scholarly journals Hips, tips and sweet sweptback rays: Looking beyond traditional cranial characters in Pachycormiformes

2017 ◽  
Author(s):  
Jeff Liston ◽  
Anthony E Maltese
Keyword(s):  
Late Cretaceous ◽  
Axial Skeleton ◽  
Upper Jurassic ◽  
Suspension Feeding ◽  
Adult Size ◽  
Skull Morphology ◽  
Poor Knowledge ◽  
Preservation Potential ◽  
Working Out ◽  
Skeletal Ossification

A focus on cranial characters for determining relatedness is a predominant trait in many datasets, however this overemphasis can lead to distortion from sampler bias. We report on revised analyses of pachycormids - a key group within Actinopterygii, as part of the Holostei-Teleostei transition, which display a phyletic trend towards reduced skeletal ossification with the increased adult size of a pachycormid taxon. This reduced preservation potential for the axial skeleton makes it difficult not to base phylogenetic assumptions primarily on the limited skull material present. However, pachycormids show a remarkable conservatism in their dermatocranial anatomy, the few differences being useful for showing the separation of genera, but of little utility in working out broader intrafamilial relationships. The combination of a paucity of postcranial characters in the Late Cretaceous pursuit predator Protosphyraena with a poor knowledge about the skulls of suspension-feeding pachycormids (SFPs) had led to the absence of Early Cretaceous predatory pachycormids being interpreted as indicating a ghost lineage between Protosphyraena and the European Upper Jurassic taxa Orthocormus and Hypsocormus over an almost 50-million-year gap. However, the inclusion of several features from the pectoral and pelvic fins, supplemented by splanchnocranial characters, produces a much clearer picture that questions the traditional perception of a single carnivore lineage: Protosphyraena emerges as secondarily carnivorous from the SFPs’ tribe, mirroring 130 years of misidentification of North American Bonnerichthys specimens as Protosphyraena. Confirmation of this will rely on the further recovery of data concerning the skull morphology of SFPs.

scholarly journals Hips, tips and sweet sweptback rays: Looking beyond traditional cranial characters in Pachycormiformes

2017 ◽  
Author(s):  
Jeff Liston ◽  
Anthony E Maltese
Keyword(s):  
Late Cretaceous ◽  
Axial Skeleton ◽  
Upper Jurassic ◽  
Suspension Feeding ◽  
Adult Size ◽  
Skull Morphology ◽  
Poor Knowledge ◽  
Preservation Potential ◽  
Working Out ◽  
Skeletal Ossification

A focus on cranial characters for determining relatedness is a predominant trait in many datasets, however this overemphasis can lead to distortion from sampler bias. We report on revised analyses of pachycormids - a key group within Actinopterygii, as part of the Holostei-Teleostei transition, which display a phyletic trend towards reduced skeletal ossification with the increased adult size of a pachycormid taxon. This reduced preservation potential for the axial skeleton makes it difficult not to base phylogenetic assumptions primarily on the limited skull material present. However, pachycormids show a remarkable conservatism in their dermatocranial anatomy, the few differences being useful for showing the separation of genera, but of little utility in working out broader intrafamilial relationships. The combination of a paucity of postcranial characters in the Late Cretaceous pursuit predator Protosphyraena with a poor knowledge about the skulls of suspension-feeding pachycormids (SFPs) had led to the absence of Early Cretaceous predatory pachycormids being interpreted as indicating a ghost lineage between Protosphyraena and the European Upper Jurassic taxa Orthocormus and Hypsocormus over an almost 50-million-year gap. However, the inclusion of several features from the pectoral and pelvic fins, supplemented by splanchnocranial characters, produces a much clearer picture that questions the traditional perception of a single carnivore lineage: Protosphyraena emerges as secondarily carnivorous from the SFPs’ tribe, mirroring 130 years of misidentification of North American Bonnerichthys specimens as Protosphyraena. Confirmation of this will rely on the further recovery of data concerning the skull morphology of SFPs.

Capture of conspecific planktonic larvae by the suspension-feeding gastropod Crepipatella peruviana: association between adult and larval size

2021 ◽  
Vol 87 (1) ◽  
Author(s):  
G A Rivera-Figueroa ◽  
J A Büchner-Miranda ◽  
L P Salas-Yanquin ◽  
J A Montory ◽  
V M Cubillos ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Larval Mortality ◽  
Feeding Preference ◽  
The Other ◽  
Suspension Feeding ◽  
Adult Size ◽  
Free Living ◽  
Larval Size ◽  
Suspension Feeders ◽  
Planktonic Larvae

ABSTRACT Free-living, planktonic larvae can be vulnerable to capture and ingestion by adult suspension-feeders. This is particularly the case for larvae that settle gregariously in benthic environments where suspension-feeders occur at high densities. Larvae of gregarious suspension-feeding species are at particularly high risk, as adults of their own species often serve as cues for metamorphosis. We conducted laboratory experiments to assess the extent to which adults of the suspension-feeding caenogastropod Crepipatella peruviana would capture and ingest their own larvae. Experiments were conducted with adults of different sizes, with larvae of different ages and sizes, and in the presence or absence of phytoplankton. Adults captured larvae in all experiments. The presence of microalgae in the water did not influence the extent of larval capture. On average, 39% of larvae were captured during the 3-h feeding periods, regardless of adult size. However, up to 34% of the larvae that were captured on the gill were later discarded as pseudofaeces; the other 64% were ingested. The extent of capture by adults was not related to adult size, or to larval size and, thus, to larval age. Our results suggest that the filtration of congeneric larvae by adult C. peruviana is a result of accidental capture rather than a deliberate feeding preference. Such ingestion could, however, still be an important source of larval mortality, especially when the advanced larvae of this species are searching for a suitable substrate for metamorphosis.

THE REGIONAL GEOLOGY OF THE BONAPARTE GULF TIMOR SEA AREA

1974 ◽  
Vol 14 (1) ◽  
pp. 77 ◽  
Author(s):  
Robert A. Laws ◽  
Gregory P. Kraus
Keyword(s):  
Late Cretaceous ◽  
Late Jurassic ◽  
Oil And Gas ◽  
Upper Jurassic ◽  
Structural Configuration ◽  
Structural Pattern ◽  
Source Areas ◽  
Timor Sea ◽  
Early Palaeozoic ◽  
Sea Area

The present structural configuration of the Bonaparte Gulf-Timor Sea area is essentially the result of Mesozoic and Tertiary fragmentation of a once relatively simple Permo-Triassic Basin. A northwest-southeast Palaeozoic structural grain in the southeastern portion of the area resulted from early Palaeozoic faulting, possibly tied to aborted rift development. This faulting effectively controlled sedimentation throughout the Phanerozoic. Pronounced northeast-southwest Jurassic to Tertiary structural trends dominate the central and northern area, paralleling the present edge of the continental shelf and swinging south southwest into the northern extension of the Browse Basin. Post-Palaeozoic epeirogenies which had the greatest effect on the regional structural pattern occurred in the mid-Jurassic, Early Cretaceous, within the Eocene and in the Plio-Pleistocene.The Kimberley and Sturt Blocks flanking the basin to the south and east constituted the most important source areas for clastic sedimentation throughout the Phanerozoic. Periodic contributions during the Mesozoic were derived from a postulated source to the northwest in the vicinity of the present-day Timor Trough.The maximum thickness of Phanerozoic sediments present within the Bonaparte Gulf-Timor Sea area exceeds 50,000 ft (15,000 m). Early Palaeozoic to Carboniferous evaporites, carbonates and clastics are unconformably overlain by a thick sequence of Permian deltaic sediments in the southeastern Bonaparte Gulf Basin. This is succeeded by a Triassic to Middle Jurassic transgressive-regressive clastic sequence, grading northwestward to marginal marine and marine clastics and carbonates. The Permian to mid-Jurassic sediments are unconformably overlain by Upper Jurassic sands and shales, mainly fluvial in the southeast and north, becoming more marine westward. These clastics are everywhere succeeded by a monotonous sequence of Cretaceous shales and shaly limestones followed by a generally north to northwesterly thickening wedge of Tertiary carbonates and minor elastics.Hydrocarbon shows have been noted offshore in rocks of Carboniferous, Permian, Late Jurassic, Late Cretaceous and Eocene age. Porous clastics in conjunction with thick and laterally-extensive, organically-rich shales are present within the Palaeozoic and Mesozoic sequences. These sediments, in association with fault- and diapir-related anomalies and stratigraphic plays, combine to make certain provinces of the Bonaparte Gulf-Timor Sea area prospective in the search for viable oil and gas reserves.

2D Numerical Simulation of Intraoceanic Subduction during the Upper Jurassic Closure of the Vardar Tethys

2020 ◽  
Author(s):  
Nikola Stanković ◽  
Vesna Cvetkov ◽  
Vladica Cvetković
Keyword(s):  
Numerical Simulations ◽  
Late Cretaceous ◽  
Stokes Equations ◽  
Numerical Models ◽  
Upper Jurassic ◽  
Staggered Grid ◽  
Parameter Study ◽  
Ongoing Research ◽  
Magmatic Complex ◽  
Vardar Zone

<p>In this study we report interim results of our ongoing research that involves the application of numerical modeling for constraining the geodynamic conditions associated with the closure of the Vardar branch of the Tethys Ocean. The study is aimed at better understanding the ultimate fate of the Balkan ophiolites, namely at addressing the question whether these ophiolites represent relicts of an ocean that completely closed during Upper Jurassic/lowermost Cretaceous time (Vardar Tethys) or they also contain remnants of the ocean floor of a Late Cretaceous oceanic realm (Sava – Vardar) [Schmid et al., 2008].</p><p>In our numerical models we try to simulate a single intraoceanic subduction that commences in the Lower/Mid Jurassic and ends in the Lower Cretaceous, transitioning into oceanic closure processes and subsequent collision between Adria and Eurasia plates. These convergent-collision events should have led to the formation of ophiolite-like igneous rocks of the so-called Sava - Vardar zone.</p><p>A series of numerical simulations were performed with varying parameters. In the scope of our numerical simulations, the set of equations is solved: the continuity equation, the Navier-Stokes equations and the temperature equation. Marker in cell method was incorporated in solving this system with finite difference discretization of the equations on a staggered grid. To utilize this numerical method a thermo-mechanical code I2VIS [Gerya et al., 2000; Gerya & Yuen, 2003] was used for obtaining the final results. </p><p>Our actual 2D thermo-mechanical models cover the crust and the upper portion of the mantle with varying starting widths of the Vardar Ocean in the Lower Jurassic. The ocean is modeled with two segments: the western subducting slab and the eastern overriding slab. Slabs with different ages and thicknesses were used and the convergence rate is varied. The intraoceanic subduction is assumed to have been initiated along the mid oceanic ridge. Two continents (i.e. Adria and Eurasia) with different thicknesses of the continental lithosphere and crust are also modeled adjacent to a single oceanic realm between them.</p><p>The parameter study is in function of defining conditions under which the hypothesized scenario occurs. So far, we have succeeded in reproducing westward obduction onto the Adriatic margin, which is in accordance with the geological observations, i.e., with the top-west emplaced West Vardar ophiolites [see Schmid et al., 2008 for references]. However, our model is yet to produce sufficient amounts of back-arc extension along the Eurasian active margin and that is crucial for explaining the formation of the igneous provinces occurring within the Late Cretaceous Sava – Vardar zone and the Timok Magmatic Complex.</p>

Anatomy, systematics, paleoenvironment, growth, and age of the sauropod dinosaur Sonorasaurus thompsoni from the Cretaceous of Arizona, USA

2016 ◽  
Vol 90 (1) ◽  
pp. 102-132 ◽  
Author(s):  
Michael D. D’Emic ◽  
Brady Z. Foreman ◽  
Nathan A. Jud
Keyword(s):  
Life History ◽  
Late Cretaceous ◽  
North American ◽  
Phylogenetic Relationships ◽  
Fossil Record ◽  
Cladistic Analysis ◽  
Detrital Zircons ◽  
Bone Histology ◽  
Seasonal Precipitation ◽  
Adult Size

AbstractSauropod dinosaurs are rare in the Cretaceous North American fossil record in general and are absent from that record for most of the Late Cretaceous. Sonorasaurus thompsoni from the Turney Ranch Formation of the Bisbee Group of Arizona, USA, potentially represents one of the youngest sauropods before their ca. 30-million-year-long hiatus from the record. The anatomy of Sonorasaurus has only been briefly described, its taxonomic validity has been questioned, several hypotheses have been proposed regarding its phylogenetic relationships, and its life history, geologic age, and reported paleoenvironment are ambiguous.Herein we assess the systematics, paleoenvironment, life history, and geologic age of Sonorasaurus based on firsthand observation, bone histology, and fieldwork in the holotypic quarry and environs. The validity of S. thompsoni is substantiated by autapomorphies. Cladistic analysis firmly places it within the Brachiosauridae, in contrast to results of some recent analyses. Bone histology suggests that the only known exemplar of Sonorasaurus grew slowly and sporadically compared to other sauropods and was approaching its adult size. In contrast with previous assessments of a coastal/estuarine paleoenvironment for the Turney Ranch Formation, our sedimentological and plant macrofossil data indicate that Sonorasaurus lived in a semiarid, low relief evergreen woodland that received highly variable (perhaps seasonal) precipitation. We obtained detrital zircons from the holotypic quarry for U-Pb dating, which only yielded Barremian-aged and older grains, whereas other radiometric and biostratigraphic data suggest that the sediments at the quarry were deposited near the Albian-Cenomanian boundary.Sonorasaurus is taxonomically valid, represents one of the geologically youngest brachiosaurid sauropods, and inhabited a harsh inland evergreen-dominated woodland environment that limited its growth. A review of other Bisbee Group dinosaurs suggests that its fauna, although poorly sampled, exhibits broad similarity to those from coeval North American horizons, reinforcing the apparent faunal homogeneity at the time.

THE AXIAL SKELETON OF RINCONSAURUS CAUDAMIRUS (SAUROPODA: TITANOSAURIA) FROM THE LATE CRETACEOUS OF PATAGONIA, ARGENTINA

Ameghiniana ◽  
2021 ◽  
Author(s):  
Agustín Pérez-Moreno ◽  
José Carballido ◽  
Alejandro Otero ◽  
Leonardo Salgado ◽  
Jorge Calvo
Keyword(s):  
Late Cretaceous ◽  
Axial Skeleton

Paleogeographie, orogenese, metamorphisme et magmatisme des zones internes des Hellenides en Macedoine (Grece); vue d'ensemble

1966 ◽  
Vol S7-VIII (7) ◽  
pp. 1020-1049 ◽  
Author(s):  
Jacques Mercier
Keyword(s):  
Early Cretaceous ◽  
Late Cretaceous ◽  
Middle Eocene ◽  
Upper Jurassic ◽  
Upper Eocene ◽  
Vertical Movements ◽  
Lower Oligocene ◽  
Upper Paleozoic ◽  
Igneous Activity ◽  
Two Phases

Abstract Since the end of major Hercynian disturbances in the upper Paleozoic, the inner Hellenide zones, including the Peonia and Almopia troughs and the Paikon and Pelagonian ridges, have been affected by several periods of complex orogenic activity among which were four phases of tangential movements: Portlandian or terminal early Cretaceous, terminal Cretaceous to lower-middle Eocene, latest Priabonian, and post-lower Oligocene. Vertical movements took place before the last tangential phases, during Kimmeridgian-Portlandian and Turonian-Campanian time. Since the Hercynian and pre-Hercynian periods of metamorphism the inner Hellenides have been affected by dynamic metamorphism of post-Jurassic-pre-Albian-Aptian and post-Maestrichtian-pre-lower Oligocene age; post-middle-upper Eocene dynamic metamorphism had localized effects near structural contacts. Igneous activity associated with the metamorphism and orogenic movements was initially (Jurassic) ophiolitic; two phases of synorogenic (upper Jurassic-early Cretaceous and late Cretaceous to lower-middle Eocene) granitic activity followed and were in turn succeeded by three phases of postorogenic (Plio-Quaternary) andesitic, granitic-granodioritic, and basaltic activity.

Geographic and stratigraphic distribution of the Late Cretaceous suspension-feeding bony fishBonnerichthys gladius(Teleostei, Pachycormiformes)

2013 ◽  
Vol 33 (1) ◽  
pp. 35-47 ◽  
Author(s):  
Matt Friedman ◽  
Kenshu Shimada ◽  
Michael J. Everhart ◽  
Kelly J. Irwin ◽  
Barbara S. Grandstaff ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Suspension Feeding
Sign in / Sign up

Export Citation Format

Share Document