistan. The Pakistani tarsier is morphologically distinct from all living and fossil tarsiers, but most similar to the middle Miocene Thai species Tarsius thailandicus. Though living tarsiers have traditionally been classified in a single genus, a recent revision proposed a division into three genera, which is strongly supported by molecular data. The Pakistani species is not referable to any of these genera, and we create for it and T. thailandicus a new tarsiid genus. This discovery broadens our understanding of the geographic range and morphological diversity of Miocene tarsiers and helps to put the living tarsiers into their evolutionary context.  相似文献   

11.
Recent paleontological collections at the middle Miocene locality of Maboko Island in Kenya, dated at 15-16 million years, have yielded numerous new specimens belonging to at least five species of fossil anthropoids. The most common species of ape at the site, a medium-sized primate with a very distinctive dental morphology, clearly represents a previously undescribed taxon. When compared with other Miocene anthropoids from East Africa, it has its closest affinities with the poorly known species Rangwapithecus vancouveringi from the early Miocene locality of Rusinga Island. The species from Maboko Island is described here as belonging to a new genus of fossil anthropoid, to which "Rangwapithecus" vancouveringi is also referred. The new genus has a highly distinctive suite of derived characters of its molars and premolars, which it shares with Oreopithecus bambolii from the late Miocene of Europe. These synapomorphies indicate a close phyletic relationship between the East African species and Oreopithecus and form the basis for the inclusion of these taxa in a single family, the Oreopithecidae Schwalbe, 1915. In many respects, however, the East African forms are more conservative than Oreopithecus, and in a general sense they can be regarded as an intermediate grade between Oreopithecus and the more generalized early Miocene catarrhines, the proconsuloids. There is, therefore, good fossil evidence to indicate that the origins of the Oreopithecidae can be traced back to the early Miocene of Africa.  相似文献   

12.
《Journal of morphology》2017,278(2):182-202
Antlers are unique appendages. They are shed and rebuilt at intervals, and are synapomorphic for all living Cervidae (except for the Chinese water deer, Hydropotes inermis , in which they have presumably been lost). The antlerogenic process is controlled by a complex interaction of fluctuating levels of several hormones, most importantly testosterone. The oldest antler remains are recorded from the early Miocene; these have been interpreted as non‐deciduous appendages because of supposed permanent skin coverage and the lack of a burr (a well‐developed osseous protuberance around the base of the antler, which is always present in extant cervids). The aim of this study is to test the hypothesis that antler shedding was possible in these early Miocene cervids. Antlers of all extant and eight Miocene cervid genera, including burr‐less antler fragments of the earliest cervids Procervulus , Ligeromeryx , and Lagomeryx were studied. An extensive comparative morphological analysis of external features of the antler, and of the abscission area and the base of the antler in particular, was undertaken. The results indicate that a regular, porous, and rugose abscission surface at the proximal end of the antler indicates antler shedding in both living and fossil cervids. The antler shedding mechanism must therefore have already been present in all early/mid Miocene cervid genera included in this study. On this basis, it is suggested that the presence of a burr is not prerequisite in order to shed antlers, that the presence of perpetual antlers has not yet been verified, and that the process of shedding and regeneration developed with the first appearance of these organs. This insight is particularly important for the systematic classification of early Miocene species as Cervidae, because the absence of the antler shedding and rebuilding mechanism would exclude them from the taxon Cervidae and from any relationship with extant cervids. J. Morphol. 278:182–202, 2017. © 2016 Wiley Periodicals,Inc.  相似文献   

13.
Bandicoots (Peramelemorphia) are a major order of australidelphian marsupials, which despite a fossil record spanning at least the past 25 million years and a pandemic Australasian range, remain poorly understood in terms of their evolutionary relationships. Many living peramelemorphians are critically endangered, making this group an important focus for biological and conservation research. To establish a phylogenetic framework for the group, we compiled a concatenated alignment of nuclear and mitochondrial DNA sequences, comprising representatives of most living and recently extinct species. Our analysis confirmed the currently recognised deep split between Macrotis (Thylacomyidae), Chaeropus (Chaeropodidae) and all other living bandicoots (Peramelidae). The mainly New Guinean rainforest peramelids were returned as the sister clade of Australian dry-country species. The wholly New Guinean Peroryctinae was sister to Echymiperinae. The poorly known and perhaps recently extinct Seram Bandicoot (Rhynchomeles) is sister to Echymipera. Estimates of divergence times from relaxed-clock Bayesian methods suggest that living bandicoots originated in the late Oligocene or early Miocene, much earlier than currently thought based on fossils. Subsequent radiations within Peramelemorphia probably took place on the Australian mainland during the Miocene, with diversification of rainforest taxa on the newly emergent New Guinean landmasses through the middle-late Miocene and complete establishment of modern lineages by the early Pliocene.  相似文献   

14.
Chinchilloidea is an emblematical group of caviomorph rodents characterized by euhypsodont, laminated cheek teeth. Recent molecular analyses proposed that the extant Dinomys (and implicitly its fossil allies) is also part of this group. Their relationships with fossil caviomorphs with less derived dental features are still obscured by the deficiency of the fossil record documenting its early dental evolution. The new genus and species Garridomys curunuquem, from the early Miocene deposits of the Cerro Bandera Formation, northern Patagonia, is here described. It is represented by numerous mandible and maxillary remains with dentition. This species has protohypsodont cheek teeth with three transverse crests in all ontogenetic stages arranged in a transitory S-shaped pattern, resembling putative early dinomyids. Garridomys curunuquem is here interpreted as the sister group of the clade including the living and fossil chinchillids; both chinchillas and viscaccias would have diverged from a Garridomys-like ancestor and acquired hypsodonty independently. Garridomys and other chinchilloids would have diverged from the lineage leading to chinchillids in pre-Oligocene times, suggesting a very early, still poorly documented chinchilloid radiation.  相似文献   

15.
The Ortheziidae (ensign scale insects) is a morphologically well‐defined family. The morphology and occurrence in the fossil record suggests a probable early origin of the family in scale insect evolution. The present phylogenetic analysis – based on 69 morphological characters of female ortheziids, using 39 exemplar Recent species – provides the first analytical assessment of relationships among living genera of the family, as well as the relationships of eight fossil species, based on complete, well‐preserved specimens in amber. Monophyly of the subfamilies Newsteadiinae, Ortheziinae and Ortheziolinae is supported, but Nipponortheziinae is found to be paraphyletic by inclusion of the Ortheziolinae. Thus, the subfamily Ortheziolinae is reduced in rank to tribe Ortheziolini stat.n. , which now includes Matileortheziola Kozár & Foldi, Ortheziolacoccus Kozár, Ortheziolamameti Kozár and Ortheziola?ulc. Consequently, the tribes Matileortheziolini, Ortheziolacoccini and Ortheziolamametini are synonymized ( syn.n. ) here under Ortheziolini. Five new species and one new genus of fossil ensign scales are described from three amber deposits: Burmorthezia gen.n. with type species Burmorthezia kotejai sp.n. and also B. insolita sp.n ., both in mid‐Cretaceous Burmese amber (98 Ma) and Arctorthezia baltica sp.n. in Eocene Baltic amber (c. 43 Ma) based on second‐instar nymphs; Mixorthezia kozari sp.n . and M. dominicana sp.n . in Miocene Dominican amber (c. 17 Ma) based on adult females. Fossil placements are unambiguous, with Burmorthezia forming a stem to crown‐group (Recent and Tertiary) Ortheziidae. A summary of described fossil ortheziids is provided.  相似文献   

16.
The genus Calocedrus Kurz is characterized by flattened branches covered with decussate and dimorphic leaves. In this study, we describe fossil foliage of Calocedrus discovered in the Shangcun Formation (early Oligocene) of the Maoming Basin, South China. The fossils have wedge‐shaped branchlet segments and scale‐like strongly dimorphic leaves, similar to the fossil species Calocedrus lantenoisi (Laurent) Tao. There have been no detailed studies of the morphological features and cuticle structures of C. lantenoisi. Therefore, a newly emended diagnosis of the species C. lantenoisi is given based on a detailed study of leaf morphology and cuticular characters exhibited by the Maoming fossils. This is one of the earliest fossil records of Calocedrus in the world, providing additional evidence for the early biogeographic history of this genus and supporting the inference that eastern Asian Calocedrus is primitive among all the living species. The extant species of Calocedrus are mainly distributed in mountainous regions. On the basis of the “nearest living relative” analysis, we propose that the Maoming Basin was adjacent to a mountainous region during the early Oligocene.  相似文献   

17.
The evolution of increased tooth crown height is considered to be an adaptation for coping with excessive rates of dental wear associated with abrasive herbivorous diets, such as grazing and(or high levels of exogenous grit (e.g. dust, sand, ash). Evolutionary trends in the crown heights of North American ungulates are grossly consistent with a transition from closed forests in the early Eocene to open grasslands in the late Miocene. However, the evolutionary proliferation of hypsodonty (high crowned teeth) in the early and middle Miocene occurs later than the apparent origin of open grassland habitats in North America. The paleoecology of species from the interval between the appearance of grasslands and the evolutionary proliferation of hypsodonty is critical to understanding the role of Cenozoic climate change in mammalian evolution. The paleodiets of late Eocene to middle Miocene oreodonts (Merycoidodontidae) were reconstructed by examining the relative facet development of molars (mesowear). A two-phase diet trend was discovered. Phase 1 suggests either an average reduction in the amount of exogenous grit from the late Eocene to early Oligocene or a decrease in fruit consumption related to the disappearance of more wooded habitats. Phase 2 is a gradual transition from early Oligocene low-abrasion browsing to high abrasion diets similar to mixed feeding and grazing in the Miocene. According to mesowear data, oreodont diets similar to those of modern grazers in terms of abrasion are not seen until the early Miocene (early Hemingfordian land mammal age). The coevolutionary relationship of molar crown height and diet, as represented by mesowear, was examined using phylogenetically independent contrasts. No significant coevolutionary relationship was found. In several instances, diet was found to shift over time despite morphological stasis (i.e. within a single species). These results do not clearly indicate that the overall trend of increasing dietary abrasion imposed sufficient selection to drive crown height evolution in oreodonts. Therefore, direct fossil evidence of dietary abrasion as a causal factor in the evolution of crown height, at least in this clade, is elusive.  相似文献   

18.
This paper reviews the non-dental morphological configuration of Miocene hominoids with special reference to the hypothesis of linear relationships between certain fossil species and living analogues. Metrical analysis of the wrist shows thatDryopithecus africanus andPliopithecus vindobonensis are unequivocally affiliated with the morphological pattern of quadrupedal monkeys. Similar analyses of the fossil hominoid elbow shows that they are more cercopithecoid-like than hominoid-like. Multivariate analysis of theP. vindobonensis shoulder in the matrix of extant Anthropoidea indicate that this putative hylobatine fossil shows no indication of even the initial development of hominoid features. The total morphological pattern of theD. africanus forelimb as assessed by principal coordinates analysis of allometrically adjusted shape variables has little resemblance toPan. Likewise, the feet and proximal femora of the Miocene fossils are unlike any living hominoid species. Even theD. africanus skull is similar to extant cercopithecoids in several features. Although ancestors cannot be expected to resemble descendants in every way, the striking dissimilarity between Miocene and extant hominoids seems to eliminate the consideration of a direct ancestor-descendant relationship between specific Miocene and modern forms.  相似文献   

19.
Aim To resolve the phylogeny of humans and their fossil relatives (collectively, hominids), orangutans (Pongo) and various Miocene great apes and to present a biogeographical model for their differentiation in space and time. Location Africa, northern Mediterranean, Asia. Methods Maximum parsimony analysis was used to assess phylogenetic relationships among living large‐bodied hominoids (= humans, chimpanzees, bonobos, gorillas, orangutans), and various related African, Asian and European ape fossils. Biogeographical characteristics were analysed for vicariant replacement, main massings and nodes. A geomorphological correlation was identified for a clade we refer to as the ‘dental hominoids’, and this correlation was used to reconstruct their historical geography. Results Our analyses support the following hypotheses: (1) the living large‐bodied hominoids represent a monophyletic group comprising two sister clades: humans + orangutans, and chimpanzees (including bonobos) + gorillas (collectively, the African apes); and (2) the human–orangutan clade (dental hominoids) includes fossil hominids (Homo, australopiths, Orrorin) and the Miocene‐age apes Hispanopithecus, Ouranopithecus, Ankarapithecus, Sivapithecus, Lufengpithecus, Khoratpithecus and Gigantopithecus (also Plio‐Pleistocene of eastern Asia). We also demonstrate that the distributions of living and fossil genera are largely vicariant, with nodes of geographical overlap or proximity between Gigantopithecus and Sivapithecus in Central Asia, and between Pongo, Gigantopithecus, Lufengpithecus and Khoratpithecus in East Asia. The main massing is represented by five genera and eight species in East Asia. The dental hominoid track is spatially correlated with the East African Rift System (EARS) and the Tethys Orogenic Collage (TOC). Main conclusions Humans and orangutans share a common ancestor that excludes the extant African apes. Molecular analyses are compromised by phenetic procedures such as alignment and are probably based on primitive retentions. We infer that the human–orangutan common ancestor had established a widespread distribution by at least 13 Ma. Vicariant differentiation resulted in the ancestors of hominids in East Africa and various primarily Miocene apes distributed between Spain and Southeast Asia (and possibly also parts of East Africa). The geographical disjunction between early hominids and Asian Pongo is attributed to local extinctions between Europe and Central Asia. The EARS and TOC correlations suggest that these geomorphological features mediated establishment of the ancestral range.  相似文献   

20.
《Palaeoworld》2021,30(4):746-756
A new fossil species, Cedrus anatolica n. sp., is described from the early Miocene Hançili Formation of Turkey. All analyses were performed on the thin sections housed at Istanbul University – Cerrahpasa. The new species was interpreted as having the closest affinity with the modern Mediterranean species Cedrus atlantica (Endlicher) Manetti ex Carriere and Cedrus libani Richard. The evolutionary line shows some changes in wood anatomy. From the early Cretaceous to the early Miocene, the pits on the tangential walls of the tracheids gradually decreased, the height of rays increased and the number of epithelial cells in the traumatic resin canals increased slightly. These features are similar in three modern species; other wood anatomical features are also quite stable among the new fossil and modern species.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号