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 15 毫秒
1.
Cacibupteryx caribensis gen. et sp. nov. is a new pterosaur of the family Rhamphorhynchidae found in western Cuba, in rocks of the Jagua Formation (Middle–Upper Oxfordian). The holotype, a skull and part of the left wing, is one of the few Jurassic pterosaurs that is well preserved in three dimensions. The new taxon shares characters with early and late Jurassic pterosaurs, and is one of the few late Jurassic taxa from western Laurasia and Gondwana. Furthermore, Cacibupteryx joins Nesodactylus hesperius Colbert from Cuba, and Sordes pilosus Sharov, from Kazakhstan as the most complete pterosaur recorded from the Middle–Upper Oxfordian. Cacibupteryx caribensis is one of the largest Jurassic pterosaurs known, and its skull possesses several distinct characters, including relatively broad roof elements (mainly frontal and parietal bones), a jugal with a prominent recess, occipital table trapezoidal in shape with the maximum width between the quadrate bones, and a small fenestra located in the posterior part of the pterygoid bones. In the Oxfordian, the Caribbean Corridor separated Laurasia and western Gondwana. The diversity of the marine herpetofauna found in the Jagua Vieja Member (Jagua Formation), and of teleostean fish, confirms that the corridor was an effective seaway over which flew at least Nesodactylus and Cacibupteryx .  相似文献   

2.
A new species of an atoposaurid crocodilian, Theriosuchus guimarotae, is described from the Late Jurassic (Kimmeridgian) of Portugal. Theriosuchus guimarotae can be distinguished from other species of Theriosuchus by a lateral surface of squamosal bevelled ventrally; a rounded, caudally projecting and dorsally sculptured caudolateral corner of the squamosal; a premaxillomaxillary suture aligned caudomedially in dorsal aspect; a minimum space between the supratemporal foramina that comprises one third of the total width of the cranial table; a minimum width of the frontal between the orbits that comprises one third of the maximum width of the skull at the orbits; a dentition that comprises only pseudocaniniform and lanceolate-shaped teeth; the presence of an external mandibular fenestra and all vertebral bodies amphicoelous. Its osteology also sheds light on the diagnosis of Theriosuchus within Atoposauridae. The material additionally includes specimens representative of several ontogenetic stages, each of which is discussed here. With its Late Jurassic age, T. guimarotae represents the oldest well-preserved material of Theriosuchus and reveals further knowledge about the palaeobiogeography of the genus in western Europe.  相似文献   

3.
JAN REES 《Palaeontology》2010,53(4):887-902
Abstract: Callovian and Oxfordian strata in Ogrodzieniec near Zawiercie, southern Poland, have yielded two shark tooth assemblages that collectively include 14 neoselachian taxa. A previously unrecognised member of the Orectolobiformes, Akaimia altucuspis gen. et sp. nov., is described and characterised by a dentition remarkably similar to modern wobbegong sharks (Orectolobidae) by convergence. The assemblages also include the first anterior teeth ever found of the palaeospinacid ‘Synechodusprorogatus Kriwet, in addition to teeth from two other palaeospinacids, Sphenodus spp., four different orectolobiforms, two hexanchids and Protospinax spp. These shark tooth assemblages contribute to the poorly known Callovian and Oxfordian neoselachian faunas and indicate that the diversity was higher than previously appreciated, particularly within the Orectolobiformes.  相似文献   

4.
The Kachchh Oxfordian ammonoid stratigraphic record for over 150 years remained restricted largely to Early Oxfordian condensed oolitic facies in the relatively distal Mainland Kachchh. Recently, it has been enlarged with the discovery in 1994 of over 200 m-thick uncondensed Middle to Late Oxfordian succession at Kantkote in the proximal part of the basin. Apart from abundant Perisphinctinae and Mayaitinae, a 10 m-thick sediment interval in the lower half of the above succession yielded a few examples of Gregoryceras. The specimens are here identified as G. gr. devauxi Bert and Enay and in view of their association with Larcheria subschilli (Lee) are assigned to the Middle Oxfordian Subschilli Horizon of the Schilli Subzone. Gregoryceras distribution south of the equator in Kachchh, Chile, Mexico and Madagascar, all within 35-40° latitude marks the southern limit of its latitudinal expansion during the first order maximum flooding surface (MFS) of the Schilli Subzone of the Kachchh Toarcian-Hauterivian Sequence. The maximum ammonoid diversity, density and frequency of the Kachchh first order sequence coupled with dominance of mayaitins and perisphinctins suggest over 20 m depth in the Gregoryceras interval. Distinctly greater bathymetry in the 200 km distally away basinal part causes sediment starved situation, and explains the Middle Oxfordian to early Early Kimmeridgian submarine nondepositional hiatus in the Mainland Kachchh.  相似文献   

5.
Five cyrtocrinid crinoid taxa previously unknown from the epicratonic deposits of Poland, as well as associated millericrinids and isocrinids, are described. The studied materials were derived mainly from the Lower and Middle Oxfordian, but crinoids are also from uppermost Callovian and/or lowermost Oxfordian sediments of the Polish Jura Chain (southern Poland). The crinoids, preserved as more or less complete (e.g., basal circlets) cups, include Lonchocrinus dumortieri, Phyllocrinus belbekensis, Remisovicrinus polonicus, Remisovicrinus aff. polonicus, Tetracrinus moniliformis and Sclerocrinus sp. The occurrence of Remisovicrinus polonicus in the late Middle Oxfordian of the southern Poland is confirmed. Moreover, the present study extends the geographic range of all cyrtocrinid species studied and discusses their unusual environmental adaptations.  相似文献   

6.
Two new species of fossil snipe flies (Rhagionidae) from the Daohugou Formation of Chifeng City in Inner Mongolia Autonomous Region (northeastern China) are described as Palaeoarthroteles jurassicus nov. sp. and P. pallidius nov. sp. They are the first record of the genus Palaeoarthroteles Kovalev and Mostovski beyond Siberia, which have implications for stratigraphic correlation of the formations in which they are found.  相似文献   

7.
Decapod crustaceans are the most conspicuous predators and scavengers of modern chemosynthesis-based ecosystems at hydrothermal vents and hydrocarbon seeps; however, very little is known about decapod crustaceans at ancient seeps or vents. Some decapods, including galatheids, are known to produce highly specific, internally structured microcoprolites. Late Jurassic (Oxfordian) hydrocarbon-seep limestones from Beauvoisin (southeastern France) were found to contain such microcoprolites including Favreina fontana n. isp., F. cf. martellensis Brönnimann and Zaninetti, Palaxius salataensis Brönnimann, Cross and Zaninetti and Palaxius isp. These diverse ichnofossils indicate that crustaceans were also a part of ancient chemosynthesis-based ecosystems. This is the first report of crustacean coprolites from a deep-water environment.  相似文献   

8.
Two new fossil species, Archaeohelorus polyneurus sp. n. and A. tensus sp. n., assigned to the genus Archaeohelorus Shih, Feng & Ren, 2011 of Heloridae (Hymenoptera), are reported from the late Middle Jurassic, Jiulongshan Formation of Inner Mongolia, China. Based on the well-preserved forewings and hind wings of these specimens, the diagnosis of the Archaeohelorus is emended: forewing 2cu-a intersecting Cu and Rs+M at the same point or postfurcal, and hind wing may have tubular veins C, Sc+R, R, Rs, M+Cu, M and Cu distinct, or simplified venation. The new findings also elucidate the evolutionary trend of forewing and hind wing venation and body size for the Heloridae from the late Middle Jurassic to now.  相似文献   

9.
10.
A new genus, Anabariceras, and two new species, A. meledinae and A. aspectabile, are described from the Upper Callovian-Lower Oxfordian boundary beds from the Anabar River basin. Based on analysis of the ontogenetic development of major characters (suture, shell shape, and ornamentation), the affinity of this genus to the subfamily Quenstedtoceratinae is substantiated.  相似文献   

11.
Leptocereus santamarinae is newly described as endemic to the dry evergreen forests of the keys and mainland coast of northeastern Cuba. Its closest relationship appears to be withL. sylvestris, of the southeastern coastal woods of Cuba. A key to the twelve known species ofLeptocereus is provided.  相似文献   

12.
Appendicular elements of the sauropod dinosaur Suuwasseaemilieae, from the Upper Jurassic Morrison Formation of Montana, USA, display a peculiar mix of autapomorphic and plesiomorphic features. While more similar in overall morphology to Apatosaurus than other flagellicaudatans, the coracoid of Suuwassea lacks the quadrangular shape of Apatosaurus. The humerus of Suuwassea bears a pronounced proximal tuberculum, a feature seen elsewhere only in saltasaurine titanosaurian sauropods. The rectangular proximal articular surface of the tibia is proportioned neither like Diplodocus nor Apatosaurus type specimens, although this region may be intraspecifically variable. The pes of Suuwassea possesses plesiomorphically elongate phalanges and a small, uncompressed ungual, unlike other flagellicaudatans except Dyslocosaurus. The localization of tooth marks on the pedal elements suggests that sauropod feet may have been singled out by scavengers, as has been noted for elephants.  相似文献   

13.
A new specimen of the widespread Middle Jurassic to Lower Cretaceous Asian gonipholidid crocodilian genus Sunosuchus is described on the basis of a partial skeleton from the Upper Toutunhe Formation (Middle Jurassic, ?Bathonian-Callovian) of Liuhonggou, SW of Urumqi, Xinjiang Uygur Autonomous Region, People’s Republic of China. The specimen is represented by a partial mandible, teeth, vertebrae, limb and girdle bones and osteoderms. It can be distinguished from other nominal species of the genus by a unique combination of characters: slightly heterodontous dentition, strongly sculptured posteroventral part of the mandible, short fenestra mandibularis, convex dorsal surface of the retroarticular process, keeled cervical vertebral centra and ventral osteoderms with a distinctive sculpture of wide pits and narrow ridges. The heterodontous dentition is a potential autapomorphy of this form. The new specimen is closest in morphology to material described recently from the Callovian of Kirghisia as Sunosuchus sp. It represents the second Middle Jurassic record of the genus, the first crocodile from the Toutunhe Formation, the first substantial crocodile find from the Mesozoic of the Southern Junggar Basin, and the first Middle Jurassic record of Sunosuchus from China. This extends both the paleobiogeographical distribution of the genus in Asia and its stratigraphic distribution in China considerably.  相似文献   

14.
An abundant ichnological material composed of xiphosuran trackways and isolated traces was discovered in Upper Jurassic limestones from the Causses Basin (Causse Méjean, Lozère, France). The morphology of the imprints supports their identification as Kouphichnium isp. In contrast to the most frequent case, the trackways are composed of omnipresent pusher imprints sometime associated with leg traces, but with no telson mark. We argue that this pattern reflects actual surface traces rather than an incomplete set of undertracks. The size distribution of the sampled ichnites is broadly bimodal. This is best explained by sexual dimorphism, a phenomenon frequently observed in modern xiphosurans. Analysis of the trace fossils further suggests that several growth stages are recorded and that the horseshoe crabs were walking in a protected and flat environment like a lagoon. This area, certainly close to a mating ground, was occasionally affected by a continental influence. The biometric study of the tracks suggests a gigantic size for the trackmakers whose body may have reached 84 cm in length. This discovery complements the few reports on other gigantic horseshoe crabs in the Jurassic of Western Europe, thus casting doubt on the postulated increase in body size from the Palaeozoic to the Recent. Furthermore, a literature review shows that there are still major gaps in the record of limulid body-fossils and tracks. Thus, neither of these archives can be taken at face value for quantifying the body-size evolution of horseshoe crabs.  相似文献   

15.
Abstract: The Jurassic was an important period in the evolution of Testudinata and encompasses the origin of many clades, and this is especially true of Jurassic turtles from Western Europe. A new genus and species of Late Jurassic turtle, Hispaniachelys prebetica gen. et sp. nov. from the upper Oxfordian of the Prebetic (Southern Spain), is described on the basis of postcranial material. The specimen is the only known tetrapod from the Mesozoic of the Prebetic and the oldest turtle from southern Europe. A mosaic of characters indicates this is a new genus: it displays basal features including dorsal epiplastral processes/reduced cleithra, no medial contact of the extragulars and a long first thoracic rib, alongside derived characters including an absence of mesoplastra and the vertebral 3/4 sulcus crossing neural 5. The phylogenetic position of the new taxon is hard to resolve, and it might be either a paracryptodire or a basal testudine, but it is distinct from Plesiochelys. A complex taphonomic history is shown by a range of overlying grazing traces and bioerosion on the carapace. The carapace was subsequently overturned and buried ventrally up, terminating grazing activity, and was then bored by sponges before final burial. Scanning electron microscopy reveals phosphatic microspheroids associated with bacterial decay in the vascular cavities of the cancellous bone, suggesting the carapace may have acted as a closed microenvironment in which decay‐derived authigenic minerals formed.  相似文献   

16.
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   

17.
The youngest fossil Golunda (Rodentia, Muridae) is described from the Late Pleistocene fluvio-lacustrine deposits, exposed at Dulam (Bageshwar), Kumaun Lesser Himalaya, India. The age of fossiliferrous horizon is estimated as 31,000 yr BP. A new species, Golunda dulamensis nov. sp. has highly derived characters, e.g., antero-posteriorly stretched molars, upper molars with more length and less width, stephanodonty, cusps in M3 strongly inclined backward giving the molars a very stretched aspect, and metaconid and entoconid in M3 forming almost straight lingual row of the cusps. Gdulamensis nov. sp. is most similar to present day Gellioti but differs from the later slightly by larger size, a thin connection between t4 and t5 in M1, and comparatively larger entoconid and very weakly developed antero-labial cusp in M3. We suggest that highly specialized molars of Gdulamensis nov. sp. and present day Gellioti are derivable through Gkelleri. We also propose that Golunda migrated from Asia to Africa, not from Africa to Asia as was thought by earlier workers.  相似文献   

18.
Carsten Helm  Immo Schülke 《Facies》2006,52(3):441-467
Small reefal bioconstructions that developed in lagoonal settings are widespread in a few horizons of the Late Jurassic (Oxfordian) succession of the Korallenoolith Formation, exposed southwest of Hannover, Northwest Germany. Especially the florigemma-Bank Member, “sandwiched” between oolite shoal deposits, exposes a high variety of build-ups, ranging from coral thrombolite patch reefs, to biostromes and to coral meadows. The reefs show a distribution with gradual facies variations along an outcrop belt that extends about 30 km from the Wesergebirge in the NW to the Osterwald Mts in the SE.The patch reefs from the Deister Mts locality at the “Speckhals” are developed as coral-chaetetid-solenoporid-microbialite reefs and represent a reef type that was hitherto unknown so far north of its Tethyan counterparts. They are mainly built up by coral thickets that are preserved in situ up to 1.5 m in height and a few metres in diameter. They contain up to 20 coral species of different morphotypes but are chiefly composed of phaceloid Stylosmilia corallina and Goniocora socialis subordinately. The tightly branched Stylosmilia colonies are stabilized by their anastomosing growth. The coral branches are coated with microbial crusts and micro-encrusters reinforcing the coral framework. Encrusters and other biota within the thicket show a typical community replacement sequence: Lithocodium aggregatum, Koskinobullina socialis and Iberopora bodeuri are pioneer organisms, whereas the occurrence of non-rigid sponges represents the terminal growth stage. The latter are preserved in situ and seem to be characteristic so far poorly known constituents of the Late Jurassic cryptobiont reef dweller community. The distance and overall arrangement of branches seems to be the crucial factor for the manifestation of a (cryptic) habitat promoting such community replacement sequences. Widely spaced branches often lack any encrusting and/or other reef dwelling organisms, whereas tightly branched corals, as is St. corallina, stimulate such biota. Hence, such reefs are well suited for research on coelobites and community sequences of encrusting and cavity dwelling organisms.  相似文献   

19.
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   

20.
Four phylogenetically independent lineages of frogs are currently known to sequester lipid-soluble skin alkaloids for which a dietary source has been demonstrated. We report here a remarkable fifth such instance, in Eleutherodactylus iberia and Eleutherodactylus orientalis, two species of miniaturized frogs of the family Eleutherodactylidae from Cuba. Six pumiliotoxins and two indolizidines were found in E. iberia, one of the smallest frogs in the world and characterized by a contrasting colour pattern for which we hypothesize an aposematic function. Analyses of stomach content indicated a numerical prevalence of mites with an important proportion of oribatids-a group of arthropods known to contain one of the pumiliotoxins detected in E. iberia. This suggests that miniaturization and specialization to small prey may have favoured the acquisition of dietary skin alkaloids in these amphibians.  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