A forefin of Leptonectes solei from the Lower Jurassic (Pliensbachian) of Dorset,UK

An incomplete forefin in the collections of the National Museum of Wales, Cardiff, is herein assigned to the rare leptonectid species, Leptonectes solei, known only from the west Dorset coast. It is only the third specimen of the species and is smaller than both the holotype and referred specimen. The new specimen is from the Lower Jurassic (lower Pliensbachian, Charmouth Mudstone Formation, Tragophylloceras ibex Ammonite Zone, Acanthopleuroceras valdani Ammonite Subzone) of Seatown, Dorset, UK. It confirms that all three species of Leptonectes were present in the Pliensbachian and expands the known diversity of ichthyosaurs for that time period. We show that isolated forefins of Leptonectes can be assigned to a species with a high degree of confidence.     

New coelacanth material from the Middle Triassic of eastern Switzerland, and comments on the taxic diversity of actinistans

New coelacanth material from the Middle Triassic Prosanto Formation of the Ducan and Landwasser area near Davos in eastern Switzerland, Canton Graubünden, is described. A sub-complete individual is visible in ventral view, and shows details of its branchial apparatus. In particular, it possesses relatively large teeth on the ceratobranchials, and possible ossified hypobranchials. Few diagnostic characters are observable, and most of them are visible on the mandibles preserved in lateral view. This specimen shares characters with Ticinepomis peyeri, a smaller form from the Middle Triassic of Monte San Giorgio, whose holotype is re-described in part here. A second specimen, a fragmentary caudal skeleton shows the typical supplementary lobe of coelacanths, and meristic characters indicating probable close affinities with T. peyeri. We refer this material to Ticinepomis cf. T. peyeri. Because the new specimen is larger than the holotype, we refute the possible juvenile status of the small specimen from Monte San Giorgio. The new material of Ticinepomis from Canton Graubünden shows anatomical features not preserved on the holotype and allows the addition of new characters to a previously published data matrix of actinistians. A phylogenetic analysis is performed, which supports that Ticinepomis is nested among the Latimeriidae. The diversity of post-Palaeozoic coelacanths is assessed. The taxic diversity of observed occurrences shows a peak in the Early Triassic and a peak in the Late Jurassic, as detected in previous studies. When ghost lineages are included in the computation, the Late Jurassic peak is smoothened. By comparing the taxic diversity curves with the curve of average ghost lineage duration, we conclude that the Early Triassic peak of diversity was probably caused by a biological radiation, whereas the Late Jurassic peak of observed diversity is probably the result of a Lagerstätten effect.     

A reassessment of Iteravis huchzermeyeri and Gansus zheni from the Jehol Biota in western Liaoning,China

The authors reassessed the taxonomic distinction of Iteravis huchzermeyeri and Gansus zheni, which are two species of Ornithuromorpha based on specimens from the same locality in western Liaoning and derive from the Jehol Biota. The detailed comparisons of the holotype and referred specimens of both species, reveal no anatomical features that distinguish these taxa as separate species. Some minor differences are considered to relate to ontogenetic or interspecific differences. The stratigraphic occurrence for both specimens is the Lower Cretaceous Jiufotang Formation. Accordingly, the authors conclude that Iteravis huchzermeyeri has priority, by 15 days, for this taxon and that Gansus zheni is a junior synonym. The diagnosis of Iteravis huchzermeyeri is revised based on further study on all specimens referred to this species. Its generic distinction from Gansus is maintained thereby removing a potential genus-level correlation linking Xiagou Formation in Gansu Province with the Jiufotang Formation in Liaoning Province.     

Late Albian ammonites from the Aitamir Formation (Koppeh Dagh,northeast Iran)

Late Albian ammonite faunas from the Aitamir Formation of the Koppeh Dagh Basin in northeast Iran are described and illustrated. These comprise 14 taxa, several of which are recorded from Iran for the first time, namely Anahoplites planus (formerly recorded from central Iran in open nomenclature only), Semenoviceras solidus, Epihoplites (Metaclavites) iphitus, Hysteroceras orbignyi and Pseudhelicoceras robertianum. New records of Placenticeras grossouvrei extend the stratigraphic range of this species downwards into the Late Albian; previously it was known from the Early and Middle Cenomanian only. The record of the rare E. (M.) iphitus fills a palaeobiogeographic gap between Crimea and Tajikistan, and the holotype of Spath is re-illustrated here. Additionally, Epihoplites trapezoidalis, from the Late Albian of Tajikistan, is relegated into the synonymy of Spath's species. A large number of taxa typical of the Late Albian (upper part of the Gault Clay Formation) of northwest Europe indicate close palaeobiogeographic affinities with the Koppeh Dagh Basin and faunal exchange across the Russian Platform and Transcaspia. The stratigraphic succession of the ammonite faunas is used for a biostratigraphic subdivision of the upper Aitamir Formation.     

Morphological restudy of the type species of Xibeiestheria (Spinicaudata) from the lower Aptian,northwestern China

The fossil clam shrimp genus Xibeiestheria Wang in Shen et al., 1982, a component of the well-known Early Cretaceous Yanjiestheria fauna, was originally described from the lower Aptian Jingchuan Formation of Yanchi County, Ningxia Hui Autonomous Region of northwestern China. The morphological re-examination under an SEM of the holotype of the type species Xibeiestheria pora Wang in Shen et al., 1982 has revealed new taxonomic features not previously recognized. These include: (1) growth lines with serrated lower margins, having a row of small pores; (2) widely spaced radial lirae intercalated cross bars on growth bands in the dorsal part of the carapace; (3) fine reticulum occurring within coarse reticulation on growth bands in the middle part of the carapace; (4) puncta radially aligned along the widely spaced radial lirae on growth bands in the lower part of the carapace.     

Biostratigraphic and biogeographic implications of a hadrosaurid (Ornithopoda: Dinosauria) from the Upper Cretaceous Almond Formation of Wyoming,USA

The results of Barnum Brown's 1937 expedition to the Almond Formation of Wyoming consisted of two unidentified ceratopsian skulls and a partial hadrosaurid specimen (AMNH 3651). The hadrosaurid is here attributed to the Maastrichtian genus Saurolophus, verifying previous biostratigraphic correlations of this formation using ammonite zones. Fossiliferous lower Maastrichtian formations occurring latitudinally between those of Alberta, Canada, and southwestern Texas, USA, such as the Almond Formation, are essential for testing the effects and duration of apparent hadrosaurid faunal segregation earlier in the Campanian, and indirectly aiding in the placement of faunal boundaries that are currently unknown for the late Campanian. The discovery of Saurolophus in Wyoming, a close relative of the Campanian genus Prosaurolophus, affirms that the segregation of hadrosaurid faunas established in the late Campanian (～75 Ma) continued for at least 3 million years. Combining occurrences of Saurolophus from Mongolia and the Moreno Formation of California with those of Alberta, Canada, this genus appears to have had one of the largest geographic ranges of any equivalent clade of hadrosaurid dinosaur, although species level distributions are still uncertain.     

Edentulous pterosaurs from the Cambridge Greensand (Cretaceous) of eastern England with a review of Ornithostoma Seeley, 1871

A re-examination of fossil material from the Late Cretaceous Cambridge Greensand Member (CGM) of the West Melbury Marly Chalk Formation revealed a number of new specimens of edentulous pterosaur jaw fragments previously identified as shark fin spines and fish jaws and accessioned under the epithet ‘cestraciontid finray’ and ‘jaws of fish’. These are now recognised as pterosaurian jaw tips and referred to Ornithostoma sedgwicki Seeley, 1891 and Azhdarchoidea indet. This material increases the diversity of edentulous pterosaurs from the CGM.The edentulous pterosaur Ornithostoma sedgwicki Seeley, 1891 from the Cretaceous Cambridge Greensand of eastern England is reviewed. The holotype specimen is confirmed as a fragment of a premaxilla/maxilla of a non-tapejarid azhdarchoid on account of the conspicuous curvature of the dorsal and occlusal margins posteriorly and the presence of small neural foramina on the lateral margins. Neural foramina are not seen on jaws of members of the Pteranodontia, a group to which O. sedgwicki was included previously. The referral of O. sedgwicki to Azhdarchoidea eliminates the single known Lower Cretaceous occurrence of Pteranodontidae, restricting the temporal range of this taxon to the Upper Cretaceous. Postcranial material referred to O. sedgwicki from the type horizon is regarded as indeterminate Pterosauria.     

Redescription of Tuarangisaurus keyesi (Sauropterygia; Elasmosauridae), a key species from the uppermost Cretaceous of the Weddellian Province: Internal skull anatomy and phylogenetic position

The systematics of elasmosaurids are not well resolved partially because of the scarcity of well-preserved skull material. Among Weddellian elasmosaurids, one exception to this is the holotype of Tuarangisaurus keyesi from upper Campanian–lower Maastrichtian levels of the Maungataniwha Sandstone Member of the Tahora Formation, Mangahouanga Stream, inland Hawke's Bay, New Zealand. The material preserves an almost complete cranium and mandible. This material is re-described here, based on new observations and digital reconstruction of the internal anatomy. The result adds one new autapomorphy to the diagnosis of the taxon: ectopterygoid with large boss on the ventral surface and a posteriorly directed process. Additionally new features are recorded: presence of stapes; pterygoid overlapping the vomer, medial sulcus on the dorsal surface of the vomer, parasphenoid–basisphenoid complex covering the ventral surface of the body of the basioccipital. The presence of stapes in Tuarangisaurus keyesi is surprising as they were previously considered absent among elasmosaurids. Phylogenetic analysis indicates a clear elasmosaurid affinity, although there is low resolution within the Elasmosauridae. The previously proposed close relationship with the early Aptian Callawayasaurus colombiensis is rejected.     

Palaeomagnetic,geochronological and geological constraints on the tectonic evolution of the Mejillones Peninsula,northern Chile

Palaeomagnetic and geochronological data from an Early Palaeozoic high grade metamorphic complex (Jorgina Formation) and Jurassic layered basic intrusion (Moreno Complex) are reported from the Mejillones Peninsula of northern Chile (23–23°30'S). ⁴⁰Ar–³⁹Ar dates from the Lower Palaeozoic Jorgina Formation and the Moreno Complex are between 170 and 158 Ma, coincident with a phase of emplacement of the north Chilean coastal batholith. This suggests that intrusion and magnetization of the Moreno Complex and the metamorphism and remagnetization of the Jorgina Formation were related to batholith emplacement. Extracted stable components of magnetization from all units (17 sites) define site-mean directions with a scattered distribution. The scatter in site-mean directions is interpreted as being due to minor, localized, non-uniform, block-fault related (normal or strike-slip, or both) rotation after 158 Ma. The palaeomagnetic and geochronological data indicate that no significant large-scale latitudinal translation of crustal blocks has taken place in this part of northern Chile since the Late Jurassic. In addition, they indicate that the uniform clockwise rotation after the mid-Cretaceous which affected the adjacent Cordillera de la Costa either did not extend into the Mejillones Peninsula or took the form of localized block-fault rotations. The restriction of palaeomagnetically defined styles of rotation to discrete areas within the north Chilean forearc indicates that forearc wide block-fault rotation models are not applicable to the Pacific margin of northern Chile.     

A New Juvenile Specimen of Lufengosaurus Huenei Young, 1941 (Dinosauria: Prosauropoda) from the Lower Jurassic Lower Lufeng Formation of Yunnan, Southwest China

Abstract: A skull and a series of associated cervical vertebrae (ZLJ0112) discovered from the Lower Lufeng Formation (Lower Jurassic) are determined as a juvenile specimen of Lufengosaurus huenei Young 1941 based on amended autapomorphies. Differences between ZLJ0112 and the holotype (sub-adult specimen) are considered as ontogenetic characteristic changes of L. huenei. Since some of these differences are present in other prosauropod dinosaurs (i.e., forms of the maxillary vascular foramen are irregular; the frontal contribution to the dorsal margin of the orbit is substantial; the frontal contribution to the supratemporal fossa is absent; the supratemporal fenestra is visible in lateral view; the supraoccipital inclined at 75 degrees; the parasphenoid rostrum lies level with the occipital condyle; the retroarticular process is short; the axial postzygapophysis project caudally beyond the end of the centrum) they may be common ontogenetic changes in prosauropod dinosaurs.     

The taxonomic identity of a nearly complete ankylosaurid dinosaur skeleton from the Gobi Desert of Mongolia

Mongolian Paleontological Center (MPC) 100/1305 is one of the most complete ankylosaurid skeletons ever collected, and includes much of the postcranial skeleton and numerous in situ osteoderms. This specimen has been referred to Saichania chulsanensis, based on the similarity of the skull compared to the holotype of Saichania, MPC 100/151. However, MPC 100/1305 does not include a skull, and so referral of MPC 100/1305 to Saichania must be based on postcranial characters. Comparison of the postcrania of MPC 100/1305 and MPC 100/151 reveals several differences in the scapula, humerus, and metacarpals, indicating that MPC 100/1305 should not be referred to Saichania. Additionally, although it was previously reported that MPC 100/1305 was collected from the Baruungoyot Formation at Khulsan in Mongolia, collection records indicate that this specimen was instead collected from the Djadokhta Formation at Zamyn Khond. Two ankylosaurid species are known from the Djadokhta Formation of Mongolia and China, Pinacosaurus grangeri and P. mephistocephalus. There are no diagnostic characters in MPC 100/1305 that can be used to refer this specimen to P. grangeri or P. mephistocephalus, and there are a few differences between MPC 100/1305 and Pinacosaurus, such as the number of caudal vertebrae, and morphology of the coracoid, which have uncertain taxonomic implications. At present, MPC 100/1305 is best referred to Ankylosauridae indet., or cf. Pinacosaurus, based on its generally congruent morphology with Pinacosaurus and its provenance from the Djadokhta Formation, in which Pinacosaurus is the only recognized ankylosaurid taxon.     

Kazaklambia convincens comb. nov., a primitive juvenile lambeosaurine from the Santonian of Kazakhstan

The holotype of ‘Procheneosaurus’ convincens, a juvenile lambeosaurine, is the most complete hadrosaurid known from Kazakhstan. North American species of Procheneosaurus are considered juveniles of Corythosaurus, Hypacrosaurus, and Lambeosaurus, rendering the generic name unusable. A replacement name, Kazaklambia convincens comb. nov., is herein proposed as this specimen is morphologically distinct from other Eurasian taxa and known juvenile lambeosaurines at a similar ontogenetic stage in having a prefrontal process of the postorbital with a dorsal thickening forming a dome lateral to the frontal dome, doming of the nasal anterodorsal to the orbit, and a frontal length/width ratio <1. The juvenile status of Kazaklambia makes phylogenetic placement difficult; however, morphometric and morphological information (particularly in relation to the hollow cranial crest and the length of the frontal) suggest a close affiliation with the basal lambeosaurines Amurosaurus and Tsintaosaurus, and support the hypothesis for an Asian origin for Lambeosaurinae.     

A new specimen of Ichthyosaurus communis from Dorset,UK, and its bearing on the stratigraphical range of the species

This paper describes a new ichthyosaur specimen from the Stonebarrow Marls Member (Charmouth Mudstone Formation) of Charmouth, Dorset. It is substantially complete and various characters of the skull (snout ratios and basioccipital morphology) and appendicular skeleton (the number of digits on the hind paddle, which can be used to infer the number of digits on the front paddle) indicate that the specimen is referable to Ichthyosaurus communis. This provides the first direct evidence for the presence of I. communis in the Pliensbachian, extending the stratigraphic range of the species. The specimen also preserves a probable gullet content, which demonstrates that fish formed part of the diet of this individual.     

Anurans from the Candeleros Formation (?Cenomanian-Turonian) of west-central Argentina: new evidence for pipoid evolution

The fluvio-lacustrine deposits of the ?Cenomanian-Turonian Candeleros Formation in the northwestern fringe of Patagonia have yielded numerous remains of vertebrates, including anurans. A new, partially articulated immature specimen of a small pipimorph pipoid from the upper part of this unit is described herein. Although incompletely preserved, the morphology and proportions of the skeleton are strongly reminiscent of corresponding elements of the holotype of Avitabatrachus uliana from the lower section of the same formation at a nearby locality, thus suggesting that these specimens might represent the same, or a closely related, taxon. The new specimen is a metamorphosing individual: it has a zygapophyseal articulation between the sacrum and the neural arch of a postsacral vertebra that bears conspicuous transverse processes, and four pairs of ribs. These traits are not present in the available material of A. uliana, but they might have occurred within the normal range of variation of a single species. Although the generic and specific allocation of the new material is uncertain, a parsimony analysis performed to clarify the relationships of A. uliana supports a phylogenetic placement of this taxon outside the crown Pipidae. The evidence provided by the Candeleros anurans confirms the presence of stem pipids in Patagonia in the early Late Cretaceous.     

A New Titanosaurian Sauropod from Late Cretaceous of Nei Mongol, China

A specimen collected from the Upper Cretaceous Erlian Formation of Nei Mongol （Inner Mongolia）, China, represents a new genus and species of titanosaurian sauropod. The new taxon is named and described on the basis of the holotype and the only known specimen, which comprises several dorsal, sacral, and caudal vertebrae, several dorsal ribs, one anterior chevron, and much of the pelvis. Diagnostic features of the new species include a thick ridge extending down from the postzygapophysis on the lateral surface of the neural arch of the posterior dorsal vertebrae, a transversely oriented accessory lamina present between the anterior centroparapophyseal limina and the lateral centraprezygapophyseal lamina of the posterior dorsal vertebrae, long, anteroventrally directed caudal rib that bears two distinctive fossae on its posterior margin on the anterior caudal vertebrae and a prominent vertical ridge above the pubic peduncle on the medial surface of the ilium, among others. The ilium is pneumatic, a feature not common among non-avian dinosaurs. The new taxon has an unusual combination of primitive and derived character states. Preliminary character analysis shows a complex character distribution within the Titanosauriformes. Recent titanosauriform discoveries suggest that a significant radiation occurred in Asia early in the titanosauriform evolution.     

A new species of Tupuxuara (Thalassodromidae,Azhdarchoidea) from the Lower Cretaceous Santana Formation of Brazil,with a note on the nomenclature of Thalassodromidae

A new species of the sail-crested pterosaur Tupuxuara is described from the Santana Formation of Brazil, Tupuxuara deliradamus sp. nov. The holotype, a partial skull, and a larger, partial skull referred to the same taxon differs from Tupuxuara leonardii by having a nasoantorbital fenestra with an acutely-angled posterior border with a long, straight posterodorsal margin, a reclined cranium, and an orbit situated entirely in the ventral half of the nasoantorbitral fenestra. Unfortunately, neither specimen is comparable with the fragmentary rostrum representing Tupuxuara longicristatus. In addition, resolution of a recent nomenclatural problem over the correct name for the clade containing Tupuxuara and its sister taxon, Thalassodromeus, is provided. Both genera are used by different authors as the nomenclatural basis for the group, but “Tupuxuaridae” has never been explicitly erected as a new taxon, and therefore fails to meet ICZN criteria that new taxa are only valid if authors clearly indicate their intention to establish new names. By contrast, “Thalassodrominae” was explicitly erected as a name for the Thalassodromeus + Tupuxuara clade, thereby fulfilling all ICZN requirements for naming of a new taxon and making Thalassodromeus stand as the type genus for this group.     

A new species of Pluridens (Mosasauridae: Halisaurinae) from the upper Campanian of Southern Nigeria

The Upper Cretaceous of Africa has produced a diverse fauna of mosasaurs, including the highly specialized, long-jawed Pluridens. The type of Pluridens walkeri comes from the Maastrichtian Farin-Doutchi Formation of Niger, with a second, referred specimen coming from the Campanian section of the Campanian-Maastrichtian Nkporo Shale near Calabar, in southern Nigeria. Comparisons of this referred specimen with the holotype suggest that it represents a distinct and more primitive species. The Calabar jaw resembles P. walkeri in being long and narrow anteriorly with a shallow subdental shelf, and in having small, numerous, recurved teeth with medially positioned replacement pits. However, it lacks many of the derived features that characterize Pluridens walkeri, such as the extremely long and straight jaw, the extreme lateral protrusion and subcircular section of the dentary, strong transverse expansion of the dental thecae, and extreme reduction and increase in number of the teeth. The Calabar Pluridens is therefore referred to a new species, Pluridens calabaria. Following recent studies, Pluridens is considered to represent a highly derived member of the Halisaurinae. The marked differences between the Campanian and Maastrichtian species of the genus underscore the rapid pace of mosasaur evolution during the Cretaceous.     

An ichthyosaur (Reptilia: Ichthyosauria) specimen from the Lower Cretaceous (Berriasian) Spilsby Sandstone Formation of Nettleton,Lincolnshire, UK

A fragmentary ichthyosaur specimen collected in situ at Castle Top Quarry in Nettleton, Lincolnshire, UK from exposures of the Lower Cretaceous (Berriasian) Spilsby Sandstone Formation (Subcraspedites ?preplicomphalus Zone) is reported. In general, Early Cretaceous ichthyosaurs from the Berriasian to Barremian are poorly understood. Despite the fragmentary nature of the described specimen, it is the first ichthyosaur reported from this specific zone and adds to the literature another rare ichthyosaur from the Berriasian.     

Organic maturity of Late Cretaceous and Tertiary coal measures,Canadian Arctic Archipelago

Maastrichtian and Lower Tertiary strata of the Eureka Sound Formation are widespread in the Canadian Arctic Archipelago and include major resources of lignite, subbituminous and high-volatile bituminous coal. The level of organic maturity of the strata for the most part reflects pre-orogenic (pre-Late Eocene-Miocene) depths of burial and thus helps define Early Tertiary depositional patterns. In the Remus Basin, in the eastern Canadian Archipelago, over 90 seams of coal occur ranging in rank from lignite (0.15% R_{0 max}) to high-volatile bituminous (0.70% R_{0 max}). The maturity values at the base of the Eureka Sound Formation, in conjunction with measured maturation gradients, indicate a maximum paleothickness of 4500 m and outline a basin with well defined eastern, western and southern margins. On the bases of numerical modeling, the maturation gradients are interpreted to reflect paleogeothermal gradients up to 55°C/km in the eastern part of the basin and of about 20°C/km in the western part.Elsewhere in the Canadian Arctic Archipelago the level of organic maturity of the Eureka Sound Formation varies from 0.15% R_{0 max} to 0.70% R_{0 max}. Maturation gradients measured from Meighen Island in the Strand Fiord Basin and from Melville Island in the southern part of the West Sverdrup Basin are about 0.10 log R_{0 max/km}, and when compared to numerical models suggest paleogeothermal gradients on the order of 15°C/km. At Meighen Island the paleodepth of burial of the Eureka Sound Formation may have been up to 6000 m. As a first approximation, the Melville Island gradient is considered representative of West Sverdrup and Banks Basin. Using this gradients, a paleodepth of burial of 3000 m is calculated for central West Sverdrup Basin and 4000 m for the southern part. In Banks Basin the paleodepth of burial is estimated to be on the order of 4000 m. Maturity values obtained from the Lake Hazen and Judge Dally Basins, Eclipse Trough and Somerset, Devon and Cornwallis Islands and at Bache Peninsula on eastern Ellesmere Island cannot be readily interpreted in terms of paleodepth of burial. No measured sections are thick or complete enough to establish maturation gradients, and the Tertiary history of these areas is only poorly known.The low paleogeothernal gradients calculated from Meighen Island, Melville Island and from the western part of the Remus Basin (15–20°C/km) are considered to reflect low heat flow or rapid Tertiary sedimentation and uplift such that an equilibrium geothermal gradient may never have existed. The higher maturation gradients and interpreted paleogeothermal gradients in the eastern Remus Basin are considered to be the product of higher heat flow on eastern Ellesmere Island.Anomalously high levels of maturity obtained along the Stolz Fault and adjacent Strand Fiord on Axel Heiberg Island are attributed to the thermal effects of evaporite diapirs.