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1.
A distinctive shallow–burrowing bivalve with an elongate rostrum, common in the British Middle Jurassic, is frequently referred to as Cuspidaria ibbetsoni (Morris, 1853) and as such is recognised as one of the earliest members of the anomalodesmatan family Cuspidariidae. Since modern cuspidariids are highly specialised bivalves and are voracious carnivores in the deep sea, whereas C. ibbetsoni is prevalent in brackish–water facies, questions have been raised over its true affinities. We have investigated new and pre–existing material of C. ibbetsoni , and have concentrated on shell microstructure, morphology, and musculature. Our findings suggest that the inequivalve shell is composed of crossed–lamellar aragonite rather than either homogeneous or prismato–nacreous structures. It also lacks the complex musculature associated with the raptorial siphon of the predatory septibranchs. These characters suggest that C. ibbetsoni should more properly be placed within the myoid family Corbulidae and a new genus, Rostrocorbula , has been erected to accommodate it. It has also been necessary to establish a neotype. The significance of this familial redesignation to our understanding of the evolution of carnivory within the Bivalvia is discussed. 相似文献
2.
Xiao Tan David L. Dilcher Hongshan Wang Yi Zhang Yu-Ling Na Tao Li Yun-Feng Li Chun-Lin Sun 《Palaeoworld》2018,27(3):360-373
Yanliaoa is a common fossil in the Middle Jurassic of western Liaoning, eastern Inner Mongolia and northern Hebei Province, China. It is an important element of the Yanliao biota. The genus was established by Pan in 1977 for fossil plants from the Middle Jurassic Haifanggou Formation in Xiasanjiaochengzi, western Liaoning Province, and in present paper, the genus Yanliaoa is studied based on new material. Pan never designated a type specimen and his fossil material cannot be located. We designate a type specimen here for Yanliaoa, so that the genus name Yanliaoa remains valid. Yanliaoa sinensis Pan emend. Tan et al., is found in the same locality and formation as the lost specimens, Y. sinensis of Pan, 1977. Yanliaoa daohugouensis n. sp., a new species with epidermal anatomy, is from the Middle Jurassic Daohugou, Inner Mongolia. A holotype is also selected from the new material for this new species. Characters of the leafy shoots and ovulate cones of Yanliaoa are emended. The epidermal anatomy of this genus is described for the first time. Compared with other extant and extinct species of Cupressaceae s. l., the current species can be distinguished from any known species both by the leafy shoot characters and its epidermal anatomy. It further indicates that Yanliaoa is an extinct and endemic conifer found in the Middle Jurassic of northeastern China. 相似文献
3.
The Geonemertes problem (Nemertea) 总被引:2,自引:0,他引:2
A new genus of monostiliferous hoplonemerteans, Pantinonemertes gen. nov., provides evidence for the separate evolution of terrestrial nemerteans. The genus is established for two new species found in Australia, P. enalios sp. nov., an intertidal form, and P. winsori sp. nov., which lives in fallen timber in the supralittoral brackish water regions of mangrove swamps. One only of the known species of land nemerteans, Geonemertes agricola from Bermuda, closely resembles these two species morphologically and is transferred to the new genus as Pantinonemertes agricola .
A re-examination of all the known species of Geonemertes has shown that two major groups can be distinguished on the basis of morphological characters. In one group the rhynchocoel musculature is in two distinct layers, a frontal organ is present, the mid-dorsal blood vessel has a single vascular plug, and the flame cells are binucleate and reinforced with cuticular support bars. It comprises the genus Pantinonemertes gen, nov, and the Pelaensis or Indopacific group of terrestrial nemerteans, for which the generic name Geonemertes is retained. In the second major group the rhynchocoel musculature is composed of interwoven longitudinal and circular fibres, there is no frontal organ, the mid-dorsal blood vessel bears two vascular plugs, and the flame cells are mononucleate and lack support bars. Five genera, three of which are new, are distinguished in this group. Australian species are united in the genus Argonemertes gen. nov., and New Zealand forms comprise the genus Antiponemertes gen. nov., while Acteonemertes bathamae from New Zealand and the Auckland and Ocean Islands remains in a separate genus. Geonemertes nightingaleensis is transferred to a new genus, Katechonemertes gen. nov., and for Geonemertes chalicophora a previously used generic name, Leptonemertes , is adopted.
A key to the terrestrial, brackish-water and marine nemertean species described in the present paper is provided. 相似文献
A re-examination of all the known species of Geonemertes has shown that two major groups can be distinguished on the basis of morphological characters. In one group the rhynchocoel musculature is in two distinct layers, a frontal organ is present, the mid-dorsal blood vessel has a single vascular plug, and the flame cells are binucleate and reinforced with cuticular support bars. It comprises the genus Pantinonemertes gen, nov, and the Pelaensis or Indopacific group of terrestrial nemerteans, for which the generic name Geonemertes is retained. In the second major group the rhynchocoel musculature is composed of interwoven longitudinal and circular fibres, there is no frontal organ, the mid-dorsal blood vessel bears two vascular plugs, and the flame cells are mononucleate and lack support bars. Five genera, three of which are new, are distinguished in this group. Australian species are united in the genus Argonemertes gen. nov., and New Zealand forms comprise the genus Antiponemertes gen. nov., while Acteonemertes bathamae from New Zealand and the Auckland and Ocean Islands remains in a separate genus. Geonemertes nightingaleensis is transferred to a new genus, Katechonemertes gen. nov., and for Geonemertes chalicophora a previously used generic name, Leptonemertes , is adopted.
A key to the terrestrial, brackish-water and marine nemertean species described in the present paper is provided. 相似文献
4.
Nikolaus Malchus 《Pal?ontologische Zeitschrift》2000,74(3):239-246
Post-larval and larval shells ofJuranomia calcibyssata from the Bathonian to Callovian of Poland and RecentAnomia membranacea from the Mediterranean are described and compared to other fossil and Recent members of the family Anomüdae. The stratigraphic
range of the monospecific genusJuranomia, which, up to now, was only known from the Kimmeridgian, can be extended to include the Lower Bathonian. The state of preservation
of the fossil species allows recognition of an internal aragonitic, branching and complex cross-lamellar shell layer in the
post-larval left valve, which previous studies could only assume to be present.Anomia membranacea is a member of theA. ephippium lineage as proved, among other characters, by the presence of an outer calcitic prismatic layer in its right valve. It possesses
an anterior pedal retractor in the left valve, which, in the original discussion of the phylogenetic affinities ofJuranomia, was thought to be lacking in species ofAnomia. Consequently, the generaJuranomia andAnomia only differ in two important shell characters: closeness or distance between the three central muscles and thickness of the
inner aragonitic shell layer of the left valve.
Larval shells ofJuranomia are similar to those of Recent anomiids in shape, size, the presence of a byssal notch in the right valve, and an external
sinus and internal shelly process in the left valve. The last three features are parts of a single character which is considered
as an autapomorphy of the stem species of the Anomiiudae. The small P I size ofJuranomia calcibyssata suggests a purely planktic-planktotrophic development and thus, high potential of dispersal, just as its modern counterparts.
Irrespective of the general similarity in shell size, the mean dimensions of the P II are likely species-specific. 相似文献
5.
ANATOMY OF SOME INDO-PACIFIC ELYSIIDAE (OPISTHOBRANCHIA: SACOGLOSSA (=ASCOGLOSSA)), WITH A DISCUSSION OF THE GENERIC DIVISION AND PHYLOGENY 总被引:1,自引:0,他引:1
The Elysiidae is the largest family of Sacoglossa (=Ascoglossa)(Mollusca, Opisthobranchia). The Indo-Pacific fauna containsabout 65 species presently referred to the genus Elysia. Almostnothing is known about the internal anatomy of these animals.In the present study the internal anatomy, particularly thepharyngeal musculature, morphology of radularteeth, and reproductivesystems, of 12 Indo-Pacific elysiids is investigated. Also,the internal anatomy of the Mediterranean type species of thegenera Elysia and Thuridilla is described. On this basis, thevalidity of the genera Elysia, Thuridilla, Elysiella and Pattyclaya,is confirmed. Also, the genus Placobranchus is transferred tothe Elysiidae. phylogenetically important characters are identifiedand phylogenetic relationships within the family are discussed. (Received 10 April 1991; accepted 28 December 1991) 相似文献
6.
DIETER MEISCHNER 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1968,1(2):156-174
An adult Ceratites semipartitus encrusted by epifaunal Placunopsis ostracina is described. The epizoans are orientated in relation to the slope of the substratum and according to their time of attachment to the ammonoid shell. Geometrical analysis of the orientation leads to the following conclusions: (1) During and after the growth of the last whorl, several, probably 4, swarms of larvae of Placunopsis settled upon the Ceratites specimen. (2) The dead body was for some time kept upright, the living chamber showing upwards. During this time, larvae of Placunopsis became attached again. (3) The ammonoid shell was then laid down, its left flank in contact with the sediment. In this position it was for the last time settled upon by Placunopsis which died whilst juvenile.
Provided that the phases of attachment corresponded to annual spawning periods of Placunopsis , the last whorl of the Ceratites was formed with decreasing velocity of growth within about 4 years.
Placunopsis became attached with its right valve, the posterior end of the body showing upwards, and the direction of growth being declined from the vertical by 65°. Placunopsis either preferred to settle within a distinct zone of the living chamber of the ammonoid close to the lowermost part of the shell or was able to grow up here only. Ceratites semipartitus was therefore probably nectonic.
Both the host and the epizoan were influenced to their disadvantage by their fatal partnership. A relationship of this kind therefore should not be called a symbiosis. 相似文献
Provided that the phases of attachment corresponded to annual spawning periods of Placunopsis , the last whorl of the Ceratites was formed with decreasing velocity of growth within about 4 years.
Placunopsis became attached with its right valve, the posterior end of the body showing upwards, and the direction of growth being declined from the vertical by 65°. Placunopsis either preferred to settle within a distinct zone of the living chamber of the ammonoid close to the lowermost part of the shell or was able to grow up here only. Ceratites semipartitus was therefore probably nectonic.
Both the host and the epizoan were influenced to their disadvantage by their fatal partnership. A relationship of this kind therefore should not be called a symbiosis. 相似文献
7.
8.
Podocarpophyllum Gomolitzky is studied in detail from the type locality Angren (Uzbekistan, Middle Jurassic). Emended diagnoses of the genus and its type species P. singulare Gomolitzky are provided. For the first time, members of the genus are reported from the Lower Jurassic of the Mangyshlak Peninsula (western Kazakhstan), where P. kazachstanicum sp. nov. is described, and from the Middle Jurassic of the eastern Ural Mountains, where P. mesozoicum (Kiritchkova) comb. nov. is established. The epidermal morphology of the genus Podocarpophyllum is compared with that of fossil and modern members of the Podocarpaceae. 相似文献
9.
Microplana termitophaga has been observed feeding on termites in Harare, Zimbabwe. In small specimens the pharynx is about two-thirds of the way along the body, but in large specimens the pharynx is only one quarter of the way along the body. Details of the subepidermal musculature of specimens from Kenya and Zimbabwe are described which confirm the previously uncertain assignment of the species to the subfamily Microplaninae. Sexually mature specimens are found towards the end of the wet season in Zimbabwe. The anatomy of the reproductive system is described. The gonopore is about two-thirds of the way along the body in mature specimens, but sexual maturity seems not to be related simply to size. There is a genito-intestinal duct which confirms that the species is of the genus Microplana. 相似文献
10.
The heteromorph ammonite Pravitoceras sigmoidale from the Upper Cretaceous Seidan Formation (Izumi Group) in south‐west Japan is frequently encrusted by sessile anomiid bivalves. Fossils of P. sigmoidale with anomiids are often concentrated at the top of or just above turbidite sandstones. Projecting retroversal hooks and apertures of P. sigmoidale are usually intact, and some individuals are associated with jaw apparatuses near apertures. Anomiids are found on both sides and ventral peripheries of P. sigmoidale conchs, attached predominantly to body chambers. These modes of occurrence suggest that the encrustation by anomiids occurred not on post‐mortem floating or sunken carcasses but on live conchs and that these organisms were rapidly buried by turbidity current deposits shortly after death. Attachment to both flanks and ventral peripheries of the retroversal hooks may indicate that at least adult individuals of P. sigmoidale did not lie on the sea floor and did not drag their body chambers. It is suggested that fully mature individuals of this ammonite species lived for a long period of time after having formed the retroversal hook because a few generations of anomiids have colonized a single body chamber. Such colonization by anomiids is also observed on Didymoceras awajiense, which is considered to be the closely related ancestral species of P. sigmoidale. This anomiid–heteromorph ammonite commensal relationship might continue to persist in descendants during the course of evolution of these heteromorph ammonites. 相似文献
11.
The macromorphology and epidermal anatomy of three Late Carboniferous-Early Permian pteridosperm species, conventionally assigned to the form-genus Pseudomariopteris Danzé-Corsin, are described from the Stephanian of the Blanzy-Montceau Basin (Central France). The generic diagnosis of Pseudomariopteris is emended, and P. busquetii is designated as the type species of the genus. The combination P. cordato-ovata (Weiss) Gillespie et al. is validated to replace the illegitimate name P. ribeyronii (Zeiller) Danzé-Corsin. The species diagnoses of P. busquetii and P. cordato-ovata are emended. On the basis of its epidermal anatomy, P. paleaui, another species orininally described from Central France, is transferred to the newly established genus Helenopteris Krings et Kerp, and the new combination Helenopteris paleaui is introduced. Lectotypes of P. busquetii and H. paleaui are selected. In addition, specimens from other basins are (re-)examined and illustrated. Seeds attached to a P. busquetii specimen suggest a callistophytalean relationship for Pseudomariopteris. Compression fossils and cuticles of Pseudomariopteris and Helenopteris are interpreted in terms of palaeoecology: Pseudomariopteris busquetii and P. cordato-ovata had climbing/scrambling growth habits; specialized climber hooks can be demonstrated for both species, either in compression or in cuticular preservation. Although the growth habit of H. paleaui is not yet entirely clear, the size of its fronds suggests that this taxon most probably was also a scrambler/climber. Finally, based on epidermal features, a tentative reconstruction of stages of the pinnule ontogeny of H. paleaui is provided. 相似文献
12.
鳞果星蕨属是从星蕨属中划分出来的,其孢子囊群上幼时覆盖着近无柄的鳞片状隔丝。本文在
研究星蕨亚科植物标本和野外考察的基础上,结合解剖学、孢粉学、生态学和植物地理学资料,对鳞果星蕨属植物作了修订。承认该属的独立性,并研究了有关种类的变异幅度,将星蕨属中有盾状隔丝的种类归入本属,承认鳞果星蕨和云南鳞果星蕨两个种。 相似文献
13.
The genus Lepidomicrosorum was separated from Microsorum Link by Ching
and Shing in 1983. It is characterized by minute scattered sori covered with peltate and subsessile paraphyses when young. Tagawa detected that Polypodium subhastatum Baker, the
type of this new genus, has this kind of paraphyses and thus transferred this species to
Neocheiropteris Christ in 1952, a genus with divided lamina. During our study of the Microsoroideae, a revision of Lepidomicrosorum from China and neighboring regions is made on
the basis of field and herbarium observation and evidence from anatomy, spore morphology,
ecology, and distribution. Lepidomicrosorum is recognized as an independent genus and the
demarcation line of its species is reconfirmed. Species with peltate scale-like paraphyses in
Microsorum were transferred to Lepidomicrosorum. As a result, two species are recognized
in this species, i.e.L.buergerianum (Miq.) Ching et Shing and L. hymenodes (Kunze)L. Shi et X. C. Zhang. 相似文献
14.
Feeding ecology of the deep‐bodied fish Dapedium (Actinopterygii,Neopterygii) from the Sinemurian of Dorset,England
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Fiann M. Smithwick 《Palaeontology》2015,58(2):293-311
Reconstructing the feeding ecology of fossil fishes can be difficult, but new mechanical approaches enable reasonably reliable inferences by comparison with living forms. Here, the feeding ecology of one of the most iconic and abundant actinopterygians of the Early Jurassic, Dapedium, is explored through detailed anatomical study and functional analyses of jaw mechanics. Mathematical models derived from modern teleost functional morphology are applied, to ascertain the transmission of force through the jaws of Dapedium. A number of features not previously identified in the genus are described, and the dentition is described in full for the first time. The analysis of the functional morphology of Dapedium, in combination with its jaw anatomy and dentition, indicates that the genus was well adapted to a durophagous feeding habit, although indirect evidence suggests a more generalist feeding mode. Being a generalist durophage may explain the success of the genus in the aftermath of the end‐Triassic extinction event and its radiation in the Early Jurassic, as indicated by the ubiquity of Dapedium fossils throughout the Lower Lias. 相似文献
15.
Surajit Roy Yan Liu John Patrick Kociolek Rex L. Lowe Balasubramanian Karthick 《Phycological Research》2020,68(1):80-89
A new triundulate naviculoid diatom genus is described from the Western Ghats of Peninsular India and Hainan Province, China. The new taxon, Kulikovskiyia gen. nov. has robust conical spines along its margin and at the apices and the external valve face has longitudinally‐oriented siliceous slat system extending the length of the valve. The external distal raphe ends bifurcate and terminates on the valve face. There appear to be superficial similarities between this Asian genus and species and Playaensis, a genus comprised of two species found only in the western USA. The systematic position of Kulikovskiyia is discussed, and other than noting its similarities to other biraphid naviculoid diatoms due to symmetry features and the position of the raphe, we are uncertain about its systematic placement at finer levels of classification. 相似文献
16.
SHIN‐ICHI SANO PETER W. SKELTON MEGUMI WATARAI YASUHIRO IBA YASUO KONDO YUICHIRO SATO 《Palaeontology》2012,55(4):843-851
Abstract: Pachytraga Paquier, 1900, the stratigraphically oldest genus of caprinine caprinid rudist, was previously known from only two chronospecies from a single lineage, that is the Hauterivian P. tubiconcha Astre, 1961 and the early Aptian P. paradoxa (Pictet and Campiche, 1869). Here, a new species, Pachytraga? tanakahitoshii, is erected on the basis of isolated left valves recovered from the Osaka and Sanchu areas, south‐west Japan. This species has a moderate shell size (antero‐posterior commissural diameter c. 30 mm), and its left valve is characterized by at least one possibly autapomorphic character (narrow anterior myophore, inclined inwards), as well as a mosaic of primitive (single longitudinal carina developed on the anterior side) and derived (simple marginal canals in the antero‐dorsal valve margin) characters of Mediterranean and Middle East Tethyan Pachytraga. The Japanese Pachytraga? represents the first probable record of this genus outside the Mediterranean/Middle Eastern Tethyan province, and its early Barremian age partly fills the ‘gap’ in its previously known stratigraphical record, although the evolutionary relationship of the Japanese form with Mediterranean and Middle East Tethyan Pachytraga remains unsolved. However, the discovery of early Barremian Pachytraga? in Japan indicates that the evolutionary history of the genus is more complex than previously thought and should thus be discussed in a broader palaeogeographical context that must now include the Pacific. 相似文献
17.
In the molluscan class Solenogastres, different types of foregut glands vary in number, structure, and location within the foregut. The present article describes their anatomy and cytology and intends to clarify their confused terminology. Pharyngeal glands, esophageal glands, and the more complex dorsal and ventrolateral foregut glands can be distinguished. The ventrolateral foregut glands (ventral foregut glandular organs, ventral salivary glands of auct.), in the literature subdivided previously into four types, are revisited here in the context of current vertebrate gland terminology. The results of recent investigations are added to earlier ones, and a classification system for these multicellular glands is proposed. This system is based on cytological characters of glandular cells (intra- or extraepithelial), characters of the associated musculature (inner or outer musculature), location of the gland relative to the pharynx epithelium (endoepithelial or exoepithelial), characters of the gland openings (paired or unpaired), morphology of the gland duct (simple or branched), and some additional features like the arrangement of glandular cells along the gland ducts. Gross morphology and anatomy of ventrolateral foregut glands constitute useful taxonomic characters in determining higher taxa (family level), and finer details of the anatomy and cytology are useful in determining lower levels (genus and species). Possible pathways for the evolution of the different gland types of Solenogastres in relation to foregut glands present in the other molluscan clades are presented. The importance of ventrolateral foregut gland characters for phylogenetic considerations within the Solenogastres is discussed. 相似文献
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19.
A crocodilian jaw fragment from the Jurassicof Thailand is referred to a new species of the genus SunosuchusYoung,, 1948, S. thailandicus.. The genus Sunosuchus,, which is interpreted here as belonging to the family Goniopholididae (Mesosuchia),, was previously known only from the continental Jurassic of north-central China. The occurrence of this freshwater crocodilian in the Khorat Group of Thailand provides evidence that, whatever its previous palaeogeographical history may have been, by Jurassic times South-East Asia was part of Laurasia. 相似文献
20.