禄丰古猿化石地点的植物叶化石

1987年,在云南禄丰古猿化石地点D剖面第4层(薄层黑色炭质粘土与灰色细砂互层)发现植物叶部印痕化石,经鉴定属壳斗科绝灭的雷龙潭槲叶(Dryophyllum relongtanense Colani),该种植物常参与组成亚热带至暖温带的常绿阔叶林或常绿与落叶阔叶混交林。     

Fish remains from the Plio-Pleistocene Shungura Formation, Omo River basin, Ethiopia

Thousands of vertebrate fossils have been recovered from the lower Omo River Valley, in southern Ethiopia, however, fishes have been poorly reported. Here we describe fossil fish remains deriving from the Shungura Formation, part of the Omo Group of deposits ranging in date from 1.8 to 3.4 my. Two new species are reported, Sindacharax omoensis (Characiformes) and Lates arambourgi (Perciformes), which suggest greater diversity of these genera than previously documented.     

Permineralized rhizomes of the Osmundaceae (Filicales): Diversity and tempo-spatial distribution pattern

The family Osmundaceae is among the most primitive ferns of the Filicales, with an extensive fossil record dating back to the Late Paleozoic. Numerous fossil osmundaceous rhizomes have been documented in the geological history. However, the diversity, variation and distribution pattern of permineralized rhizomes remain poorly known. Here we intend to analyze the fossil records with regard to the diversity and distribution pattern of the osmundaceous rhizomes based on available data. To date, about 83 species ascribed to 14 genera of fossil osmundaceous rhizomes have been described worldwide, assigned to two subfamilies, namely, Thamnopteroideae and Osmundoideae. Geologically, two groups (i.e., Thamnopteroideae and Palaeosmunda) have been reported in the Permian. All the Triassic taxa are from the southern hemisphere. Jurassic osmundaceous rhizomes are abundant and widespread throughout the world, most dominant in the southern hemisphere. During the transition of Jurassic to Cretaceous, the diversity of osmundaceous rhizomes declined rapidly. In the Cretaceous, however, the osmundaceous rhizomes from the northern hemisphere surpass those from the southern hemisphere in generic level for the first time. The Cenozoic taxa diversified in the northern hemisphere with the rise of angiosperms. Geographically, the osmundaceous fossil rhizomes have been found in both hemispheres; the major localities include Ural area of the former USSR, Tasmania of Australia, southern Argentina, Antarctica, northern India, central and western part of North America and northern China. We discuss the origin, radiation, and development of the Osmundaceae based on rhizomes, to help further understand the systematic relation and evolutionary history of the family Osmundaceae.     

A SKULL OF THE GIANT BONY‐TOOTHED BIRD DASORNIS (AVES: PELAGORNITHIDAE) FROM THE LOWER EOCENE OF THE ISLE OF SHEPPEY

Abstract: The first substantial skull of a very large Paleogene bony‐toothed bird (Pelagornithidae) is described from the Lower Eocene London Clay of the Isle of Sheppey in England. The specimen is assigned to Dasornis emuinus (Bowerbank), based on a taxonomic revision of the large London Clay Pelagornithidae. Very large bony‐toothed birds from the London Clay were known previously from fragmentary remains of non‐comparable skeletal elements only, and Dasornis londinensis Owen, Argillornis emuinus (Bowerbank), A. longipennis Owen, and Neptuniavis miranda Harrison and Walker are considered junior synonyms of D. emuinus. The new specimen allows a definitive assignment of Dasornis to the Pelagornithidae and documents that this taxon closely resembles other bony‐toothed birds in cranial morphology. It is hypothesized that giant size (i.e. a wingspan above 4 m) evolved only once within Pelagornithidae and that Dasornis emuinus is the sister taxon of the giant Neogene bony‐toothed birds, which share a derived wing morphology.     

Taphonomic windows and molluscan preservation

Recent studies on silicified fossil biotas have suggested that substantial skewing of the molluscan record resulted from early aragonite dissolution in mid-outer carbonate ramp settings. If those rare skeletal lagerstätten are representative, then the quality and completeness of the molluscan record are thrown into doubt. Yet database studies suggest that the bivalve fossil record is actually relatively complete. If so, then biodiversity must be captured by other processes that preserved shells vulnerable to early dissolution, and which operated on a relatively high frequency, i.e., less than the species duration for bivalves.Storm beds, shell plasters and submarine hardgrounds are identified as fossil deposits that can preserve the labile aragonitic component of the fauna and thus represent potential taphonomic windows. Many storm event beds include rich accumulations of shelly benthos. Differences between storm bed faunas and those of the background facies could reflect transportation effects. However, some storm bed assemblages are rich in originally aragonitic infaunal bivalves that are not represented in background facies or more proximal shelf equivalents, and here rapid burial and removal of organic matter by winnowing may be the keys to aragonite shell preservation. Despite Palaeozoic to Cenozoic changes in the thickness and frequency of shell beds that reflect the predominant bioclast producers, shallow infaunas are commonly concentrated together with epifauna in such deposits.Some low energy, organic-rich mud-dominated settings are associated with preservation of aragonitic molluscs. Infaunal bivalves are a prominent component of shell plasters or pavements in such settings, linked to episodic bottom water anoxia. Decaying algal blooms drew the redox boundary up above the sediment–water interface, and brought populations of infaunal bivalves to the surface where they died. Isolated from the oxic taphonomically active zone, the shells were not dissolved and were buried as thin shell layers. In similar settings, aragonitic shells were preserved as moulds through early pyritisation, or even through preservation of original shell aragonite.In oxic environments, bioturbational reworking of surface sediment destroyed moulds of aragonitic shells after early dissolution. In some hardgrounds, these delicate moulds were preserved due to synsedimentary cementation, probably using carbonate released by aragonite dissolution. The examples included here come from both intervals of “calcite” and “aragonite” seas, and it is not possible to assess whether the saturation state (with respect to aragonite) of the ambient sea water played a role in the selective removal of aragonitic shells.While taphonomic windows may have captured the diversity of individual groups, it is clear from quantitative data involving skeletal lagerstätten that the scale of loss from early aragonite dissolution has drastically altered the trophic composition of some fossil assemblages commonly used as the basis for reconstructions of past communities.     

Fossil insects and ecosystem dynamics in wetlands: implications for biodiversity and conservation

We review the uses of fossil insects, particularly Coleoptera (beetles) and Chironomidae (non-biting midges) from ancient deposits to inform the study of wetland ecosystems and their ecological and restoration processes. In particular, we focus on two contrasting ecosystems, drawing upon research undertaken by us on British raised mire peats and shallow lake systems, one an essentially terrestrial ecosystem, the other aquatic, but in which wetland insects play an important and integral part. The study of raised mire peats suggests that faunal stability is a characteristic of these wetland systems, over what appear to be extensive periods of time (up to several millennia), whilst studies of shallow lake ecosystems over recent timescales indicates that faunal instability appears to be more common, usually driven by increasing eutrophication. Drawing upon a series of fossil Coleoptera records spanning several thousand years from Hatfield Moors, south Yorkshire, we reconstruct in some detail the mire’s ontogeny and fluctuations in site hydrology and vegetation cover, illustrating the intimate association between substrate, topography and peat development. A comparison between fossil and modern beetle populations indicates that the faunal characteristics of this mire and its adjacent neighbour, Thorne Moors, become established during the early phases of peat development, including its rare endemics, and that the faunal biodiversity on the sites today is dictated by complex site histories. The over-riding characteristic of these faunas is of stability over several thousand years, which has important implications for the restoration of degraded sites, especially those where refugial areas are limited. In contrast, analyses of fossil Chironomidae from shallow lakes allow researchers to track changes in limnological status and while attempts have been made to reconstruct changes in nutrient levels quantitatively, the chironomids respond indirectly to such changes, typically mediated through complex ecosystem dynamics such as changes in fish and/or macrophyte communities. These changes are illustrated via historic chironomid stratigraphies and diversity indices from a range of shallow lakes located across Britain: Slapton Ley, Frensham Great Pond, Fleet Pond, Kyre Pool and Barnes Loch. These sites have shown varying degrees of eutrophication over recent timescales which tends to be associated with a decline in chironomid diversity. While complex functional processes exist within these ecosystems, our evidence suggests that one of the key drivers in the loss of shallow lake chironomid diversity appears to be the loss of aquatic macrophytes. Overall, while chironomids do show a clear response to altered nutrient regimes, multi-proxy reconstructions are recommended for a clear interpretation of past change. We conclude that if we are to have a better understanding of biota at the ecosystem level we need to know more of the complex interactions between different insect groups as well as with other animal and plant communities. A palaeoecological approach is thus crucial in order to assess the role of insect groups in ecosystem processes, both in the recent past and over long time scales, and is essential for wetland managers and conservation organisations involved in long term management and restoration of wetland systems     

准噶尔盆地白垩纪轮藻化石组合序列

新疆准噶尔盆地的白垩系发育较好,其中含有丰富的轮藻化石,计有20属1亚属63种1亚种3变种2比较种1新型2未定种,其中包括7个新种。根据轮藻植物群的演化,可在盆地的南缘、腹部和东北缘建立4个化石带1个亚带和1个组合:Clypeator zongjiangensis带(南缘、腹部及东北缘),时代相当于Berriasian-Valanginian;Flabellochara hebeiensis带(南缘),时代为Barremian;Clypeator jiuquanensis带(腹部),时代为Hauterivian-Bar-remian,其中包含Atopochara trivolvis triquetra亚带,时代为Barremian;Atopochara restricta带(腹部),时代为Cenomanian;Aclistochara mundulavar.elliptica-Raskyaechara gobica-Tolypella grambasti组合(腹部、北部及东北缘),时代应为晚白垩世中、晚期。该组合序列的建立,对确定准噶尔盆地白垩系的年代格架以及与国内外有关地层的对比关系具有十分重要的意义。     

A small, “wader-like” bird from the Early Eocene of Messel (Germany)

A small bird with a shorebird-like beak and a very long hind toe is described from the Early Eocene of Messel in Germany. Vanolimicola longihallucis, gen. et sp. nov. is one of the few candidate species for a “wading bird” from Messel, that is, a bird that may have foraged along the shoreline of the ancient lake. A few features indicate a relationship to charadriiform birds and Jacanidae (jacanas) in particular, but charadriiform affinities are only weakly supported. In the preserved skeletal elements, V. longihallucis also resembles the taxon Songzia from the Early Eocene of China, which is considered to be a representative of the Ralloidea (rails and allies). A potential biogeographic significance of the new Messel fossil is strengthened by similar fossils from the North American Green River Formation.     

Functional morphology of cercopithecoid primate metacarpals

The primate fossil record suggests that terrestriality was more common in the past than it is today, particularly among cercopithecoid primates. Whether or not a fossil primate habitually preferred terrestrial substrates has typically been inferred from its forelimb anatomy. Because extant large-bodied terrestrial cercopithecine monkeys utilize digitigrade hand postures during locomotion, being able to identify if a fossil primate habitually adopted digitigrade postures would be particularly revealing of terrestriality in this group. This paper examines the functional morphology of metacarpals in order to identify osteological correlates of digitigrade versus palmigrade hand postures. Linear measurements were obtained from 324 individuals belonging to digitigrade and palmigrade cercopithecoid species and comparisons were made between hand posture groups. Digitigrade taxa have shorter metacarpals, relative to both body mass and humerus length, than palmigrade taxa. Also, digitigrade taxa tend to have metacarpals with smaller dorsoventral diameters, relative to the product of body mass and metacarpal length, compared to palmigrade taxa. The size and shape of the metacarpal heads do not significantly differ between hand posture groups. Multivariate analyses suggest that metacarpal shape can only weakly discriminate between hand posture groups. In general, while there are some morphological differences in the metacarpals between hand posture groups, similarities also exist that are likely related to the fact that even digitigrade cercopithecoids can adopt palmigrade hand postures in different situations (e.g., terrestrial running, arboreal locomotion), and/or that the functional demands of different hand postures are not reflected in all aspects of metacarpal morphology. Therefore, the lack of identifiable adaptations for specific hand postures in extant cercopithecoids makes it difficult to determine a preference for specific habitats from fossil primate hand bones.     

A comparative analysis of vibrissa count and infraorbital foramen area in primates and other mammals

Vibrissae are specialized sensory “hairs” that respond to mechanical stimuli. Sensory information from vibrissae is transmitted to the brain via the infraorbital nerve, which passes through the infraorbital foramen (IOF). Several analyses have documented that primates have smaller IOFs than non-primate mammals, and that haplorhines have smaller IOFs than strepsirrhines. These grade shifts in IOF area were attributed to differences in “vibrissa development.” Following earlier analyses, IOF area has been used to derive a general estimate of “whiskeredness” in extinct primates, and consequently, IOF area has been used in phylogenetic and paleoecological interpretations. Yet, the relationship between IOF area and vibrissa count has not been tested, and little is known about how IOF area and vibrissa counts vary among mammals. This study explores how relative IOF area and vibrissa count differ among 25 mammalian orders, and tests for a correlation between IOF area and vibrissa count. Results indicate that primates and dermopterans (Primatomorpha) have smaller IOFs than most non-primate mammals, but they do not have fewer vibrissae. In addition, strepsirrhines and haplorhines do not differ from one another in relative IOF area or vibrissa counts. Despite different patterns documented for IOF area and vibrissa count variation across mammals, results from this study do confirm that vibrissa count and IOF area are significantly and positively correlated (p < 0.0001). However, there is considerable scatter in the data, suggesting that vibrissa counts cannot be predicted from IOF area. There are three implications of these finding. First, IOF area reflects all mechanoreceptors in the maxillary region, not just vibrissae. Second, IOF area may be an informative feature in interpretations of the fossil record. Third, paleoecological interpretations based on vibrissae are not recommended.