Steneosaurus edwardsi (Thalattosuchia: Teleosauridae), the largest known crocodylomorph of the Middle Jurassic

Teleosaurids were a clade of marine crocodylomorphs that were globally distributed during the Jurassic Period. They evolved a wide range of body sizes, from small (～2–3 m) to very large (> 9 m). Until now, the largest known Middle Jurassic teleosaurid was ‘Steneosaurus’ obtusidens, from the Oxford Clay Formation of the UK. Here, we re‐examine a very large Oxford Clay specimen (ilium, ischium, and femur) that had been tentatively attributed to ‘S.’ obtusidens. Based on comparative anatomical study with the ‘S.’ obtusidens holotype and referred specimens of Steneosaurus edwardsi and Steneosaurus leedsi, we conclude that this very large individual actually pertains to S. edwardsi. Based on comparisons with the Machimosaurus mosae neotype (which has a complete femur and skeleton), we estimate a total length in excess of 7 m for this large S. edwardsi individual, making it the largest known Middle Jurassic teleosaurid. Therefore, along with the closely related genus Machimosaurus, this clade of large‐bodied Middle–Late Jurassic teleosaurids were the largest species during the first 100 million years of crocodylomorph evolution. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, ●● , ●●–●●.     

A revision of the sauropod dinosaur genus ‘Bothriospondylus’ with a redescription of the type material of the Middle Jurassic form ‘B. madagascariensis’

Abstract: The sauropod dinosaur ‘Bothriospondylus’, originally named on the basis of Late Jurassic remains from England, is demonstrated to be invalid, and the characters used to diagnose it are shown to be obsolescent features which are widespread throughout Sauropoda. Material referred to this genus spans a temporal range from the Middle Jurassic until the early Late Cretaceous and has been described from five different countries, across three continents. These remains represent a wide array of sauropod groups, comprising non‐neosauropod eusauropods, a macronarian, titanosauriforms (including at least one definite brachiosaurid) and a rebbachisaurid. The type material of the Middle Jurassic ‘B. madagascariensis’ represents a derived non‐neosauropod eusauropod and possesses two potential autapomorphies. However, as a result of the fragmentary nature of the material and the uncertainty surrounding its association, a new taxon is not erected. Of the numerous specimens referred to ‘Bothriospondylus’, however, several remains are considered diagnostic: Ornithopsis hulkei (Early Cretaceous, UK), Lapparentosaurus madagascariensis (Middle Jurassic, Madagascar) and Nopcsaspondylus alarconensis (early Late Cretaceous, Argentina). At least three types of sauropod were present in the Bathonian (Middle Jurassic) of north‐west Madagascar, with a basal eusauropod (Archaeodontosaurus), a more derived eusauropod (‘B. madagascariensis’) and a titanosauriform (Lapparentosaurus) all approximately contemporaneous. Palaeocontinental reconstructions suggest that Middle Jurassic Madagascan sauropods would still have been capable of global biotic interchange, and this is perhaps reflected in their diverse assemblage. Re‐evaluation of these Malagasy forms has shed new light on this important time period in sauropod evolution.     

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.     

Sunosuchus (Archosauria, Crocodyliformes) from the Toutunhe Formation (Middle Jurassic) of the Southern Junggar Basin (Xinjiang, NW-China)

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.     

A new metriorhynchid crocodylomorph from the Lower Kimmeridge Clay Formation (Late Jurassic) of England,with implications for the evolution of dermatocranium ornamentation in Geosaurini

A new metriorhynchid crocodylomorph from the Lower Kimmeridge Clay Formation (Kimmeridgian, Upper Jurassic) of England is described. This specimen, a three‐dimensionally preserved skull and left mandibular ramus, is referred to a new species: T orvoneustes coryphaeus sp. nov. Within the genus Torvoneustes, T . coryphaeus sp. nov. is unique as it has a long anteromedial process of the frontal, ornamented dermatocranium, and the supraorbital notch forms a strongly acute angle. Our phylogenetic analysis confirms the placement of this specimen in Torvoneustes. The dentition of T . coryphaeus sp. nov. , like that of the type species, has a blunt apex, crown basal–mid regions with numerous tightly packed apicobasally aligned ridges, and apical region with an anastomosed pattern of ridges that interact with the carinae. Within Thalattosuchia these dental characteristics are only found in Torvoneustes and the teleosaurid Machimosaurus. The heavily ornamented dermatocranium of T . coryphaeus sp. nov. is in contrast to the unornamented (nasals and frontal)–lightly ornamented (maxillae and premaxillae) pattern seen in Torvoneustes carpenteri. Curiously, this pattern of reduction and loss of dermatocranium ornamentation is also observed in Metriorhynchus, Dakosaurus, and the subclade Rhacheosaurini. We hypothesize that the ‘smooth’ dermatocranium of Late Jurassic metriorhynchids evolved independently in each subclade (parallel evolution), and would have reduced drag, thereby making locomotion through water more energy efficient. © 2013 The Linnean Society of London     

The first find of chrysomelids (Insecta: Coleopetra: Chrysomeloidea) from Callovian-Oxfordian Daohugou biota of China

Tarsomegamerus mesozoicus nov. gen., nov. sp., an almost complete specimen of leaf beetle from the Callovian-Oxfordian of Daohugou Formation in Inner Mongolia, China is described. Tarsomegamerus mesozoicus is assigned to the Protoscelinae (Chrysomelidae, Coleoptera). This new leaf beetle represents the first record of chrysomeloids from Mesozoic of China and it extends the geographical distribution of Protoscelinae from central Asia into eastern Asia. This find provides new fossil material for studying the origin and evolution of Chrysomeloidea and by making a stratigraphic correlation of the correlative non-marine sedimentary rocks. Although the age of the Daohugou Formation is debatable it is most likely Callovian-Oxfordian (latest Middle Jurassic-earliest Late Jurassic) rather than early Middle Jurassic (late Aalenian-early Bajocian) or Early Cretaceous.     

Honghea xui gen. et sp. nov., the second Earliest Jurassic damsel-dragonfly (Odonata: Campterophlebiidae) from the Junggar Basin,NW China

A new campterophlebiid damsel-dragonfly, Honghea xui gen. et sp. nov., is described from the Lower Jurassic Badaowan Formation of the Junggar Basin, NW China. This is the second Chinese Campterophlebiidae recorded for the earliest Jurassic, reflecting the quick diversification and radiation of the damsel-dragonflies during this period. H. nouveau onghea gen. nov. is closely related to Chinese genera Zygokaratawia and Ctenogampsophlebia, both from the Middle Jurassic of the Daohugou Biota; but differs from these genera in having a larger wing size, RP2 slightly distal of Sn, and a narrower area between IR2 and RP3/4.     

A large pholidosaurid in the Phu Kradung Formation of north‐eastern Thailand

In the early 1980s, the remains of a large crocodilian, consisting of a nearly complete lower jaw, were referred to a distinct species of Sunosuchus, S. thailandicus. The specimen was recovered from a road‐cut near Nong Bua Lamphu, north‐eastern Thailand, in the upper part of the continental Phu Kradung Formation, and then considered Early to Middle Jurassic in age. Since then, this age has been revised and most of the formation is now considered Early Cretaceous, although a Late Jurassic age is possible for its lowermost part. Here, we report for the first time cranial elements associated with mandibular remains assignable to ‘S’. thailandicus. An attribution to Pholidosauridae is proposed on the basis of premaxillary morphology, and the original referral of this taxon to the goniopholidid Sunosuchus is discarded. A new genus name Chalawan now designates the originally described material of S. thailandicus. Nevertheless, the newly described specimen shares a characteristic with both ‘traditional’ Goniopholididae and Pholidosauridae: the presence of a depression located on the lateral wall of the maxilla and jugal. A phylogenetic analysis confirms the inclusion of both Goniopholididae and Pholidosauridae into a common clade, Coelognathosuchia tax. nov. Although the new Thai skull is much fragmented, its original shape is reconstructed and is compared with other pholidosaurid genera, namely Elosuchus, Meridiosaurus, Oceanosuchus, Pholidosaurus, Sarcosuchus and Terminonaris. The presence of the genus Sunosuchus being highly questionable in Thailand, it cannot be used as evidence to link the Chinese and Indochinese blocks. Instead, the recognition of a freshwater pholidosaurid in a continental formation of the Indochinese block suggests that early in their evolutionary history, these crocodilians, already known from Europe, Africa and South America, were more widely distributed along the northern margin of the Tethys than previously recognized.     

Revision of the disparid Stylocrinus (Crinoidea) from the Devonian of Europe,Asia and Australia

Abstract: The discovery of new specimens and the restudy of known collections result in revision of the diagnosis and the stratigraphic distribution of the disparid crinoid genus Stylocrinus, from the Middle and Upper Devonian of Europe, Asia and Australia. The consistent development of three basal plates, the atomous arms with internally inclined edges adjoining laterally with adjacent brachials in an interlocking network and an apparently rudimentary pinnulation is recognised. The high ecophenotypic plasticity of the common species S. tabulatus negates the validity of several former subspecies and demonstrates the general morphologic variability of the aboral cup proportions. This contrasts with the low morphological spectrum of rarer stylocrinid species. With exclusion of ‘S. elimatus’ (Silurian) from Stylocrinus, the genus is limited to the Devonian. A neotype is proposed for the lost holotype of S. tabulatus. Stylocrinus prescheri sp. nov. is described from the Eifelian to Givetian of Europe and Asia. The first evidence of the gastropod grazing trace fossil Radulichnus on a crinoid aboral cup (S. tabulatus), the post‐mortem incurred ossicular‐boring of radial and basal plates as well as the post‐mortem encrusting by a rugose coral are further observations on Stylocrinus aboral cups.     

Genetic analysis of the Linnaean Ulva lactuca (Ulvales,Chlorophyta) holotype and related type specimens reveals name misapplications,unexpected origins,and new synonymies

Current usage of the name Ulva lactuca, the generitype of Ulva, remains uncertain. Genetic analyses were performed on the U. lactuca Linnaean holotype, the U. fasciata epitype, the U. fenestrata holotype, the U. lobata lectotype, and the U. stipitata lectotype. The U. lactuca holotype is nearly identical in rbcL sequence to the epitype of U. fasciata, a warm temperate to tropical species, rather than the cold temperate species to which the name U. lactuca has generally been applied. We hypothesize that the holotype specimen of U. lactuca came from the Indo‐Pacific rather than northern Europe. Our analyses indicate that U. fasciata and U. lobata are heterotypic synonyms of U. lactuca. Ulva fenestrata is the earliest name for northern hemisphere, cold temperate Atlantic and Pacific species, with U. stipitata a junior synonym. DNA sequencing of type specimens provides an unequivocal method for applying names to Ulva species.     

Tettigarctidae (Insecta: Hemiptera: Cicadoidea) from the Middle Jurassic of Inner Mongolia, China

Three new species of Tettigarctidae from the Middle Jurassic of Daohugou, China are described: Shuraboprosbole daohugouensis nov. sp., S. minuta nov. sp., and S. media nov. sp. The revised diagnostic characters of Shuraboprosbole Becker-Migdisova are provided based on well-preserved whole-bodied fossil tettigarctids. So far, only four definitive species of Tettigarctidae are recorded from the Mesozoic of China. The pronotum concealing major of mesonotum seems to be an autapomorphy of Tettigarctinae. The “cicadellid-like tarsi” found in Cicadellidae and Brazilian Tettigarctidae are probably a parallel evolution.     

Redescription ofApristurus sibogae,and its taxonomic relationships (Lamniformes,Scyliorhinidae)

The holotype and only existing specimen ofApristurus sibogae was surveyed and was found to be very fragile, breaking down into several pieces, and strongly contracted. As the species is still only poorly known, the holotype was redescribed, reassessing the proportion of the contracted holotype. It was concluded thatA. sibogae is very similar to JapaneseA. platyrhynchus, but that it represents a distinct species, characterized by a short snout, posterior 1st and 2nd dorsal fins and a narrow interorbital region.     

A lower jaw of Palaeoxonodon from the Middle Jurassic of the Isle of Skye,Scotland, sheds new light on the diversity of British stem therians

The Middle Jurassic was a key interval of mammalian evolutionary history that witnessed the diversification of the therian stem group. Great Britain has yielded a significant record of mammalian fossils from this interval, represented by numerous isolated jaws and teeth from the Bathonian of Oxfordshire and the Isle of Skye. This record captures a key period in early cladotherian evolution, with amphitheriids, peramurans and ‘stem zatherians’ displaying intermediate talonid morphologies that document the evolutionary assembly of tribosphenic molars. We present a mandible with near‐complete dentition from the late Bathonian (c. 167.4–166.5 Ma) Kilmaluag Formation, near Elgol, Skye, representing the amphitheriid Palaeoxonodon ooliticus, previously known only from isolated teeth. The specimen sheds new light on the taxonomic diversity of British Middle Jurassic stem therians, as the morphological variation within the preserved tooth row encompasses that previously ascribed to three distinct species within two genera: Palaeoxonodon ooliticus, P. freemani and Kennetheridium leesi. Thus, both P. freemani and K. leesi are subjective junior synonyms of P. ooliticus. The dental formula of P. ooliticus (i4:c1:p5:m5) is intermediate between the primitively larger postcanine count (p5:m6–7) of Amphitherium and the reduced number in peramurans and tribosphenidans (p5:m3). Phylogenetic analyses of P. ooliticus generally confirm a close affinity with Amphitherium, but highlight the lack of strong empirical support for hypothesized patterns of divergences among early cladotherians.     

Cranial Anatomy and Palaeoneurology of the Archosaur Riojasuchus tenuisceps from the Los Colorados Formation,La Rioja,Argentina

Riojasuchus tenuisceps Bonaparte 1967 is currently known from four specimens, including two complete skulls, collected in the late 1960s from the upper levels of the Los Colorados Formation (Late Triassic), La Rioja, Argentina. Computed tomography (CT) scans of the skulls of the holotype and a referred specimen of Riojasuchus tenuisceps and the repreparation of the latter allows recognition of new features for a detailed analysis of its cranial anatomy and its comparison with a wide variety of other archosauriform taxa. The diagnosis of Riojasuchus tenuisceps is emended and two autapomorphies are identified on the skull: (1) a deep antorbital fossa with its anterior and ventral edges almost coinciding with the same edges of the maxilla itself and (2) a suborbital fenestra equal in size to the palatine-pterygoid fenestra. Also, the first digital 3D reconstruction of the encephalon of Riojasuchus tenuisceps was carried out to study its neuroanatomy, showing a shape and cranial nerve disposition consistent to that of other pseudosuchians.     

A New Basal Sauropod Dinosaur from the Middle Jurassic of Niger and the Early Evolution of Sauropoda

Background

The early evolution of sauropod dinosaurs is poorly understood because of a highly incomplete fossil record. New discoveries of Early and Middle Jurassic sauropods have a great potential to lead to a better understanding of early sauropod evolution and to reevaluate the patterns of sauropod diversification.

Principal Findings

A new sauropod from the Middle Jurassic of Niger, Spinophorosaurus nigerensis n. gen. et sp., is the most complete basal sauropod currently known. The taxon shares many anatomical characters with Middle Jurassic East Asian sauropods, while it is strongly dissimilar to Lower and Middle Jurassic South American and Indian forms. A possible explanation for this pattern is a separation of Laurasian and South Gondwanan Middle Jurassic sauropod faunas by geographic barriers. Integration of phylogenetic analyses and paleogeographic data reveals congruence between early sauropod evolution and hypotheses about Jurassic paleoclimate and phytogeography.

Conclusions

Spinophorosaurus demonstrates that many putatively derived characters of Middle Jurassic East Asian sauropods are plesiomorphic for eusauropods, while South Gondwanan eusauropods may represent a specialized line. The anatomy of Spinophorosaurus indicates that key innovations in Jurassic sauropod evolution might have taken place in North Africa, an area close to the equator with summer-wet climate at that time. Jurassic climatic zones and phytogeography possibly controlled early sauropod diversification.     

Elosuchus,a new genus of crocodile from the Cretaceous of the North of Africa

‘Thoracosaurus’ cherifiensis Lavocat, 1955, a longirostrine from the late Lower Cretaceous of Morocco and Algeria, is attributed to Elosuchus, n. g., with another species, E. felixi n. sp., from In Abangarit (Niger), of the same age. Stolokrosuchus from the Lower Cretaceous of Niger is also referred to the new family Elosuchidae. Synapomorphies and grades are indicated for the families of ‘mesosuchian’ longirostrine crocodiles, but no synapomorphy has been found to unite the families, except perhaps for the Thalattosuchia.     

Ginkgoalean woods from the Jurassic of Argentina: Taxonomic considerations and palaeogeographical distribution

A specimen of Baieroxylon rocablanquense nov. sp. from the Roca Blanca Formation (Early Jurassic), and a specimen of Ginkgomyeloxylon tanzanii Giraud and Hankel from the La Matilde Formation (Middle Jurassic), both located in the Santa Cruz province, Argentina, are described in detail. Identification of the morphogenus Baieroxylon is based upon secondary xylem characteristics (cross-field tracheid pitting, cross-fields and ray characters), while identification of Ginkgomyeloxylon is based upon pith, primary xylem and secondary xylem features. A synthesis of Ginkgoalean woods is presented, which combines diagnostic anatomical evidence with data related to stratigraphic and paleogeographical distributions. Based on the results of this analysis, a key for genus-level identification is provided and a new genus, Ginkgopitys, is proposed. These results are used to elucidate global patterns of historical distribution over the course of geological time. In Gondwana, a great diversity of “mixed-type” woods was present during the Mesozoic, especially during the Late Triassic. In contrast, in Laurasia a lower diversity of the mixed-type is recorded for the Paleozoic and Mesozoic, with increases in “abietinoid-type” wood – similar to extant Ginkgo – taking place at the beginning of the Cretaceous. During the Jurassic and Early Cretaceous in both Laurasia and Gondwana, mixed-type and abietinoid-type woods co-existed, illustrating that important evolutionary changes in wood anatomy occurred during the Mesozoic (Jurassic-Cretaceous).     

A stegosaur vertebra (Dinosauria: Ornithischia) from the Callovian (Middle Jurassic) of Sarthe, western France

A dinosaur vertebra found in the course of road works in the “Chevain Marls” (marine Callovian) of the Vermont outlier, near the village of Béthon (Sarthe, Pays-de-la-Loire, western France) is described and referred to a stegosaur (cf. Lexovisaurus). It is the first record of a dinosaur in the Middle Jurassic of that area. The specimen was probably derived from the floating carcass of an animal that had lived on the emerged areas of the Armorican Massif, near which the Chevain Marls were deposited. This fossil is an addition to the short list of stegosaur remains reported from France.     

Taxonomy,morphology and phylogeny of Late Cretaceous spirulid coleoids (Cephalopoda) from Greenland and Canada

Abstract: Groenlandibelus rosenkrantzi from the Maastrichtian of Greenland has long been thought to constitute an early representative of spirulid coleoids. This study shows that this view must be reassessed, at least in part. A re‐investigation of the types and of material recorded subsequently has revealed that none of these specimens is conspecific with the holotype of G. rosenkrantzi. Cyrtobelus birkelundae gen. nov, sp. nov. differs from the type of G. rosenkrantzi in having lower chambers and in lacking an apically elongated sheath. The longiconic phragmocone of G. rosenkrantzi has more features in common with the presumed spirulid genus Naefia. A specimen described in detail by J. A. Jeletzky in the mid 1960s as ‘G. rosenkrantzi’ is designated holotype of C. birkelundae sp. nov., which means that internal phragmocone features are still unknown in G. rosenkrantzi. Cyrtobelus hornbyense gen. nov, sp. nov. from the Campanian of western Canada constitutes the first record of early spirulids from the northeast Pacific, being based on seventeen extraordinarily well‐preserved phragmocones. This species differs from C. birkelundae sp. nov. only in the width of the siphuncular tube. The presence of a caecum, a nacre‐less conotheca that represents the continuation of the protoconch conotheca, conothecal flaps that anchor the mural parts of the septa, and a thin investment‐like sheath are characters shared only with Recent Spirula. In particular, the unusual protoconch architecture of Cyrtobelus gen. nov. challenges a phylogenetic origin within bactritoid‐like coleoids.