New dwarf crocodylomorph from the Upper Jurassic of Portugal and the first neuroanatomical data for Atoposauridae

Results of work near Moab, Utah, by U. S. Geological Survey field parties in 1926 in part accord with and in part differ from current interpretations. In the Salt Valley anticline lower Mississippian rocks occur as limestone boulders in a conglomerate of unknown age. The oldest rocks in place at the surface are Pennsylvanian (Hermosa formation), sharply separated from the Permian by contained marine faunas. The Permian formations (Rico and Cutler) are not sharply separated. The former contains marine limestones; the latter, tongues of white sandstone that increase southwestward and at top the sandstone member (De Chelly?) locally known as the White Rim. The Lower Triassic Moenkopi formation, including in Green River Valley a marine limestone member, rests with unconformit upon Cutler and is in turn overlain unconformably by Upper(?) Triassic Shinarump conglomerate. Shinarump grades upward into the Chinle formation and is not recognizable as a separate unit at many localities, especially toward the east. A group of Jurassic(?) formations, including Wingate and Navajo sandstones separated by the Todilto(?) formation, rests unconformably upon the Chinle. The formations of the group are conformable and have arbitrary common boundaries. The succeeding Carmel and Entrada formations (Upper Jurassic) are similar to this group. The Carmel formation may overlie the Navajo sandstone with unconformity. Summerville formation (Upper Jurassic) intertongues with the underlying Entrada sandstone so that Entrada lithology extends higher toward the east. Summerville is sep rated by an unconformity from the overlying Salt Wash sandstone member of the Morrison formation (Cretaceous?). Dakota(?) sandstone (Upper Cretaceous) rests unconformably upon the Morrison formation and is succeeded by the Mancos shale. The stratigraphy would seem to indicate the following events in the history of the region: Possibly folding and erosion between lower Mississippian and Pennsylvanian; folding and erosion at the close of the Permian; erosion and possibly folding between Lower and Upper Triassic, and between Upper Triassic and Jurassic(?) (Wingate); possibly erosion preceding Upper Jurassic (Carmel); erosion between Upper Jurassic and Cretaceous(?) (Morrison), and between Cretaceous(?) and Upper Cretaceous. End_Page 785------------------------------

Gondwanaland origin, dispersion, and accretion of East and Southeast Asian continental terranes

The allochthonous Hawasina complex is a sedimentary sequence of both continental-slope and oceanic-basin deposits that were thrust up over shallow-water marine carbonates of the Arabian Shelf during the Late Cretaceous. The Hawasina tectonically overlies the autochthonous Hajar Super Group, and is overlain tectonically by the Samail Ophiolite and associated sedimentary rocks. The lower thrust units, the Hamat Duru Group, and Wahrah Al Ayn Formations, are generally interpreted as limestone and sandstone turbidites deposited on the continental rise. The Wahrah Formation and lower Zulla and upper Sid'r Formations within the Hamrat Duru Group all contain thick sequences of radiolarian-bearing chert. Samples collected from the Zulla and Wahrah (lower chert member) Formations yielded radiolarian faunas assignable to the Late Triassic (Karnian/Norian) based on key species of the genera Capnodoce, Capnuchosphaera, Eptingium, Sarla, Triassocampe, and Yeharaia. Additional samples from the Zulla Formation indicate an Early Jurassic (Pliensbachian) age based on the presence of Broctus, Canoptum, Canutus, Droltus, and Pseudoheliodiscus sp.; previous investigators sugge ted a hiatus in pelagic sedimentation during Early Jurassic time. Radiolarian faunas extracted from two measured sections of the Wahrah Formation (upper chert member) range in age from the Late Jurassic (Tithonian) to Early Cretaceous (late Valanginian/Hauterivian). No suitable radiolarian faunas were obtained from cherts of the Sid'r Formation (Hamrat Duru Group). The higher thrust units are represented by the conglomeratic Al Ayn Formation, and the deeper water Halfa and Haliw Formations. Radiolarian faunas extracted from a measured section near the type locality of the Halfa Formation range in age from the Late Jurassic (Kimmeridgian/Tithonian) to the Early Cretaceous (Hauterivian/Barremian). All the radiolarian faunas obtained thus far from the Haliw Formation are assignable to the Late Triassic (late Karnian to middle Norian) based on fragments of Capnodoce and Veghicyclia sp. Previous biostratigraphic data suggested that the thickest sections of radiolarian chert and mudstone were deposited during Late Jurassic and Early Cretaceous time. Newly obtained paleontologic evidence based on radiolarian biostratigraphy indicates that significant pelagic sedimentation occurred also during the Late Triassic and Early Jurassic. End_of_Article - Last_Page 425------------

Brachiosauridae is a clade of titanosauriform sauropod dinosaurs that includes the well-known Late Jurassic taxa Brachiosaurus and Giraffatitan. However, there is disagreement over the brachiosaurid affinities of most other taxa, and little consensus regarding the clade’s composition or inter-relationships. An unnamed partial sauropod skeleton was collected from middle–late Oxfordian (early Late Jurassic) deposits in Damparis, in the Jura department of eastern France, in 1934. Since its brief description in 1943, this specimen has been informally known in the literature as the ‘Damparis sauropod’ and ‘French Bothriospondylus’, and has been considered a brachiosaurid by most authors. If correctly identified, this would make the specimen the earliest known titanosauriform. Coupled with its relatively complete nature and the rarity of Oxfordian sauropod remains in general, this is an important specimen for understanding the early evolution of Titanosauriformes. Full preparation and description of this specimen, known from teeth, vertebrae and most of the appendicular skeleton of a single individual, recognises it as a distinct taxon: Vouivria damparisensis gen. et sp. nov. Phylogenetic analysis of a data matrix comprising 77 taxa (including all putative brachiosaurids) scored for 416 characters recovers a fairly well resolved Brachiosauridae. Vouivria is a basal brachiosaurid, confirming its status as the stratigraphically oldest known titanosauriform. Brachiosauridae consists of a paraphyletic array of Late Jurassic forms, with Europasaurus, Vouivria and Brachiosaurus recovered as successively more nested genera that lie outside of a clade comprising (Giraffatitan + Sonorasaurus) + (Lusotitan + (Cedarosaurus + Venenosaurus)). Abydosaurus forms an unresolved polytomy with the latter five taxa. The Early Cretaceous South American sauropod Padillasaurus was previously regarded as a brachiosaurid, but is here placed within Somphospondyli. A recent study contended that a number of characters used in a previous iteration of this data matrix are ‘biologically related’, and thus should be excluded from phylogenetic analysis. We demonstrate that almost all of these characters show variation between taxa, and implementation of sensitivity analyses, in which these characters are excluded, has no effect on tree topology or resolution. We argue that where there is morphological variation, this should be captured, rather than ignored. Unambiguous brachiosaurid remains are known only from the USA, western Europe and Africa, and the clade spanned the Late Jurassic through to the late Albian/early Cenomanian, with the last known occurrences all from the USA. Regardless of whether their absence from the Cretaceous of Europe, as well as other regions entirely, reflects regional extinctions and genuine absences, or sampling artefacts, brachiosaurids appear to have become globally extinct by the earliest Late Cretaceous.

Chapter 5 Stratigraphic evidence for northwest to southeast tectonic transport of jurassic terranes in central Mexico and the caribbean (western Cuba)

Rudists arose in the Late Jurassic and survived for nearly 100 m.y. before becoming extinct at the end of the Cretaceous. Over this interval they diversified gradually during the Late Jurassic and Early Cretaceous, rapidly in the mid-Cretaceous, then more slowly in the Late Cretaceous. Total rates of origination and extinction during the Late Jurassic and Early Cretaceous were uniform and comparable to those reported for other groups. The Late Cretaceous, however, was characterized by high and widely fluctuating total origination and extinction rates. Per taxon rates reveal a similar pattern except for high and variable rates in the Jurassic. The number of genera increased from the Oxfordian to a peak in the Cenomanian, decreased in the Turonian and Coniacian coinciding with a minor mass extinction event, and rose to a zenith in the Maastrichtian. Unlike other groups investigated, the rudists were at their highest level of diversity immediately prior to their disappearance.Rudist genera survived for a mean of 12 m.y., whereas families survived for a mean of 48 m.y. Survivorship curves for generic cohorts, based upon survival of all rudist genera that evolved during each stage, exhibit a concave shape when the effects of mass extinction and variance at low diversities are considered. Causal factors involved in the final disappearance of the rudists remain unclear; however, their tropical provinciality in the Late Cretaceous contributed to their vulnerability to mass extinction.

The Wallowa terrane is one of five pre-Cenozoic terranes in the Blue Mountains province of Oregon, Idaho, and Washington. The other four terranes are Baker, Grindstone, Olds Ferry, and Izee. The Wallowa terrane includes plutonic, volcanic, and sedimentary rocks that are as old as Middle Permian and as young as late Early Cretaceous. They evolved during six distinct time segments or phases: (1) a Middle Permian to Early Triassic(?) island-arc phase; (2) a second island-arc phase of Middle and Late Triassic age; (3) a Late Triassic and Early Jurassic phase of carbonate platform growth, subsidence, and siliciclastic sediment deposition; (4) an Early Jurassic subaerial volcanic and sedimentary phase; (5) a Late Jurassic sedimentary phase that formed a thin subaerial and thick marine overlap sequence; and (6) a Late Jurassic and Early Cretaceous phase of plutonism. Rocks in the Wallowa terrane are separated into formally named units. The Permian and Triassic Seven Devils Group encompasses the Middle and Late(?) Permian Windy Ridge and Hunsaker Creek Formations and the Middle and Late Triassic Wild Sheep Creek and Doyle Creek Formations. Some Permian and Triassic plutonic rocks, which crystallized beneath the partly contemporaneous volcanic and sedimentary rocks of the Seven Devils Group, represent magma chambers that fed the volcanic rocks. The Permian and Triassic plutonic rocks form the Cougar Creek and Oxbow “basement complexes,” the Triassic Imnaha plutons, and the more isolated Permian and Triassic plutons, such as those in the Sheep Creek to Marks Creek chain and in the southern Seven Devils Mountains near Cuprum, Idaho. The Seven Devils Group, and its associated plutons, are capped by the Martin Bridge Formation, a Late Triassic platform and reef carbonate unit, with associated shelf and upper-slope facies, and overlying and partly contemporaneous siliciclastic, limestone, and calcareous phyllitic rocks of the Late Triassic and Early Jurassic Hurwal Formation. Younger rocks are a subaerial Early Jurassic volcanic and sedimentary rock unit of the informally named Hammer Creek assemblage, and a Late Jurassic overlap sedimentary unit, the Coon Hollow Formation. Late Jurassic and Early Cretaceous plutons intrude the older rocks. Lava flows of the Miocene Columbia River Basalt Group overlie the pre-Cenozoic rocks. Late Pleistocene and Holocene sedimentation left discontinuous deposits throughout the canyon. Most impressive are deposits left by the Bonneville flood. The latest interpretations for the origin of terranes in the Blue Mountains province show that the Wallowa terrane is the only terrane that, during its Permian and Triassic evolution, had an intra-oceanic (not close to a continental landmass) island-arc origin. On this field trip, we travel through the northern segment of the Wallowa terrane in Hells Canyon of the Snake River, where representative rocks and structures of the Wallowa terrane are well exposed. Thick sections of lava flows of the Columbia River Basalt Group cap the older rocks, and reach river levels in two places.

Pleurosternon bullockii is a turtle from the Early Cretaceous of Europe known from numerous postcranial remains. Only one skull has so far been referred to the species. Pleurosternon bullockii belongs to a group of turtles called pleurosternids, which is thought to include several poorly known taxa from the Late Jurassic and Early Cretaceous of Europe and North America. Pleurosternids and baenids, a group of North American turtles that lived from the Late Cretaceous to the Eocene, define a clade called Paracryptodira. Additionally, Paracryptodira likely includes compsemydids, and, potentially, helochelydrids. Character support for Paracryptodira is relatively weak, and many global phylogenetic studies fail to support paracryptodiran monophyly altogether. Proposed paracryptodiran synapomorphies are largely cranial, despite the poor characterization of pleurosternid cranial material. In addition to their questionable monophyly, the global position of paracryptodires is debated. Early studies suggest crown-turtle affinities, but most phylogenies find them as stem-turtles, irrespective of their monophyly. Here, we document the cranial osteology of Pleurosternon bullockii with the use of three-dimensional models derived from segmenting high-resolution X-ray micro-computed tomography (CT) scans. Pleurosternon bullockii has a primitive basipterygoid region of the skull, but a cryptodire-like acustico-jugular region. A surprising number of similarities with pleurodires exist, particularly in the laterally expanded external process of the pterygoid and in the posterior orbital wall. Our observations constitute an important step toward a phylogenetic re-evaluation of Paracryptodira.

Continental humid and arid zones during the jurassic and cretaceous

Dryolestes leiriensis is a Late Jurassic fossil mammal of the dryolestoid superfamily in the cladotherian clade that includes the extant marsupials and placentals. We used high resolution micro-computed tomography (µCT) scanning and digital reconstruction of the virtual endocast of the inner ear to show that its cochlear canal is coiled through 270°, and has a cribriform plate with the spiral cochlear nerve foramina between the internal acoustic meatus and the cochlear bony labyrinth. The cochlear canal has the primary bony lamina for the basilar membrane with a partially formed (or partially preserved) canal for the cochlear spiral ganglion. These structures, in their fully developed condition, form the modiolus (the bony spiral structure) of the fully coiled cochlea in extant marsupial and placental mammals. The CT data show that the secondary bony lamina is present, although less developed than in another dryolestoid Henkelotherium and in the prototribosphenidan Vincelestes. The presence of the primary bony lamina with spiral ganglion canal suggests a dense and finely distributed cochlear nerve innervation of the hair cells for improved resolution of sound frequencies. The primary, and very probably also the secondary, bony laminae are correlated with a more rigid support for the basilar membrane and a narrower width of this membrane, both of which are key soft-tissue characteristics for more sensitive hearing for higher frequency sound. All these cochlear features originated prior to the full coiling of the therian mammal cochlea beyond one full turn, suggesting that the adaptation to hearing a wider range of sound frequencies, especially higher frequencies with refined resolution, has an ancient evolutionary origin no later than the Late Jurassic in therian evolution. The petrosal of Dryolestes has added several features that are not preserved in the petrosal of Henkelotherium. The petrosal characters of dryolestoid mammals are essentially the same as those of Vincelestes, helping to corroborate the synapomorphies of the cladotherian clade in neural, vascular, and other petrosal characteristics. The petrosal characteristics of Dryolestes and Henkelotherium together represent the ancestral morphotype of the cladotherian clade (Dryolestoidea + Vincelestes + extant Theria) from which the extant therian mammals evolved their ear region characteristics. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166, 433–463.

Geochronological, structural, and sedimentological data provide the basis for a regional synthesis of the evolution of the Cordilleran retroarc thrust belt and foreland basin system in the western U.S.A. In this region, the Cordilleran orogenic belt became tectonically consolidated during Late Jurassic time (∼155 Ma) with the closure of marginal oceanic basins and accretion of fringing arcs along the western edge of the North American plate. Over the ensuing 100 Myr, contractile deformation propagated approximately 1000 kilometers eastward, culminating in the formation of the Laramide Rocky Mountain ranges. At the peak of its development, the retroarc side of the Cordillera was divided into five tectonomorphic zones, including from west to east the Luning-Fencemaker thrust belt; the central Nevada (or Eureka) thrust belt; a high-elevation plateau (the “Nevadaplano”); the topographically rugged Sevier fold-thrust belt; and the Laramide zone of intraforeland basement uplifts and basins. Mid-crustal rocks beneath the Nevadaplano experienced high-grade metamorphism and shortening during Late Jurassic and mid- to Late Cretaceous time, and the locus of major, upper crustal thrust faulting migrated sporadically eastward. By Late Cretaceous time, the middle crust beneath the Nevadaplano was experiencing decompression and cooling, perhaps in response to large-magnitude ductile extension and isostatic exhumation, concurrent with ongoing thrusting in the frontal Sevier belt. The tectonic history of the Sevier belt was remarkably consistent along strike of the orogenic belt, with emplacement of regional-scale Proterozoic and Paleozoic megathrust sheets during Early Cretaceous time and multiple, more closely spaced, Paleozoic and Mesozoic thrust sheets during Late Cretaceous–Paleocene time. Coeval with emplacement of the frontal thrust sheets, large structural culminations in Archean-Proterozoic crystalline basement developed along the basement step formed by Neoproterozoic rifting. A complex foreland basin system evolved in concert with the orogenic wedge. During its early and late history (∼155 - 110 Ma and ∼70 - 55 Ma) the basin was dominated by nonmarine deposition, whereas marine waters inundated the basin during its midlife (∼110 - 70 Ma). Late Jurassic basin development was controlled by both flexural and dynamic subsidence. From Early Cretaceous through early Late Cretaceous time the basin was dominated by flexural subsidence. From Late Cretaceous to mid-Cenozoic time the basin was increasingly partitioned by basement-involved Laramide structures. Linkages between Late Jurassic and Late Cretaceous Cordilleran arc-magmatism and westward underthrusting of North American continental lithosphere beneath the arc are not plainly demonstrable from the geological record in the Cordilleran thrust belt. A significant lag-time (∼20 Myr) between shortening and coeval underthrusting, on the one hand, and generation of arc melts, on the other, is required for any linkage to exist. However, inferred Late Jurassic lithospheric delamination may have provided a necessary precondition to allow relatively rapid Early Cretaceous continental underthrusting, which in turn could have catalyzed the Late Cretaceous arc flare-up.

Mesophytic floras (Late Triassic-Early Cretaceous) of the Arctic are irregularly distributed and poorly studied. The floras studied in more detail are Carnian-Norian of Spitsbergen, Rhaetian and early Lias of East Greenland, Late Jurassic of the Lena basin, and Early Cretaceous of West Greenland, Spitsbergen, Franz Josef Land, and the Lena and Kolyma basins. Mesozoic floras of Arctic Islands were not isolated from continental ones. Undoubtedly close connection existed between the Late Triassic floras of Spitsbergen and Franz Josef Land and the middle Keuper floras of Western Europe; the Early Cretaceous floras of Spitsbergen, Kong Karls Land, Franz Josef Land, and Kotel'nyy Island were connected with coeval floras of northern Asia. Botanic-geographic zonation was more prominent during the second phase (Late Jurassic-Early Cretaceous) of the mesophytic floras than during the first phase (Late Triassic-Middle Jurassic). It is assumed that Late Triassic floras of Spitsbergen and Franz Josef Land comprised a special part of the European province of the Indo-European paleofloristic area. Late Triassic thermophilic vegetation traces are preserved in the southern Lena basin (Aldan River). Beginning in the Early Jurassic temperate vegetation formed in the Lena basin (Vilyuy trough) and farther south (South Yakutsk basin and other regions); later, in the Middle Jurassic temperate vegetation appeared farther north (lower Yenisey River), and then more widely in the Late Jurassic, and especially in the Early Cretaceous Arctic and Subarctic floras. The Early Jurassic flora of northeastern USSR (west bank of the Kolyma River) is similar to the Indo-European area floras; it is possible that an Indo-European and Siberian area boundary is farther north than Central Siberia, or that a special area existed which included Early Jurassic floras of southern Alaska. Late Jurassic and Early Cretaceous Arctic floras (except West Greenland floras) are typical floras of the Siberian paleofloristic area. The Arctic climate changed between Late Triassic and Early Cretaceous times from a hot (possibly tropical) climate to a temperate warm and humid climate favorable for profuse woody plant development. End_of_Article - Last_Page 2511------------

A new ichnospecies of a large theropod dinosaur, Megalosauripus transjuranicus, is described from the Reuchenette Formation (Early–Late Kimmeridgian, Late Jurassic) of NW Switzerland. It is based on very well-preserved and morphologically-distinct tracks (impressions) and several trackways, including different preservational types from different tracksites and horizons. All trackways were excavated along federal Highway A16 near Courtedoux (Canton Jura) and systematically documented in the field including orthophotos and laserscans. The best-preserved tracks were recovered and additional tracks were casted. Megalosauripus transjuranicus is characterized by tridactyl tracks with clear claw and digital pad impressions, and notably an exceptionally large and round first phalangeal pad on the fourth digit (PIV1) that is connected to digit IV and forms the round heel area. Due to this combination of features, M. transjuranicus clearly is of theropod (and not ornithopod) origin. M. transjuranicus is compared to other Megalosauripus tracks and similar ichnotaxa and other unassigned tracks from the Early Jurassic to Early Cretaceous. It is clearly different from other ichnogenera assigned to large theropods such as Eubrontes–Grallator from the Late Triassic and Early Jurassic or Megalosauripus–Megalosauropus–Bueckeburgichnus and Therangospodus tracks from the Late Jurassic and Early Cretaceous. A second tridactyl morphotype (called Morphotype II) is different from Megalosauripus transjuranicus in being subsymmetric, longer than wide (sometimes almost as wide as long), with blunt toe impressions and no evidence for discrete phalangeal pad and claw marks. Some Morphotype II tracks are found in trackways that are assigned to M. transjuranicus, to M.? transjuranicus or M. cf. transjuranicus indicating that some Morphotype II tracks are intra-trackway preservational variants of a morphological continuum of Megalosauripus transjuranicus. On the other hand, several up to 40 steps long trackways very consistently present Morphotype II features (notably blunt digits) and do not exhibit any of the features that are typical for Megalosauripus (notably phalangeal pads). Therefore, it is not very likely that these tracks are preservational variants of Megalosauripus transjuranicus or Megalosauripus isp. These trackways are interpreted to have been left by an ornithopod dinosaur. The high frequency of large theropod tracks in tidal-flat deposits of the Jura carbonate platform, associated on single ichnoassemblages with minute to medium-sized tridactyl and tiny to large sauropod tracks has important implications for the dinosaur community and for paleoenvironmental and paleogeographical reconstructions. As with most other known occurrences of Megalosauripus tracks, M. transjuranicus is found in coastal settings, which may reflect the preference of their theropod trackmakers for expanded carbonate flats where food was abundant.

Goniodromitidae is an extinct family of primarily Jurassic and Cretaceous crabs that are found mainly in Europe. Herein, we report upon a diversity hotspot for goniodromitids from the Koskobilo quarry in northern Spain exposing mid-Cretaceous (Albian/Cenomanian) coral reef limestones. Five species of goniodromitid are described and discussed: Distefania incerta, D. renefraaijei n. sp., Eodromites grandis, Goniodromites laevis, and Navarradromites pedroartali n. gen., n. sp. Furthermore, Distefania centrosa is herein synonymized with D. incerta. Eodromites grandis was previously known only from the Late Jurassic, resulting in a time gap of 45 Myr. Other species of decapod with long time ranges are known. Additionally, the Spanish representatives of Eodromites grandis are the only Cretaceous specimens known from this genus. Species of the genera Distefania, Eodromites, and Goniodromites were predominantly found in coral/sponge limestones from the Jurassic and Cretaceous of Europe and were important for the survival of the family into the Cretaceous and indirectly into the Paleocene.

The Queyras ophiolite West of Monte Viso (Western Alps): Indicator of a pecular ocean floor in the mesozoic tethys