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1.
Tyler, J. C. & Santini, F. (2005). A phylogeny of the fossil and extant zeiform-like fishes, Upper Cretaceous to Recent, with comments on the putative zeomorph clade (Acanthomorpha). — Zoological Scripta , ** , ***–***.
A phylogenetic hypothesis based on 107 morphological characters is proposed for a data set of 43 taxa. Thirty-three are extant and belong to the orders Zeiformes (20 taxa), Caproiformes (2), Tetraodontiformes (2), Beryciformes (3), Stephanoberyciformes (3) and Perciformes (3). Ten are fossil taxa previously assigned to the Zeiformes (3), Caproiformes (1), Tetraodontiformes (2), Perciformes (1), and to two extinct Eocene families, the Sorbinipercidae (2) and the Zorzinichthyidae (1). This analysis indicates the existence of a previously undocumented clade formed by the families Sorbinipercidae + Zorzinichthyidae that may be related to the tetraodontiforms. It also shows that two uppermost Palaeocene species, Archaeozeus skamolensis and Protozeus kuehnei , sequentially represent the two most basal lineages of zeiforms, whereas the most ancient known zeiform, the Upper Cretaceous Cretazeus rinaldii , belongs within the clade of extant species in a polytomy with many other zeiform lineages. A reduced data set of 25 mostly zeiform taxa, after the removal of most outgroups, shows at least weak support for Cretazeus being nested deeply within the extant zeiforms; such a placement would indicate that at least six lineages of zeiforms were present during the Upper Cretaceous, and survived the Cretaceous/Tertiary (K/T) extinction to radiate in Cenozoic seas.  相似文献   

2.
We describe a new ammonoid fauna from the Taurus Mountains of southern Turkey. The Carnian ammonoid fauna from A?a?iyaylabel is presented for the first time. Ammonoids were obtained from limestone to marl beds of an approximately 35‐m‐thick section, which presents the rare opportunity to investigate ammonoid faunas across the Lower–Upper Carnian boundary. Intense sampling near the village of A?a?iyaylabel led to the recognition of a new Lower Carnian (Julian 2) to Upper Carnian (Tuvalian 1) ammonoid fauna from the Kasimlar Formation. The genus Kasimlarceltites gen. nov. is reported for the first time from the Taurus Mountains, which represents the main faunal element and occurs as huge mass occurrence (n ? 1 million). Kasimlarceltites krystyni gen. et sp. nov., Klipsteinia disciformis sp. nov. and Anasirenites crassicrenulatus sp. nov. occur within the Lower Carnian Carbonate member (Units A–B) of the Kasimlar Formation from the Taurus Platform Units. Ammonoids described from the marls of the Tuvalian Marlstone member were deposited during a major, Tethyan‐wide climate crisis – the so‐called Carnian crisis – characterized by a demise of carbonate platforms. Based on the biostratigraphic relevance of certain ammonoid taxa described herein, the age of the analysed parts of the Kasimlar Formation is Julian 2 to Tuvalian 1. The discovery of the new ammonoid assemblages from A?a?iyaylabel substantiates the significance of Upper Triassic faunas within the Taurus Mountains and facilitates the correlation with faunal assemblages from other regions in the Tethyan Realm. The ammonoid fauna and facies indicate a general deepening from open‐platform margins, over deeper shelf settings down to an open marine‐influenced basinal environment. The tentative habitat for Kasimlarceltites gen. nov. is a shallow platform environment to upper mid‐ramp.  相似文献   

3.
Amphipods from the genus Niphargus represent an important part of the Western Palearctic subterranean fauna. The genus is morphologically diverse, comprising several distinct ecomorphs bound to microhabitats in the subterranean environment. The most impressive among them are “lake giants,” a series of massive, large‐bodied species. These range from morphologically distinct to morphologically cryptic taxa. We analysed the taxonomic structure of the Niphargus arbiterNiphargus salonitanus species complex, belonging to “lake giants” from the Dinaric Karst (West Balkans), and assessed their phylogenetic, morphological and ecological diversity. Multilocus phylogeny suggested that the complex is monophyletic and nested within other cave lake ecomorphs. Unilocus and multilocus coalescence species delimitations indicated that the complex totals nine species. These species substantially overlap in morphology and cannot be unambiguously told apart without the use of molecular markers. An analysis of splitting events within a palaeogeological context, and modelling of environmental characteristics on the phylogeny unveiled a complex history of diversification. Part of this diversification might have been influenced by ecological divergence along the altitudinal gradient reaching from the Adriatic coast to inland Dinaric mountain chains and Poljes. Other splits coincide with the marine regression–transgression cycles during Pliocene. We describe Niphargus alpheus sp. n., Niphargus anchialinus sp. n., Niphargus antipodes sp. n., Niphargus arethusa sp. n., Niphargus doli sp. n., Niphargus fjakae sp. n. and Niphargus pincinovae sp. n., and by doing so hope to prompt their further research.  相似文献   

4.
Ecological opportunity is a powerful driver of evolutionary diversification, and predicts rapid lineage and phenotypic diversification following colonization of competitor‐free habitats. Alternatively, topographic or environmental heterogeneity could be key to generating and sustaining diversity. We explore these hypotheses in a widespread lineage of Australian lizards: the Gehyra variegata group. This clade occurs across two biomes: the Australian monsoonal tropics (AMT), where it overlaps a separate, larger bodied clade of Gehyra and is largely restricted to rocks; and in the larger Australian arid zone (AAZ) where it has no congeners and occupies trees and rocks. New phylogenomic data and coalescent analyses of AAZ taxa resolve lineages and their relationships and reveal high diversity in the western AAZ (Pilbara region). The AMT and AAZ radiations represent separate radiations with no difference in speciation rates. Most taxa occur on rocks, with small geographic ranges relative to widespread generalist taxa across the vast central AAZ. Rock‐dwelling and generalist taxa differ morphologically, but only the lineage‐poor central AAZ taxa have accelerated evolution. This accords with increasing evidence that lineage and morphological diversity are poorly correlated, and suggests environmental heterogeneity and refugial dynamics have been more important than ecological release in elevating lineage diversity.  相似文献   

5.
Abstract: Abundant material from a new quarry excavated in the lower Cambrian Emu Bay Shale (Kangaroo Island, South Australia) and, particularly, the preservation of soft‐bodied features previously unknown from this Burgess Shale‐type locality, permit the revision of two bivalved arthropod taxa described in the late 1970s, Isoxys communis and Tuzoia australis. The collections have also produced fossils belonging to two new species: Isoxys glaessneri and Tuzoia sp. Among the soft parts preserved in these taxa are stalked eyes, digestive structures and cephalic and trunk appendages, rivalling in quality and quantity those described from better‐known Lagerstätten, notably the lower Cambrian Chengjiang fauna of China and the middle Cambrian Burgess Shale of Canada.  相似文献   

6.
Ornithischia is a morphologically and taxonomically diverse clade of dinosaurs that originated during the Late Triassic and were the dominant large‐bodied herbivores in many Cretaceous ecosystems. The early evolution of ornithischian dinosaurs is poorly understood, as a result in part of a paucity of fossil specimens, particularly during the Triassic. The most complete Triassic ornithischian dinosaur yet discovered is Eocursor parvus from the lower Elliot Formation (Late Triassic: Norian–Rhaetian) of Free State, South Africa, represented by a partial skull and relatively complete postcranial skeleton. Here, the anatomy of Eocursor is described in detail for the first time, and detailed comparisons are provided to other basal ornithischian taxa. Eocursor is a small‐bodied taxon (approximately 1 m in length) that possesses a plesiomorphic dentition consisting of unworn leaf‐shaped crowns, a proportionally large manus with similarities to heterodontosaurids, a pelvis that contains an intriguing mix of plesiomorphic and derived character states, and elongate distal hindlimbs suggesting well‐developed cursorial ability. The ontogenetic status of the holotype material is uncertain. Eocursor may represent the sister taxon to Genasauria, the clade that includes most of ornithischian diversity, although this phylogenetic position is partially dependent upon the uncertain phylogenetic position of the enigmatic and controversial clade Heterodontosauridae. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 648–684.  相似文献   

7.
Two primary competing hypotheses regarding the identity of the sister group of the order Tetraodontiformes exist. The first hypothesis holds that some or all acanthuroid fishes represent the sister of Tetraodontiformes. The second, proposed in 1984 by Rosen, holds that the order Zeiformes is sister to Tetraodontiformes and that the family Caproidae is sister to this Zeiformes + Tetraodontiformes clade. These two hypotheses were tested using data from the single-copy nuclear gene RAG1. Representatives of most major orders of acanthomorph fishes were included to provide an appropriate context in which to place Tetraodontiformes and its hypothesized sister groups. The results of an unweighted parsimony analysis indicate that Zeiformes is not the sister group of Tetraodontiformes. In addition, Caproidae appears unrelated to Zeiformes. A monophyletic Tetraodontiformes was recovered as the sister group of the clade Ephippidae + Drepanidae and was more distantly related to the included zeiform and caproid representatives.  相似文献   

8.
Mountainous areas are characterized by substantial biodiversity and endemicity due to their complex geological history and habitat fragmentation. Hence, it can be assumed that particularly high species richness can be found in organisms with limited dispersal capabilities that inhabit mountain streams. A number of scientific papers focus on molecular phylogeography or traditional taxonomy of species or species groups inhabiting such habitats. However, there is a lack of studies that integrate morphological and molecular data to identify and delineate cryptic species. For practical reasons, uncovering cryptic diversity is crucial in taxa used in biomonitoring. Distinct species, hard to separate based on morphology only, may have different tolerance ranges towards a variety of factors. Thus, our goal is to combine the two approaches to reveal potential patterns of diversification within a species widely distributed across European mountains: the amphipod crustacean Gammarus balcanicus. The data were obtained from 13 populations spread across the range of the species. Individuals were initially ascribed to G. balcanicus based on conventional fauna key morpho‐anatomical diagnostic features and were further analysed for 23 additional features to explore any putative diversification. Morphometric data were analysed with use of the multiple correspondence analysis and anova . Molecular distances were calculated for 551‐bp‐long COI sequences. Test for isolation by distance was performed for both morphological and molecular data. The morphometric studies showed that some of the analysed features differed significantly between populations, although there was only a weak correlation between the morphological divergence and the between‐population geographical distances. Moreover, high morphological diversity was present within sites. A set of 42 COI haplotypes was identified among the 135 individuals sequenced. No haplotype was shared among populations. The molecular p‐distances within the nine localities presenting more than one haplotype were either almost null (ca. <0.003 for 7 localities) or relatively low (ca. 0.01–0.02 for 2 localities). In opposite, the molecular p‐distances between localities were mostly at a high level (94% of pairwise comparisons being >0.14), similar as between other well‐defined species of the genus Gammarus. Surprisingly, G. balcanicus appears to be polyphyletic based on topology of the neighbour‐joining tree. The level of genetic distance between localities was not correlated with their geographical proximity. Globally, combining spatial patterns of morphological versus molecular divergence indicates a high level of cryptic diversity within a species conventionally defined based upon fauna key morphological features. In this context, the name G. balcanicus should be applied only to the population from locus typicus, while the other populations represent a number of putative distinct species. We may expect that such phenomenon would apply also to other animal taxa with conserved morphology, which are widespread over different mountain ranges in Europe.  相似文献   

9.
JULIEN DENAYER 《Palaeontology》2011,54(6):1435-1454
Abstract: A rich and diverse coral fauna collected from the Livian (Viséan, Mississippian) of Zonguldak and Bart?n (North‐western Turkey) contains numerous specimens of Dorlodotia and related forms. The most common species, D. delepinei Charles, 1933 , is redetermined as Dorlodotia briarti, an European species. A new species of Dorlodotia is described for very large, phaceloid forms: D. euxinensis. The genus Ceriodotia is created for species close to Dorlodotia with a cerioid habit. It comprises two species: C. bartinensis and C. petalaxoides, both common in the Viséan of Zonguldak and Bart?n. Based on comparison of morphological characters and features of the astogeny, a phylogenetic lineage is proposed for Dorlodotia and the new taxa. The evolution of D. euxinensis from D. briarti is peramorphic. Subsequent paedomorphosis resulted in the lineage D. euxinensisC. bartinensisC. petalaxoides. Ceriodotia probably includes Viséan taxa from Asia previously described as ‘Acrocyathus’.  相似文献   

10.
The taxonomic history of the diatom genus Amphora is one of a broad early morphological concept resulting in the inclusion of a diversity of taxa, followed by an extended period of revision and refinement. The introduction of molecular systematics has increased the pace of revision and has largely resolved the relationships between the major lineages, indicating homoplasy in the evolution of amphoroid symmetry. Within the two largest monophyletic lineages, the genus Halamphora and the now taxonomically refined genus Amphora, the intrageneric morphological and ecological relationships have yet to be explored within a phylogenetic framework. Critical among this is whether the range of morphological features exhibited within these diverse genera are reflective of evolutionary groupings or, as with many previously studied amphoroid features, are nonhomologous when examined phylogenetically. Presented here is a four‐marker molecular phylogeny that includes 31 taxa from the genus Amphora and 77 taxa from the genus Halamphora collected from fresh, brackish, and salt waters from coastal and inland habitats of the United States and Japan. These phylogenies illustrate complex patterns in the evolution of frustule morphology and ecology within the genera and the implications of this on the taxonomy, classification, and organization of the genera are discussed.  相似文献   

11.
Tyrant flycatchers constitute a substantial component of the land bird fauna in all South American habitats. Past interpretations of the morphological and ecological evolution in the group have been hampered by the lack of a well‐resolved hypothesis of their phylogenetic interrelationships. Here, we present a well‐resolved phylogeny based on DNA sequences from three nuclear introns for 128 taxa. Our results confirm much of the overall picture of Tyrannidae relationships, and also identify several novel relationships. The genera Onychorhynchus, Myiobius and Terenotriccus are placed outside Tyrannidae and may be more closely related to Tityridae. Tyrannidae consists of two main lineages. An expanded pipromorphine clade includes flatbills, tody‐tyrants and antpipits, and also Phylloscartes and Pogonotriccus. The spadebills, Neopipo and Tachuris are their closest relatives. The remainder of the tyrant flycatchers forms a well‐supported clade, subdivided in two large subclades, which differ consistently in foraging behaviour, the perch‐gleaning elaeniines and the sallying myiarchines, tyrannines and fluvicolines. A third clade is formed by the genera Myiotriccus, Pyrrhomyias, Hirundinea and three species currently placed in Myiophobus. Ancestral habitat reconstruction and divergence date estimation suggest that early divergence events in Tyrannida took place in a humid forest environment during the Oligocene. Large‐scale diversification in open habitats is confined to the clade consisting of the elaeniines, myiarchines, tyrannines and fluvicolines. This radiation correlates in time to the expansion of semi‐open and open habitats from the mid‐Miocene (c. 15 Mya) onwards. The pipromorphine, elaeniine and myiarchine–tyrannine–fluvicoline clades each employ distinct foraging strategies (upward striking, perch‐gleaning and sallying, respectively), but the degree of diversity in morphology and microhabitat exploitation is markedly different between these clades. While the pipromorphines and elaeniines each are remarkably homogenous in morphology and exploit a restricted range of microhabitats, the myiarchine–tyrannine–fluvicoline clade is more diverse in these respects. This greater ecological diversity, especially as manifested in their success in colonizing a wider spectrum of open habitats, appears to be connected to a greater adaptive flexibility of the search‐and‐sally foraging behaviour.  相似文献   

12.
Despite recent molecular systematic studies on the fossorial southern African skink subfamily Acontinae, evolutionary relationships among the three genera remain unresolved and disputed. Among these, the most recent study suggests that both Typhlosaurus and Acontias are paraphyletic, contrasting earlier results that suggest the presence of two divergent clades within Acontias. Here we further investigate the evolutionary relationships in the limbless fossorial southern African subfamily Acontinae with partial sequenced data derived from four mitochondrial loci (16S rRNA, 12S rRNA, cytochrome oxidase I and cytochrome b), as well as two nuclear protein coding loci (c‐mos and RAG‐1), in an attempt to clarify evolutionary relationships. Phylogenetic results derived from combined data analyses (comprising all six loci and totalling ~3.1 kb) using maximum parsimony, maximum likelihood and Bayesian inferences converged on the same topology. The resulting phylogeny showed Typhlosaurus as monophyletic, while the monotypic genus Acontophiops was nested intermediate to two reciprocally monophyletic Acontias clades. These two Acontias clades can be distinguished on the basis of a number of morphological, morphometric and biogeographical characters, underscoring the presence of two distinct groups. In the present study, we propose the following taxonomic changes based on the multilocus phylogeny. We retain the genus name Acontias for the medium‐ and large‐bodied skinks in clade 2 comprising all taxa in the Acontias meleagris complex as well as Acontias plumbeus, Acontias gracilicauda gracilicauda, Acontias breviceps, Acontias percivali percivali and Acontias percivali occidentalis. We designate a new genus Microacontias gen. nov. for the reciprocally monophyletic taxa in clade 1 comprised of all the small‐bodied taxa that include Microacontias litoralis, Microacontias lineatus lineatus, Microacontias lineatus grayi and Microacontias lineatus tristis. We examine the evolution of characters used in the taxonomy of the Acontinae and suggest that symplesiomorphic morphological characters among fossorial taxa have been an impediment to understanding the evolution of this subfamily. This study underscores the importance of the application of multiple molecular markers (both nuclear and mitochondrial) in determining the taxonomic diversity among fossorial skinks and emphasizes the application of phylogenetics in defining synapomorphic (shared derived) features.  相似文献   

13.
Molecular tools are commonly directed at refining taxonomies and the species that constitute their fundamental units. This has been especially insightful for groups for which species hypotheses are ambiguous and have largely been based on morphological differences between certain life stages or sexes, and has added importance when taxa are a focus of conservation efforts. Here, we examine the taxonomic status of Arsapnia arapahoe, a winter stonefly in the family Capniidae that is a species of conservation concern because of its limited abundance and restricted range in northern Colorado, USA. Phylogenetic analyses of sequences of mitochondrial and nuclear genes of this and other capniid stoneflies from this region and elsewhere in western North America indicated extensive haplotype sharing, limited genetic differences, and a lack of reciprocal monophyly between A. arapahoe and the sympatric A. decepta, despite distinctive and consistent morphological differences in the sexual apparatus of males of both species. Analyses of autosomal and sex‐linked single nucleotide polymorphisms detected using genotyping by sequencing indicated that all individuals of A. arapahoe consisted of F1 hybrids between female A. decepta and males of another sympatric stonefly, Capnia gracilaria. Rather than constitute a self‐sustaining evolutionary lineage, A. arapahoe appears to represent the product of nonintrogressive hybridization in the limited area of syntopy between two widely distributed taxa. This offers a cautionary tale for taxonomists and conservation biologists working on the less‐studied components of the global fauna.  相似文献   

14.
The morphology of two new bivalved arthropods, Loricicaris spinocaudatus gen. et sp. nov. and Nereocaris briggsi sp. nov. from the middle Cambrian (Series 3, Stage 5) Burgess Shale Formation (Collins Quarry locality on Mount Stephen, Yoho National Park, British Columbia, Canada), is described. The material was originally assigned to the genus Branchiocaris, but exhibits distinctive character combinations meriting its assignment to other taxa. Loricicaris spinocaudatus possesses an elongate and spinose abdomen comparable to the contemporaneous Perspicaris and Canadaspis, as well as chelate second head appendages and subtriangular exopods, comparable to Branchiocaris. Nereocaris briggsi possesses a laterally compressed carapace, elongate and delicate appendages and a medial eye located between a pair of lateral eyes on a rhomboidal eye stalk. Although undoubtedly congeneric with Nereocaris exilis from a slightly younger horizon of the Burgess Shale Formation, N. briggsi differs in overall proportions and segment number, warranting assignment to a new species. The newly described taxa were coded into an extensive cladistic analysis of 755 characters, and 312 extinct and extant panarthropods, including a variety of Cambrian bivalved arthropods from both the Burgess Shale and the Chengjiang Lagerstätten. Cambrian bivalved arthropods consistently resolved as a paraphyletic assemblage at the base of Arthropoda. Important innovations in arthropod history such as the specialization of the deutocerebral head appendages and a shift from a nekton‐benthic deposit feeding habit to a benthic scavenging/predatory habit, the symplesiomorphic feeding condition of Euarthropoda (crown‐group arthropods), were found to have occurred among basal bivalved arthropods.  相似文献   

15.
Species in cryptic complexes are, per definition, difficult to identify using morphological characters. One such complex was recently detected in the dung beetle Aphodius fimetarius (Linnaeus) sensu lato, an abundant dung beetle with a wide distribution. While the two component taxa, Aphodius fimetarius sensu stricto and Aphodius pedellus (De Geer) exhibit distinctly different karyotypes, the validity of subtle morphological characters proposed to distinguish between them has been debated. Given the variability and minor interspecific differences in external characters, the large‐scale distribution of respective taxa has remained unknown, as have potential differences in ecology and habits. In this study, we ask how A. fimetarius and A. pedellus can best be distinguished, whether the use of different types of characters (karyotypes, DNA sequences and morphological traits) results in consistent species identification, where these species occur and whether they exhibit ecological differences. In total, we inspected a material of 4401 individuals from across the globe, of which 183 were examined for both mtDNA sequences and morphology, 154 for both morphology and karyotype, and 9 (including the recently proposed neotype of Aphodius fimetarius) for all three types of characters. As a marker gene, we sequenced a 590 bp region of the cytochrome c oxidase I gene for 183 individuals. Overall, DNA sequences offered a clear‐cut distinction between taxa: sequences of A. fimetarius and A. pedellus differed by an average pairwise distance of 8.2%, whereas variation within species was only 0.9% for A. fimetarius and 0.5% for A. pedellus. Morphological and chromosomal characters offered species identifications consistent with that of molecular characters: karyotypes identified as A. pedellus consistently fell within one of the molecular clades, whereas karyotypes identified as A. fimetarius fell within the other clade. Likewise, the majority of individuals identified by morphological characters were assigned to the same species by sequence‐based characters. Both taxa thus defined were found to be Holarctic in distribution, with major sympatry within Central and Southern Europe and mixed patterns of sympatry within the US. Northern areas of Europe, Asia and North America are dominated by A. pedellus alone. Within A. pedellus, patterns of sequence diversity were indicative of a recent population expansion. In the western US, the phenology of a population of A. fimetarius was observed to significantly differ from that of a sympatric population of A. pedellus, thereby revealing an ecological difference between the two cryptic taxa. Overall, we conclude that all types of characters offered a consistent classification of the two species. Thus, the laborious karyotyping techniques used to originally establish the presence of two cryptic taxa can now be substituted by characters more easily applied to large ecological samples. Using this approach of integrative taxonomy, we were able to establish the global distribution and species‐specific ecology of these ecologically important cryptic taxa. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:4033473E-8BF7-40F4-852D-916E4F858593 .  相似文献   

16.
The number of Miniopterus bat species on Madagascar and the nearby Comoros islands (Malagasy region) has risen from four to 11. These recently described cryptic taxa have been differentiated primarily based on molecular markers and associated a posteriori morphological characters that corroborate the different clades. Members of this Old World genus are notably conservative in morphology across their range. Several sites on Madagascar hold up to four small‐bodied taxa of this genus that are morphologically similar to one another, although they can be distinguished based on the tragus, an ear structure associated with echolocation. Miniopterus often emit species‐specific calls. In the present study, we analyze the bioacoustics of the 11 species of Miniopterus currently recognized from the Malagasy region, with an initial identification of the 87 recorded and collected individuals based on molecular markers and certain morphological characters. In most cases, bioacoustic parameters differentiate species and have taxonomic utility. Miniopterus griveaudi populations, which occur on three islands (Madagascar, Anjouan, and Grande Comore), showed no significant differences in peak echolocation frequencies. After running a discriminant function analysis based on five bioacoustic parameters, some mismatched assignments of Malagasy species were found, which include allopatric sister‐taxa and sympatric, phylogenetically not closely‐related species of similar body size. Because the peak echolocation frequencies of two species (Miniopterus sororculus and Miniopterus aelleni) were independent of body size, they were acoustically distinguishable from cryptic sympatric congeners. The small variation around the allometric relationship between body size and peak echolocation frequency of Malagasy Miniopterus species suggests that intraspecific communication rather than competition or prey detection may be the driver for the acoustic divergence of these two species. Our well‐defined echolocation data allow detailed ecological work to commence aiming to test predictions about the relative roles of competition, prey availability, and social communication on the evolution of echolocation in Malagasy Miniopterus species. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 284–302.  相似文献   

17.
Middle and upper Katian conodonts were previously known in the British Isles from relatively small collections obtained from a few localities. The present study is mainly based on 17 samples containing more than 17 000 conodont elements from an approximately 14‐m‐thick succession of the Sholeshook Limestone Formation in a road cut near Whitland, South Wales, that yielded a diverse fauna of more than 40 taxa. It is dominated by representatives of Amorphognathus, Aphelognathus/Plectodina and Eocarniodus along with several coniform taxa. Representatives of Decoriconus, Istorinus and Sagittodontina are reported from the Ordovician of UK for the first time. The fauna is a typical representative of the British Province of the Atlantic Realm and includes a mixture of taxa of North American, Baltoscandic and Mediterranean affinities along with pandemic species. Based on the presence of many elements of Amorphognathus ordovicicus and some morphologically advanced specimens of Amorphognathus superbus, the Sholeshook Limestone Formation is referred to the lower A. ordovicicus Zone. Most of the unit is also coeval with Zone 2 of the Cautleyan Stage in the British regional stage classification, and stage slice Ka3 of the middle Katian Stage in the global stratigraphical classification, an age assignment consistent with data from trilobites, graptolites and chitinozoans. The unusually large collection of M elements of Amorphognathus provides insight into the complex morphological variation in this element of some Katian species of this genus. The Sholeshook conodont fauna is similar to those of the Crûg and Birdshill limestones, but differs in several respects from the slightly older ones from the Caradocian type area in the Welsh Borderland. Although having some species in common, the Sholeshook conodont fauna clearly differs from coeval Baltoscandic faunas and is even more different in composition compared with equivalent North American Midcontinent faunas.  相似文献   

18.
The Viséan succession of the Jerada Massif contains a relatively diverse rugose coral fauna, which comprises 12 genera. Only two of these (Siphonodendron and Lithostrotion) are reported to include more than one species. Most taxa show distinctive facies dependencies. Small solitary corals are found in shaly environments of the Oued Es-Sassi Formation. On the northern flank a coral patch reef formed on an oolitic shoal in the Koudiat Es-Senn Formation. Its core mainly consists of Lithostrotion vorticale colonies, whereas in its surroundings literally hundreds of specimens of Siphonophyllia samsonensis occur. Associated with these dominant taxa occur colonial and further large solitary taxa (Palaeosmilia, Dibunophyllum). Tizraia and Pareynia are restricted to microbial-dominated buildup facies. Their presence might be strongly controlled by the development of this buildup type, because further occurrences in Algeria, Morocco, and Belgium are all in the same facies. The coral fauna at Jerada is a typical Late Viséan assemblage for the Western European Province. The Eastern Moroccan Meseta may be an important pathway within the province for the connection between the Central Saharan basins and NW Europe. The biostratigraphic ages of the coral fauna partly contradict ages based on carbonate microfossils; the coral ages are slightly older and typical Brigantian coral taxa are absent.  相似文献   

19.
Aim To investigate distributional patterns and derivation of skates in the Australasian realm. Location Australasia. Methods Genus‐group skate taxa were defined for this region for the first time and new systematic information, as well as bathymetric and geographical data, used to identify distribution patterns. Results The extant skate fauna of Australasia (Australia, New Zealand, New Caledonia and adjacent subAntarctic dependencies) is highly diverse and endemic with sixty‐two species from twelve currently recognized, nominal genus‐group taxa. These include the hardnose skate (rajin) groups Anacanthobatis, Amblyraja, Dipturus, Okamejei, Rajella and Leucoraja, and softnose skate (arhynchobatin) genera Arhynchobatis, Bathyraja, Insentiraja, Irolita, Pavoraja and Notoraja. Additional new and currently unrecognized nominal taxa of both specific and supraspecific ranks also occur in the region. The subfamily Arhynchobatinae is particularly speciose in Australasia, and the New Zealand/New Caledonian fauna is dominated by undescribed supraspecific taxa and species. The Australian fauna, although well represented by arhynchobatins, is dominated by Dipturus‐like skates and shows little overlap in species composition with the fauna of New Zealand and New Caledonia. Similarly, these faunas exhibit no overlap with the polar faunas of the Australian subAntarctic dependencies (Heard and Macdonald Islands) to the south. Skates appear to be absent from the Macquarie Ridge at the southern margin of the New Zealand Plateau. Their absence off New Guinea probably reflects inadequate sampling and the subsequent poor knowledge of that region's deepwater fish fauna. Main conclusions Skates appear to have existed in the eastern, Australasian sector of Gondwana before fragmentation in the late Cretaceous. The extant fauna appears to be derived from elements of Gondwanan origin, dispersal from the eastern and western Tethys Sea, and intraregional vicariance speciation.  相似文献   

20.
In bumblebee‐pollinated Cypripedium macranthos var. rebunense, some plants have small labella that do not allow pollinating queens to enter, but they occasionally produce capsules for reasons that remain unclear. We found that after anthesis, the labellum gradually droops, and its width and length (but not height) distinctly increase, eventually producing an elongate and dorsoventrally compressed shape. The rate of increase in labellum size was significantly greater in flowers that initially had a smaller labellum, so that the post‐anthesis changes actually enabled large‐bodied bumblebees to enter those labella. Therefore, we conclude that C. macranthos var. rebunense relied on only bumblebee queens for pollination, irrespective of labellum size at the time of anthesis. Observations of in‐labellum bumblebee behavior suggested that the elongate and dorsoventrally compressed shape and the inclination seemed to result in more predictable and desirable bumblebee movements into the labellum.  相似文献   

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