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Features of the fossil record of evolution

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Neither allopatric speciations nor extinctions of lineages are directly observable in the fossil record. This significantly reduces the value of inferred durations of taxa as a basis for studies on patterns of evolution. The ranges of taxa detected in rock strata are inevitably shorter than the real durations of lineages. Rates of evolution estimated by counting reported ranges of taxa therefore appear higher than they really were. Biometric studies of gradually evolving lineages indicate that the durations of ‘species’ (morphologies) were actually many times longer. Therefore, the ancestor-descendant relationships along monospecific lineages remain the most important subjects of study in evolutionary paleontology. A way, in which an ancestor-descendant hypothesis can be falsified, is presented.
Plesiosauria is a clade of medium to large bodied marine reptiles with a cosmopolitan distribution ranging from the latest Triassic to the end of the Cretaceous. In Europe, the fossil record of Plesiosauria is mainly known from the Northern latitudes, whereas it is much rarer from the Southern and Mediterranean areas. Here, we report the first articulated skeleton of an Italian plesiosaurian, from the Callovian–Oxfordian deposits of the Rosso Ammonitico Veronese Formation of Kaberlaba (Veneto). The specimen is referred to Pliosauridae based on the large size of the skull, compared to the appendicular skeleton, the presence of the lacrimal, and a distinct anterolateral projection of the prefrontal into the orbital margin. Mandibular and vertebral symplesiomorphies support the placement of the Italian taxon among the “gracile-longirostrine grade” of basal pliosaurids. The Kaberlaba plesiosaurian represents the second reptile clade recovered from the Rosso Ammonitico Veronese Formation, after Thalattosuchia.
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The conulariids, an enigmatic fossil group believed to be of cnidarian (scyphozoan) affinity, have four−sided, acutely pyramidal exoskeletons terminated in apertural closures. To date, three main closure types have been recognised in conulariids (plicated, triangular lappets, and lobate lappets) but the first type is poorly illustrated in the literature. Here we present the first photographic illustration of an unequivocal plicated closure in Metaconularia? anomala, based on study of the rich (1700+ specimens) material from the Upper Ordovician of the Prague Basin. This closure is formed by inwardly folded, triangular lappets centred on each of the four faces, with kite−shaped elements centred on the four corners forming a webbing between the lappets. Plicated closures were evidently rare in conulariids and restricted to a few Ordovician species.
A brief review of the present state of palaeontological knowledge on the superfamily Curculionoidea is presented. The taxonomic position of Triassic weevil-like beetles is disputable. The oldest diverse weevil fauna known from the Upper Jurassic reflects an early stage of radiation of lineages ancestral for modern primitive weevil families. An extensive radiation of more advanced families occurred mainly in the Cretaceous, most of modern subfamilies existed in the Early Tertiary, and the main radiation of living tribes in Curculionidae was probably in the Oligocene and Miocene. The robustness of palaeontological data on the weevil history is discussed. The new combination Pseudaspidapion khnzoriani is proposed for Apion khnzoriani ZHERIKHIN 1971, from the Baltic amber.
Eleven new tracks from the Upper Jurassic of Portugal are described and attributed to the stegosaurian ichnogenus Deltapodus. One track exhibits exceptionally well−preserved impressions of skin on the plantar surface, showing the stegosaur foot to be covered by closely spaced skin tubercles of ca. 6 mm in size. The Deltapodus specimens from the Aalenian of England represent the oldest occurrence of stegosaurs and imply an earlier cladogenesis than is recognized in the body fossil record.
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Termites of the family Stolotermitidae are a relict lineage of primitive Isoptera. The fossil record of Stolotermitidae is exceptionally poor, with only two Miocene (Neogene) species documented to date. Herein, a new genus and species of Paleogene termites is described and figured from the Late Oligocene (28–27 Ma, Early Chattian) of northwestern Ethiopia (Amhara Region, Chilga Woreda). Chilgatermes diamatensis gen. et sp. nov., is most similar to genera of the Stolotermitidae, Archotermopsidae, and Termopsidae but can be distinguished on the basis of forewing venational details. The genus is tentatively placed in the Stolotermitidae: Porotermitinae. Chilgatermes diamatensis is the first fossil termite from Ethiopia and, indeed, the first from the entire African continent.
To evaluate stratigraphic evidence for the time of origin of the clade of extant amphibians (Lissamphibia), we attempt to establish a confidence interval on the lower bound of the stratigraphic range of this clade. This is based on the stratigraphic distribution of 1207 fossiliferous localities that have yielded lissamphibians, the relative area of sedimentary rocks from various periods (upper Paleozoic to present) exposed on the continents, and ten exponential−growth models of lissamphibian diversity that differ by the assumed effects of three major biological crises and the assumed starting times of lissamphibian diversification. The results suggest a more recent origin of Lissamphibia than advocated in most recent molecular studies. They are also more compatible with monophyly than with polyphyly of the extant amphibians, but heavily depend on poorly constrained assumptions about lissamphibian extinction rates during biological crises. Counts of lissamphibian diversity through time that consider ghost lineages and stage durations show moderate declines across the Cretaceous–Paleogene and Oligocene–Miocene boundaries.
Described here is a partial postcranial skeleton and additional disarticulated but associated bones of the new fossil penguin Spheniscus muizonisp. nov. from the latest middle/earliest late Miocene (11–13 Ma) locality of Cerro la Bruja in the Pisco Formation, Peru. This fossil species can be attributed to the extant genus Spheniscus by postcranial morphology and is the oldest known record of this genus. Spheniscus muizonisp. nov. is about the size of the extant Jackass and Magellanic penguins (Spheniscus demersus and Spheniscus magellanicus). Beside Spheniscus urbinai and Spheniscus megaramphus it is the third species of Spheniscus represented in the Pisco Formation. This study contains morphological comparisons with Tertiary penguins of South America and with most of the extant penguin species.
Acta Ornithologica
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2008
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tom 43
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nr 2
226-230
The phylogenetic affinities and evolutionary history of the Madagascan Leptosomidae (Courol or "Cuckoo-roller") are reviewed to rectify erroneous accounts in the recent literature. These birds are not closely related to rollers, and multiple molecular and morphological data sets congruently support their position outside the clade including Coraciiformes sensu stricto (rollers and ground rollers), Piciformes (woodpeckers and allies), and Alcediniformes (kingfishers and allies). The recent discovery that Plesiocathartes, from the Eocene of Europe and North America, is a stem lineage representative of the Leptosomidae further shows that Pan-Leptosomidae were widely distributed across the Northern Hemisphere in the early Paleogene. The Courol is among the few avian taxa which qualify as "living fossils", and its persistence on Madagascar may have been facilitated by the absence of ecological factors that led to extinction of Pan-Leptosomidae elsewhere.
The fossil turtle Kayentachelys aprix is known from Early Jurassic sediments of the Kayenta Formation, Arizona, USA. The detailed description of this taxon’s cranium offered in this paper demonstrates that this turtle presents a mixture of primitive and derived character states. Among others, the presence of an interpterygoid vacuity, a basipterygoid process, a prootic that is exposed in ventral view, and a foramen posterius canalis carotici interni that is formed entirely by the basisphenoid are generally considered primitive for turtles. On the other hand, the presence of an undivided apertura narium, a well developed cavum tympani, an incipient cavum postoticum, and an unpaired vomer are considered to be derived. Kayentachelys aprix has previously been hypothesized to be the oldest stem cryptodiran turtle because of the presence of a flat, vertical plate on the processus pterygoideus externus, and the presence of a processus trochlearis oticum. However, the presence of these characters cannot be confirmed in the available specimens. Other putative stemcryptodiran characters, such as the prefrontal−vomer contact and the presence of an epipterygoid, are herein corroborated as being symplesiomorphies, because they generally appear to be present in basal turtles.
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We describe a new avian taxon (Sanshuiornis zhangi gen. et sp. nov.) from Middle Eocene black oil shales in the Huayong Formation of Guangdong Province, south China. The specimen consists of a distal tibiotarsus and a complete foot with tarsometatarsus and pedal digits in articulation. A preliminary phylogenetic analysis does not resolve the affinities of the fossil, but the bones show resemblances to some “ciconiiform” birds. The peculiar hypotarsus morphology, which is block−like and exhibits four cristae, resembles that of the early Eocene Rhynchaeites, which is a stem group representative of the Threskiornithidae. The new Chinese fossil has, however, proportionally longer legs than Rhynchaeites and its phylogenetic affinities probably cannot be resolved without further material.
Feeding traces for carnivorous theropod dinosaurs are typically rare but can provide important evidence of prey choice and mode of feeding. Here we report a humerus of the hadrosaurine Saurolophus which was heavily damaged from feeding attributed to the giant tyrannosaurine Tarbosaurus. The bone shows multiple bites made in three distinctive styles termed “punctures”, “drag marks” and “bite−and−drag marks”. The distribution of these bites suggest that the animal was actively selecting which biting style to use based on which part of the bone was being engaged. The lack of damage to the rest of the otherwise complete and articulated hadrosaur strongly implies that this was a scavenging event, the first reported for a tyrannosaurid, and not feeding at a kill site.
Some solitary caryophylliid (Caryophyllia, Trochocyathus, and Ceratotrochus) and flabellid (Flabellum) scleractinian corals from Pliocene of Western Mediterranean exhibit long groove−shaped bioersional structures running along the surface of the thecae. They are epigenic structures produced by an episkeletozoan and therefore, they are described as Fixichnia. Here we propose Sulcichnus as a new ichnogenus, with three new ichnospecies (Sulcichnus maeandriformis, S. helicoidalis, and S. sigillum) to name this traces. Sulcichnus is attributed to the activity of polychaetes. Similar structures are recently produced by Lumbrineris flabellicola, a symbiotic eunicid which maintains a commensalistic relationship with solitary corals. In the fossil record, Sulcichnus occurs associated to shallow marine environments whereas their Recent counterparts are described on deep−marine corals. We interpret this as a consequence of a change in the environmental requirements of the coral/worm pair.
Boobies and gannets (family Sulidae) are the most specialized plunge divers among seabirds. Their fossil record along the Pacific coast of South America extends to the early Middle Miocene. Here we describe three new species of sulids: Sula brandi sp. nov., Sula figueroae sp. nov., and Ramphastosula aguirrei sp. nov., from the early Late Miocene of the Pisco Formation (Peru). Two of them are relatives of the living genus Sula, which represents medium and large-sized boobies. A new species of the extinct genus Ramphastosula is also described, adding to the discussion of possible alternative feeding strategies among sulids. The fossil record suggests that sympatric sulids exhibit different body sizes at least since the Oligocene epoch, a strategy related with resource partitioning. Furthermore, we find current analysis and knowledge of the fossil record unsuitable to evaluate properly seabird diversity changes through time.
Of the 30 extant orders of insects, scale insects (Hemiptera: Coccoidea) have one of the best fossil records among insects that probably extends to the early Mesozoic. Most fossil Coccoidea records are of adult males which have been trapped in amber, whereas adult females are less common, probably because of their sedentary occurrence on plants. Descriptions, photos, and SEM micrographs are presented of over 250 well−preserved scale covers of adult females and nymphal stages of armoured scale insects (Hemiptera: Coccoidea: Diaspididae) which were found on dicotyledonous and monocotyledonous fossil leaves in Middle Eocene deposits from Germany. The structure of these fossil scale covers closely agrees with that of extant Diaspididae. These armoured scale insects belong to the subfamily Aspidiotinae. The age of this insect−plant association—47 to 44 million−year−old—indicates that the Diaspididae have a long history in the Palaearctic region.
Considering the fossil record, foraminifers constitute one of the most ubiquitous groups in marine deposits due to a high preservation potential of tests. Moreover, borings appear to be widely distributed in the tests. Findings of the borings have potential usefulness as palaeoecological markers and can be significant for taphonomical studies of foraminifers. Formal naming of the borings is needed to further their usefulness, and therefore a new ichnotaxon Curvichnus semorbis igen. et isp. nov. is erected.
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