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.
2.
A proximal humerus fragment referred to as Azhdarchidae indet. from the Rybushka Formation (Upper Cretaceous, Lower Campanian) of the Beloe Ozero locality in Saratov Region is described. The proximal articular surface is not saddle-shaped, has a weakly convex profile in the frontal section. The most posteriorly projecting part of the proximal articular surface is displaced ventrally. A large pneumatic foramen is located on the anterior surface ventral to the base of deltopectoral crest and close to the proximal articular surface. The humeral head is slightly declined from the diaphysis and only slightly overhangs the diaphysis posteriorly. This proximal humerus fragment possibly belongs to Volgadraco bogolubovi Averianov, Arkhangelsky et Pervushov, 2008, described from the Rybushka Formation of the Shirokii Karamysh 2 locality in Saratov Region.  相似文献   

3.
Fabien Knoll 《Geobios》2002,35(5):595
A new ornithischian skull from the Elliot Formation of southern Africa is described. The specimen is compared in detail with the fabrosaurid Lesothosaurus diagnosticus. It actually shares many characters with specimens of the syntypes of this species or specimens referred to it. It is nevertheless not identical to any of these specimens and it is, moreover, remarkably larger than them. The possibility of attributing this specimen to a so far undescribed ‘large fabrosaur’ from the same formation is discussed. It is concluded that the specimen in question in this paper, while being ascribable to the genus Lesothosaurus, cannot be determined to a specific level until the existence of two fabrosaurid species in the ‘Stormberg Group’ is demonstrated and their range of morphological and size variation is properly appraised.  相似文献   

4.
Abstract: Complete skulls of giant marine reptiles of the Late Jurassic are rare, and so the discovery of the 1.8‐m‐long skull of a pliosaur from the Kimmeridge Clay Formation (Kimmeridgian) of Westbury, Wiltshire, UK, is an important find. The specimen shows most of the cranial and mandibular anatomy, as well as a series of pathological conditions. It was previously referred to Pliosaurus brachyspondylus, but it can be referred reliably only to the genus Pliosaurus, because species within the genus are currently in need of review. The new specimen, together with another from the same locality, also referred to P. brachyspondylus, will be crucial in that systematic revision, and it is likely that the genus Pliosaurus will be found to include several genera. The two Westbury Pliosaurus specimens share many features, including the form of the teeth, but marked differences in the snout and parietal crest suggest sexual dimorphism; the present specimen is probably female. The large size of the animal, the extent of sutural fusion and the pathologies suggest this is an ageing individual. An erosive arthrotic condition of the articular glenoids led to prolonged jaw misalignment, generating a suite of associated bone and dental pathologies. Further damage to the jaw joint may have been the cause of death.  相似文献   

5.
6.
Late Jurassic Mammals from Tendaguru, Tanzania, East Africa   总被引:1,自引:0,他引:1  
Records of Mesozoic mammals are extremely rare in Africa. The only previous record from the Upper Jurassic of Africa is a fragmentary mandible without teeth of Brancatherulum tendagurense. Here I report the discovery of two new mammals from the Upper Jurassic of Tendaguru, Tanzania. The fossils were recovered from the Middle Saurian Bed of the Tendaguru Series. A lower molar of a triconodontid mammal is described as Tendagurodon janenschi gen. et sp. nov., and a fragmentary dentary of a eupantothere as Tendagurutherium dietrichi gen. et sp. nov. The eupantothere in particular contributes to documenting the evolution of mammals during the Mesozoic. The posterior portion of the mandible of Tendagurutherium dietrichi gen. et sp. nov. shows that the angular (tympanic) bone was not yet completely separated from the dentary, a previously undocumented stage of eupantotherian middle ear evolution.  相似文献   

7.
The genus Ctemogenys was originally described as a lizard on the basis of isolated jaw fragments from the Upper Jurassic deposits of Como Bluff, Wyoming. The discovery of new material from a Middle Jurassic locality at Kirtlington, Oxfordshire, showed that Cteniogenys was not a lizard, but an early choristodere. The skull is represented by a collection of isolated bones, associated on the basis of fit and dermal sculpture pattern. The bones are here described and compared with those of the Late Cretaceous and Palaeocene choristoderes Champsosaurus and Simoedosaurus. Allowing for the much smaller size of the Middle Jurassic form, there is a close correspondence between the isolated bones of the three genera. Comparison with known choristoderes, based on an analysis of 53 derived character states, suggests that Ctemogenys is the most primitive of known genera. In general, the character states shared by all choristoderes support recent analyses which conclude that choristoderes arc derived from archosauromorph diapsids, not lepidosauromorphs as once thought. At Kirtlington, Cteniogenys forms part of a diverse microvertebrate assemblage including amiids, sharks, frogs, salamanders, lizards, mammals, crocodiles, pterosaurs, turtles and small dinosaurs.  相似文献   

8.
Abstract: The exquisitely preserved holotype of the pliosaur ‘Rhomaleosaurusvictor (SMNS 12478) is described from the Toarcian Posidonien‐Schiefer (Upper Lias, Lower Jurassic) of Holzmaden (Baden‐Württemberg), Germany. The specimen presents a novel combination of synapomorphies and unique morphometric proportions separating it from Rhomaleosaurus sensu stricto and warranting the erection of a new genus, Meyerasaurus gen. nov. Historically, the name ‘Thaumatosaurus’ has been interchangeable with Rhomaleosaurus and is frequently associated with SMNS 12478 in the literature. However, this is an invalid taxon and cannot be reinstated. The anatomy of Meyerasaurus victor is compared in detail with other pliosaurs, and its taxonomic affinity is reviewed. M. victor belongs to the family Rhomaleosauridae and shares several anatomical characters with Rhomaleosaurus including a short and robust premaxillary rostrum (length‐to‐width ratio c. 1.0), parallel premaxilla–maxilla sutures anterior to the nares, vomers contacting the maxillae posterior to the internal nares, and c. 28 cervical vertebrae minus the atlas–axis. The known geographical distribution of Rhomaleosaurus, which previously extended across the German and English palaeobiogeographical zones, is reduced to the English zone as a consequence of the referral of SMNS 12478 to a new genus. This is significant because it contributes to an ongoing trend of increasing generic separation between the German and English zones, while increasing the generic diversity within the German zone itself.  相似文献   

9.
To date, bivalve calcitic plates which cover the outer chitinous lamella of the lower jaws of Jurassic and Cretaceous ammonoids (aptychi sensu stricto) have been classified into several morphotypes (form genera) based on shape, surface sculpture and internal microstructure. However, previous works on aptychi microstructure focused mainly on thick morphotypes (e.g. Laevaptychus and Lamellaptychus), whereas little was investigated for thin Praestriaptychi. In this study, the microstructure of Praestriaptychi of Upper Oxfordian Perisphinctes and of recently discovered aptychi of aspidoceratid microconch Mirosphinctes (both belonging to the superfamily Perisphinctoidea) is described. These aptychi are compared with Laevaptychi of Upper Oxfordian macroconchs Euaspidoceras (a dimorphic counterpart of Mirosphinctes). This study demonstrated that the aptychi of Perisphinctes and Mirosphinctes differ from each other and from Laevaptychi in their microstructure, number of calcitic layers and in growth patterns. The aptychi of both aspidoceratid dimorphs are similar in terms of growth pattern, but differ in microstructure and the number of calcitic layers. Neither aptychi of Perisphinctes nor of Mirosphinctes have a tubular layer with a honeycomb surface pattern, which is typical for Laevaptychus. This indicates that aptychi were extremely diverse and their microstructure varied significantly not only within the superfamily, but even within a dimorphic pair of aspidoceratid ammonites. A lack of a tubular layer in Praestriaptychus indicates that it developed independently in Lamellaptychus of Haploceratoidea and Laevaptychus of Aspidoceratidae.  相似文献   

10.
A new species of ornithischian dinosaur ( Lycorhinus consors sp. nov.) is established on a skull from the Upper Triassic Red Beds of Lesotho. This ornithischian is assigned to the family Heterodontosauridae of the suborder Ornithopoda. The dinosaurs of the family Heterodonto-sauridae are reviewed: Geranosaurus atavus Broom (1911) is considered a nomendubium and the genus name Heterodontosaurus Crompton & Charig (1962) is held to be a junior synonym for Lycorhinus Haughton (1924).
Functional and palaeoecological implications of the heterodontosaurid dentition are discussed. The pattern of tooth wear may reflect a highly specialized jaw action which involved protraction and retraction of the mandible to produce a grinding effect between upper and lower cheek teeth. Lycorhinus consors is presumed to be a female heterodontosaurid because it differs from all other heterodontosaurids in lacking caniniform tusks. It is suggested that the tusks of heterodontosaurids were functionally analogous to those of tayassuids and tragulids and that they were employed as weapons for intra-specific combat and defence. Dental peculiarities indicate that tooth replacement processes were suppressed in heterodontosaurids; replacement of the teeth seems to have been restricted to a brief period each year (presumably when heterodontosaurids underwent aestivation or hibernation).
A new diagnosis is formulated for the family Heterodontosauridae. The relationships of early ornithopod dinosaurs are briefly reviewed and a new classification is proposed. Ten families of ornithopod dinosaurs are recognized; these are ranked in two grades-one (named Dolichopoda) representing the conservative main stem of the ornithischian phylogenetic tree and the other (named Brachypoda) comprising the several more advanced lines of ornithopod evolution.  相似文献   

11.
12.
A new lacewing species, Leptolingia shartegica sp. nov., (Grammolingiidae), from the Upper Jurassic of the Mongolian Shar-Teg locality is described.  相似文献   

13.
Two new lacewing species, Prohemerobius minor sp. nov. (Prohemerobiidae) and Sogjuta shartegica sp. nov. (Osmylidae), are described from Upper Jurassic deposits of the Mongolian locality Shar-Teg.  相似文献   

14.
Three new genera and five new species of osmylid lacewings are described from the locality Karatau (Kazakhstan, Upper Jurassic): Jurosmylus parvulus sp. nov. (Protosmylinae), Ensiosmylus acutus gen. et sp. nov. (Spilosmylinae), Kolbasinella elongata gen. et sp. nov. (Gumillinae), Arbusella bella gen. et sp. nov. and Jurakempynus arcanus sp. nov. (Kempyninae). Another new osmylid species (Jurakempynus sublimis sp. nov.) is described from the Upper Jurassic of Mongolia (Shar-Teg locality). The quantitative compositions of the osmylid faunas of Karatau and Shar-Teg are discussed.  相似文献   

15.
The taxonomy of the Late Jurassic pterodactyloid pterosaur Pterodactylus scolopaciceps Meyer, 1860 from the Solnhofen Limestone Formation of Bavaria, Germany is reviewed. Its nomenclatural history is long and complex, having been synonymised with both P. kochi (Wagner, 1837), and P. antiquus (Sömmerring, 1812). The majority of pterosaur species from the Solnhofen Limestone, including P. scolopaciceps are represented by juveniles. Consequently, specimens can appear remarkably similar due to juvenile characteristics detracting from taxonomic differences that are exaggerated in later ontogeny. Previous morphological and morphometric analyses have failed to separate species or even genera due to this problem, and as a result many species have been subsumed into a single taxon. A hypodigm for P. scolopaciceps, comprising of the holotype (BSP AS V 29 a/b) and material Broili referred to the taxon is described. P. scolopaciceps is found to be a valid taxon, but placement within Pterodactylus is inappropriate. Consequently, the new genus Aerodactylus is erected to accommodate it. Aerodactylus can be diagnosed on account of a unique suite of characters including jaws containing 16 teeth per-jaw, per-side, which are more sparsely distributed caudally and terminate rostral to the nasoantorbital fenestra; dorsal surface of the skull is subtly depressed rostral of the cranial table; rostrum very elongate (RI = ∼7), terminating in a point; orbits correspondingly low and elongate; elongate cervical vertebrae (approximately three times the length of their width); wing-metacarpal elongate, but still shorter than the ulna and first wing-phalanx; and pteroid approximately 65% of the total length of the ulna, straight and extremely thin (less than one third the width of the ulna). A cladistic analysis demonstrates that Aerodactylus is distinct from Pterodactylus, but close to Cycnorhamphus Seeley, 1870, Ardeadactylus Bennett, 2013a and Aurorazhdarcho Frey, Meyer and Tischlinger, 2011, consequently we erect the inclusive taxon Aurorazhdarchidae for their reception.  相似文献   

16.
The Upper Elliot Formation of South Africa and Lesotho contains the world's most diverse fauna of early Jurassic ornithischian dinosaurs. Nevertheless, despite four decades of work on this fauna there remains significant taxonomic confusion and many important specimens remain undescribed. A review of the non-heterodontosaurid ('fabrosaurid') ornithischians of the Upper Elliot Formation is presented, following re-examination of all known ornithischian material from the Elliot Formation. ' Fabrosaurus australis' is based upon a single undiagnostic dentary, and is here considered a nomen dubium . Lesothosaurus diagnosticus is considered to be valid and is rediagnosed based upon a unique combination of plesiomorphic and derived characteristics. Stormbergia dangershoeki gen. et. sp. nov. is described from three partial skeletons including numerous postcranial material. Stormbergia dangershoeki is significantly larger than previously described Elliot Formation ornithischians, and can be recognized on the basis of a unique combination of characters, the most important of which is the possession of a distinctive tab-shaped obturator process on the ischium. A preliminary systematic analysis is presented, the results of which differ significantly from other recent ornithischian phylogenies.  © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society , 2005, 145 , 175–218.  相似文献   

17.
The Middle–Upper Oxfordian foraminifera were studied from the borehole section drilled in the east of the Moscow Region (Russia). The foraminiferal zones were distinguished in Oxfordian clays: Opthalmidium strumosum–Lenticulina brestica and Lenticulina russiensis–Epistomina uhligi. It was established that the distribution of foraminiferal assemblages varies throughout the Moscow Region.  相似文献   

18.
Palaeoberesellids, tubular septate dasycladacean algae hitherto only described from the Upper Palaeozoic, have been discovered in the Late Jurassic Arab-D Reservoir from the Khurais Oilfield, Saudi Arabia. Material is referred to a new species, Kamaena khuraisensis . Specimens occur in the wackestones and packstones of the lower part of the reservoir, deposited in offshore shelf environments deeper than those containing most of the other described Arab Reservoir dasycladaceans.  相似文献   

19.
Graciela Delvene 《Geobios》2003,36(5):519-531
The four sections richest in bivalves from the Middle and Upper Jurassic of the Iberian Range (Spain) were selected for a quantitative palaeoecological analysis of the bivalve fraction of the macrobenthos. Five bivalve associations and two assemblages were recognized with the help of a Q-mode hierarchical cluster analysis (Ward method). The main environmental factors controlling bivalve associations are thought to be substrate, water energy and distribution of organic matter. The bivalves exhibit a distinct spatial and temporal distribution pattern within the Aragonian Branch of the Iberian Range. Four of the bivalve associations occur in the Upper Oxfordian (Sot de Chera Fm) and one association in the Lower Callovian (Chelva Fm). In the Sot de Chera and Loriguilla formations, the abundance of bivalves decreases from NW to SE i.e., from relatively close to the shore line towards the distal-most part of the carbonate platform. In the Chelva Fm, bivalves are abundant in the Ariño region, interpreted as a palaeogeographic high. The spatial distribution of bivalves might have been largely controlled by the availability of nutrients.  相似文献   

20.
Two new genera and five new species of Archegocimicidae are described from the Upper Jurassic of the Shar-Teg locality in Mongolia: Shartegocimex rasnitsyni, gen. et sp. nov., S. distans, sp. nov., Shartegocorpus paranotalis, gen. et sp. nov., Saldonia formosa, sp. nov., S. insolita, sp. nov.  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