首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
An association of contemporaneous Jurassic mega- and miospores with reworked Carboniferous mega- and miospores is described from the Lower Lias rocks of northeast Scotland. The assemblage is compared with other accounts of reworked spores in Jurassic sediments. It is suggested that such reworking was particularly common in the Lower Jurassic of northern Europe and that four situations exist in the literature concerning probable cases of reworking: (1) the spores are recognised as reworked; (2) the identity of the spores as Carboniferous species is recognised and the “range” of these species is extended into the Jurassic; (3) the reworked spores are not recognised as such, and are incorrectly assigned to Jurassic genera and species; (4) the spores are recognised as Carboniferous, but their origin is attributed to contamination rather than reworking. In conclusion, the contrasting preservational features exhibited by the reworking and contemporaneous megaspores are discussed and interpreted as the result of differing depositional and postdepositional histories.  相似文献   

2.

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.  相似文献   

3.
Four species of actinosporeans are described from marine oligochaetes (all Tubificidae) from the Great Barrier Reef, Queensland, Australia. They developed in the coelom of the oligochaete and produced spores in groups of eight in the pansporocysts. The new genus Endocapsa is proposed within the family Sphaeractinomyxidae Janiszewska, 1957 on the basis that mature spores have small valve cell processes and non-protruding polar capsules. The type-species, Endocapsa rosulata n. sp., has three valve cell processes, which resemble a rosette, and submerged polar capsules. It infected Heterodrilus cf. keenani from Heron Island and morphologically similar parasites occurred in Thalassodrilides cf. gurwitschi and Heronidrilus sp. from Lizard Island. E. stepheni n. sp. has asymmetrical valve cell processes and submerged polar capsules. It was found in H. cf. keenani and H. queenslandicus from Heron Island. Sphaeractinomyxon leptocapsula n. sp. has thin widely spaced polar capsules and is described from Heronidrilus sp. from Lizard Island. S. ersei Hallett, O'Donoghue & Lester, 1998 infected Tubificidae gen. sp. from Heron Island and S. cf. ersei occurred in Bathydrilus sp., Thalassodrilides cf. gurwitschi and Limnodriloides lateroporus from Lizard Island.  相似文献   

4.
Two ammonites belonging to the genusPictonia Bayle, 1878 (subgenusPachypictonia Schneid, 1940) are described from the Lower Kimmeridgian of the Subbetic of Western Andalusia, this being the first evidence of the presence of this genus in the Mediterranean (Tethydian) Upper Jurassic.  相似文献   

5.
The goshawk Accipiter gentilis has recently been reintroduced into parts of Great Britain. During the course of a study of one population, lesions of stomatitis were observed in 14 young from five broods and all the affected birds died. Postmortem examination of three birds revealed live Trichomonas gallinae in exudate from one, and histological findings consistent with a diagnosis of trichomoniasis were made in this and one other bird. It is suggested that trichomoniasis may be a significant mortality factor in goshawks from Britain.  相似文献   

6.
A new subfamily, Pseudobrieniinae, including the new genus Pseudobrienia and the new species Pseudobrienia rasnitsyni, Kararhynchus jurassicus, and K. gratshevi, are described from the Middle-Late Jurassic of Karatau. K. occiduus Zherikhin et Gratshev, 1993 is redescribed.  相似文献   

7.
The genus Phyllhermannia Berlese, 1916 is redefined. Two main groups of species are postulated within the genus, each being further divided into two subgroups. Known species reviewed completely or in part are: P. dentata, P. bimaculata, P. mollis and P. pulcher . New distribution records are given for the New Zealand species P. foliata, P. forsteri, P. mollis, P. phyllophora and P. rubra , together with a distribution map of all species. Some biogeographical comments are included for the genus. P. africana Balogh, 1958 is redescribed and a new species, P. collofi sp.n., is established. A key to the species of the world is provided.  相似文献   

8.
9.
SUMMARY. There are thirty-one British leptocerid species in nine genera. A key is provided to identify larvae of all species at the final (fifth) instar and many species are also separated at earlier instars. The work is based on British material for all but one species.  相似文献   

10.
The status of the four currently recognised species in the Littorina saxatilis species-complex, i.e. Littorina nigrolineata Gray, L. arcana Hannaford Ellis, L. saxatilis (Olivi) and L. neglecta Bean is reviewed briefly, with notes on their characteristic features and location on the shore. Since the taxonomy of these rough periwinkles has only become stable relatively recently much of the previously published information on distribution is of little or no use. In this paper their distribution around the coastline of England and Wales (with some notes on Scotland) is described and discussed. L. saxatilis is found in a wide range of habitats from exposed peninsulas to estuaries on all shores where there is a suitable rocky or stony substrate; also in salt marsh pools. L. arcana has a more restricted distribution and is notably absent along much of the south English coast, central Cardigan Bay and possibly northern Scotland; it is not found in estuaries. L. nigrolineata has an even more restricted distribution, although it occurs both on exposed coasts and in estuaries; it has only been found by us in one locality on the east coast. L. neglecta is probably fairly widely distributed but we have few details so far. The implications of the different patterns of distribution are discussed.  相似文献   

11.
Summary East of Seefeld/Tyrol the Hauptdolomit facies (Triassic, Norian) is accompanied by an organic-rich intercalation, the Seefeld facies. Three facies were distinguished, which developed within a separate basin within the Hauptdolomit carbonate platform. These facies have been investigated in an environmental and palaeoecological context applying microfacies analysis, palynology, organic petrology, organic geochemistry and stable isotope geochemistry. As the controlling factors of sedimentation, sea level changes are suggested for large scale fluctuations, and climatic changes for variations on a smaller scale. Within the basin facies a μm-scaled rhythm can be observed, which was obviously seasonally controlled. Amajor amount of organic material of the deposit has been produced by microbial activity under anoxic conditions. Causes for the absence of pollen and spores in many black shale deposits are discussed.  相似文献   

12.
The late Jurassic exogyrine oysterNanogyra virgula occurs in fine-grained low-energy sediments of the European epicontinental sea. It is interpreted as having lived cemented to hard substrates during early juvenile stages, but commonly reclining on soft, muddy substrates in the adult stage. This is supported by several morphological adaptations to such a mode of life.  相似文献   

13.
An Early Jurassic (Upper Pliensbachian) gastropod fauna from the Herforder Liasmulde (Herford Lias Syncline) near Bielefeld, Northwest Germany is described. This is one of the first detailed and illustrated reports of Pliensbachian gastropods from this area. Sixteen species are reported. Surface collecting yielded relatively large vetigastropods (pleurotomarioids amd trochomorphs). Bulk samples yielded abundant small caenogastropods (especiallyLevipleura blainvillei andKalchreuthia frankei) and cylindrobullinid opisthobranchs (e.g.Cylindrobullina dornend). These small species are also abundant in the Pliensbachian of South Germany (N Bavaria, Franconia). Therefore, this characteristic Pliensbachian microgastropod assemblage was widespread in Germany and probably also in other comparable marine deposits of Central Europe (e.g. the Paris Basin).   相似文献   

14.
The following species are described, figured and/or recorded from the Great Barrier Reef at Heron Island or Lizard Island, Queensland, with comparative material reported from other areas of the ocean around Australia or New Guinea: Dinurus longisinus (new synonym: D. hippuri) from Seriola lalandi, Heron Island and Coryphaena hippurus, Papua New Guinea; Ectenurus trachuri from Caranx sexfasciatus, Diploprion bifasciatus, Pterocaesio marri, Seriola lalandi and Atherinomorus capricorniensis, Heron Island; Erilepturus hamati (with 25 new synonyms) from Lutjanus carponotatus, Lizard Island, Platycephalus bassensis, Coff's Harbour, NSW, P. fuscus, Coff's Harbour, NSW and Moreton Bay, Queensland, P. endrachtensis, Sillago analis, S. maculata, S. ciliata, Pseudorhombus arsius and Polydactylus sp. from Moreton Bay, Queensland and Lates calcarifer, Darwin, Northern Territory; Tubulovesicula angusticauda from Echeneis naucrates and Lethrinus miniatus, Heron Island and Anguilla reinhardtii, Moreton Bay and Bribie Island, Queensland; Elytrophalloides humerus from Trachinotus botla and T. coppingeri, Heron Island; Lecithochirium kawakawa from Euthynnus affinis Heron Island and Lizard Island: Lecithochirium cirrhiti (new synonyms: L. sammarae, L. nohu) from Sargocentron rubrum, Heron Island; Lecithochirium caesionis from Pterocaesio marri, heron Island; Plerurus digitatus (new synonyms: P. cynoglossi, P. atulis, P. scomberomori) from Plectropomus leopardus, Heron Island, Lutjanus erythropterus, Variola louti, Scomberomorus semifasciatus, Grammatorcynus bicarinatus and Carangoides embureyi, C. gymnostethoides, Lizard Island, Scomberomorus commerson, Heron Island, Lizard Island, New Britain, Papua New Guinea, Point Lookout, Queensland and Moreton Bay, Queensland, Euthynnus affinis Heron Island, Lizard Island and New Britain, Papua New Guinea, Sphyraena barracuda, Heron Island and Lizard Island, Scomberomorus munroi, S. queenslandicus and Saurida undosquamis, Moreton Bay, Queensland and Chirocentrus dorab, Bundaberg, Queensland. The Lecithochirium species-group Cirrhiti is considered indistiguishable from the species-group Lotellae.  相似文献   

15.
16.
Abstract. Eriopeltis varleyi from Wytham in Britain is described as new. The adult female and male are described and all stages are illustrated. Keys are provided for the identification of all known species of Eriopeltis, and to the males of the three species known from Britain. E. varleyi is univoltine and apparently specific to Brachypodiumpinnatum (L.) Beauv. Males and females occur in equal proportions, but many more males were produced when populations were reared under very warm dry conditions in the laboratory. The population studied at Wytham was parasitized by a number of species of chalcid wasps and a chamaemyid fly egg predator.  相似文献   

17.
A new species of Strophingia is described from males and females taken in Dorset and Hampshire. Its separation from Strophingia ericne is discussed, and notes on the host plants and geographical range of the two species are included.  相似文献   

18.
Noel H. Holmgren 《Brittonia》1978,30(3):334-339
Penstemon immanifestus, a new species from the Great Basin, is described and illustrated, and its distribution is mapped. Its relationship to other species of subgenus Penstemon, sect. Coerulei, is discussed.  相似文献   

19.
The karyotype and external morphology of Leptothorax ( Myrafant ) ants, taken from nests at nine ' Leptothorax tuberum ' localities in England and Wales, identifies them all as L. tuberointerruptus. Their karyotype differs in chromosome number and chromosome morphology from the karyotypes of morphologically similar European Leptothorax ( Myrafant ) species including L. tuberum , but matches the karyotype shared by L. tuberointerruptus and L. rougeti. Worker propodeal spine length, and worker propodeal spine shape coupled with worker gaster banding characteristics, distinguish the nest samples from L. rougeti. The presence of L. tuberointerruptus in Britain is therefore confirmed, and the data demonstrate this ant's occurrence throughout the British range attributed to L. tuberum. In the absence of equivalent data identifying L. tuberum as a British species, it may reasonably be assumed that L. tuberointerruptus has been misrecorded as L. tuberum in Britain and that all British mainland records of L. tuberum refer to L. tuberointerruptus. An examination of the syntypes of Stenamma albipennis shows that S. albipennis and L. tuberointerruptus are synonymous, and that L. albipennis is the senior name. It follows that L. albipennis is a scarce British ant of 'Notable B' conservation status. A taxonomic synopsis for L. albipennis is given.  相似文献   

20.
SUMMARY. 1. Prior to 1975 Dugesia tigrina , an Americati immigrant triclad, was known from only a few flowing water sites in Great Britain. Since then it has been found in a large number of lowland rivers and canals in England and Wales, and in 1985 it was reported from the lower reaches of the River Tweed in Scotland.
2. This note gives the recorded distribution of D. tigrina up to the end of 1985 (115 10 km squares now occupied) and summarizes the environmental conditions at a subset of twenty-five sites where D. tigrina occurs.
3. Information on the native triclads at sites recently colonized by D. tigrina is used as a basis for speculating on the rivers most vulnerable to the future spread of this species.
4. Possible methods of dispersal of D. tigrina and the features which make it a successful colonist are discussed.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号