The Middle Jurassic Bivalve 'Cuspidaria'Ibbetsoni: A Corbulid Not A Septibranch

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.     

Yanliaoa, an extinct genus of Cupressaceae s. l. from the Middle Jurassic,northeastern China

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.     

The Geonemertes problem (Nemertea)

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.     

Post-larval and larval shells ofJuranomia Fürsich & Werner 1989, andAnomia Linnaeus 1758 (Anomüdae, Bivalvia)

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.     

ANATOMY OF SOME INDO-PACIFIC ELYSIIDAE (OPISTHOBRANCHIA: SACOGLOSSA (=ASCOGLOSSA)), WITH A DISCUSSION OF THE GENERIC DIVISION AND PHYLOGENY

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)     

PERNICIÖSE EPÖKIE VON PLACUNOPSIS AUF CERATITES

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.     

獐牙菜属植物花蜜腺形态及解剖学

在扫描电镜下观察了獐牙菜属Swertia L.10组30种植物花蜜腺的数目,位置,形态和附属物等特征;同时还利用光镜对各组代表种的蜜腺结构进行了解剖学观察。结果表明獐牙菜属花蜜腺外部形态多种多,但在组与组之间无明显间断,演化序列呈梯度变化;内部结构基本相同,为不具维管束的结构蜜腺,且均为淀粉型蜜腺。因此,从花蜜腺的角度不支持将獐牙菜属划分为小属的观点,同时,还结合其它证据讨论了花蜜腺特征的演化趋势。     

A new species and a new combination of the Mesozoic genus Podocarpophyllum Gomolitzky (Coniferales)

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.     

The anatomy of Microplana termitophaga from Zimbabwe and Kenya: confirmation of the subfamily and genus

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.     

Commensal anomiid bivalves on Late Cretaceous heteromorph ammonites from south‐west Japan

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.     

A contribution to the knowledge of the pteridosperm genera Pseudomariopteris Danzé-Corsin nov. emend. and Helenopteris nov. gen

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.     

中国及邻近地区鳞果星蕨属的分类研究

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。     

Taxonomic studies of the fern genus Lepidomicrosorum Ching et Shing (Polypodiaceae) from China and neighboring regions

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.     

Feeding ecology of the deep‐bodied fish Dapedium (Actinopterygii,Neopterygii) from the Sinemurian of Dorset,England

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.     

Kulikovskiyia gen. nov. (Bacillariophyceae) from the lateritic rock pools of the Western Ghats,India and from Hainan Province,China

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.     

First record of an Early Barremian caprinid rudist from Japan – implications for the palaeobiogeography of the Caprinidae (Bivalvia)

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.     

Foregut glands of Solenogastres (mollusca): anatomy and revised terminology

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.     

A new crocodilianfrom the Jurassic of Thailand, Sunosuchus thailandicus n. sp. (Mesosuchia,Goniopholididae)), and the palaeogeographical history of South-East Asia in the Mesozoic

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.     

First diagnostic marine reptile remains from the aalenian (middle jurassic): a new ichthyosaur from southwestern Germany

Background

The Middle Jurassic was a critical time in the evolutionary history of ichthyosaurs. During this time interval, the diverse, well-studied faunas of the Lower Jurassic were entirely replaced by ophthalmosaurids, a new group that arose sometime prior to the Aalenian-Bajocian boundary and by the latest middle Jurassic comprised the only surviving group of ichthyosaurs. Thus, the Middle Jurassic Aalenian-Bathonian interval (176–165 million years ago) comprises the time frame during which ophthalmosaurids not only originated but also achieved taxonomic dominance. However, diagnostic ichthyosaur remains have been described previously from only a single locality from this interval, from the Bajocian of Argentina.

Methodology/Principal Findings

In this paper, we describe a new species of ichthyosaur based on a partial articulated specimen from the Middle Jurassic of southwestern Germany. This specimen was recovered from the Opalinuston Formation (early Aalenian) and is referable to Stenopterygius aaleniensis sp. nov. reflecting features of the skull and forefin. The genus Stenopterygius is diverse and abundant in the Lower Jurassic of Europe, but its presence has not previously been confirmed in younger (Middle Jurassic) rocks from the northern hemisphere.

Conclusions/Significance

This specimen represents the only diagnostic ichthyosaur remains reported from the Aalenian. It bears numerous similarities in size and in morphology to the Lower Jurassic species of the genus Stenopterygius and provides additional evidence that the major ecological changes hypothesized to have occurred at the end of the Toarcian took place sometime after this point and most likely did not occur suddenly. There is currently no evidence for the presence of ophthalmosaurids in the northern hemisphere during the Aalenian-Bathonian interval.