Ben Creisler
Some recent non-dino papers:
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Robert J. Brocklehurst, Sabine Moritz, Jonathan Codd, William I. Sellers & Elizabeth L. Brainerd (2019)
XROMM kinematics of ventilation in wild turkeys (Meleagris gallopavo).
Journal of Experimental Biology 222: jeb209783
doi: 10.1242/jeb.209783
https://jeb.biologists.org/content/222/23/jeb209783The avian ribcage is derived relative to other amniotes, and is hypothesised to be constrained in its movements during ventilation. The double-headed ribs form two articulations with the vertebrae, and are thought to rotate about a strict anatomical axis. However, this costovertebral joint constraint has not been demonstrated empirically and was not found in other taxa with double-headed ribs (i.e. crocodilians). Here, we used X-ray reconstruction of moving morphology (XROMM) to quantify rib rotation in wild turkeys (Meleagris gallopavo) during breathing. We demonstrate that, as predicted from anatomy, the ribs do rotate in a hinge-like manner about a single axis. There is also evidence for elliptical motion of the sternum, as has been reported in other taxa. The evolution of the avian ribcage is closely related to the co-evolution of ventilation and flight, and these results are important for how we model ventilation mechanics in living and fossil birds.
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Juan Alberto PÃrez-Valera, MÃlani Berrocal-Casero & Fernando PÃrez-Valera (2019)
First Triassic tetrapod (Eusauropterygia) in the Triassic of the Subbetic domain of the Betic Cordillera (Southeastern Spain).
PalZ (advance online publication)
DOI:
https://doi.org/10.1007/s12542-019-00500-yhttps://link.springer.com/article/10.1007/s12542-019-00500-ySauropterygian vertebrate remains from the Ladinian (Middle Triassic) of the proximity of Calasparra (Murcia, Spain) are described here. They represent the first documented Triassic vertebrate remains found in the Province of Murcia, and the first in the Subbetic domain of the Betic Cordillera (Southeastern Spain). These new remains consist of incomplete vertebrae, some fragmented neural spine apophyses, fragments of transverse processes, a partial thoracic vertebrae mould and one isolated thoracic vertebral centrum, seemingly of a single specimen. Their features permit to refer them to the suborder Eusauropterygia. These fossils have been found in the middle part of the upper member of the CehegÃn Formation. The biostratigraphical framework of the CehegÃn Formation consists of a relatively abundant fossil content that allowed its attribution to the uppermost Fassanian (Lower Ladinian). The sedimentary features and the palaeontological content of the site are typical of an epicontinental platform.
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http://sciencepress.mnhn.fr/sites/default/files/articles/pdf/g2019v41a24.pdfLizard material from the early Oligocene and early and late Miocene of the Valley of Lakes, Central Mongolia is described. Besides the Oligocene fossorial squamate published elsewere, the material can be allocated to several major clades: Agamidae, Lacertidae and Anguidae (Glyptosaurinae). The presence of Pseudotinosaurus Alifanov, 1991 in early and late Rupelian localities shows that this taxon has a continuous history in this area from the Eocene to the Oligocene. The same is true for the clade Glyptosaurinae, represented by isolated osteoderms in the early Oligocene locality Hsanda Gol. This might suggest that the Eocene-Oligocene transition did not have such a strong or rapid impact in East Asia, in contrast to the Grande Coupure in Europe, at least among some lizard clades. The early Oligocene (early Rupelian) lacertids from Taatsiin Gol, Hsanda Gol and Tatal Gol represent one of the oldest evidences of Asiatic dispersal of this clade. It might reflect the dispersal pathways after closure of the Turgai Strait between Europe and Asia. Some of the material closely resembles the common European Oligocene taxon Lacerta s.l. filholi AugÃ, 1988. In the early Miocene locality Olon Ovoony Khurem, two clades can be recognized â Lacertidae and a scincoid with a specialized dentition (family indeterminate). The clade Lacertidae forms a dominant component of the late Miocene lizard fossils in Mongolia. The material from the locality Builstyn Khudag shows differences compared to the early Miocene lacertids and represents the oldest evidence of the tribe Eremiadini in this area.
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Nuria Melisa Morales-GarcÃa, Thomas D. Burgess, Jennifer J. Hill, Pamela G. Gill and Emily J. Rayfield (2019)
The use of extruded finite-element models as a novel alternative to tomography-based models: a case study using early mammal jaws.
Journal of the Royal Society Interface 16: 20190674
doi:
http://dx.doi.org/10.1098/rsif.2019.0674https://royalsocietypublishing.org/doi/10.1098/rsif.2019.0674Free pdf:
https://royalsocietypublishing.org/doi/pdf/10.1098/rsif.2019.0674Finite-element (FE) analysis has been used in palaeobiology to assess the mechanical performance of the jaw. It uses two types of models: tomography-based three-dimensional (3D) models (very accurate, not always accessible) and two-dimensional (2D) models (quick and easy to build, good for broad-scale studies, cannot obtain absolute stress and strain values). Here, we introduce extruded FE models, which provide fairly accurate mechanical performance results, while remaining low-cost, quick and easy to build. These are simplified 3D models built from lateral outlines of a relatively flat jaw and extruded to its average width. There are two types: extruded (flat mediolaterally) and enhanced extruded (accounts for width differences in the ascending ramus). Here, we compare mechanical performance values resulting from four types of FE models (i.e. tomography-based 3D, extruded, enhanced extruded and 2D) in Morganucodon and Kuehneotherium. In terms of absolute values, both types of extruded model perform well in comparison to the tomography-based 3D models, but enhanced extruded models perform better. In terms of overall patterns, all models produce similar results. Extruded FE models constitute a viable alternative to the use of tomography-based 3D models, particularly in relatively flat bones.
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J. A. Goldbogen, D. E. Cade, D. M. Wisniewska, J. Potvin, P. S. Segre, M. S. Savoca, E. L. Hazen, M. F. Czapanskiy, S. R. Kahane-Rapport, S. L. DeRuiter, S. Gero, P. TÃnnesen, W. T. Gough, M. B. Hanson, M. M. Holt, F. H. Jensen, M. Simon, A. K. Stimpert, P. Arranz, D. W. Johnston, D. P. Nowacek, S. E. Parks, F. Visser, A. S. Friedlaender, P. L. Tyack, P. T. Madsen & N. D. Pyenson (2019)
Why whales are big but not bigger: Physiological drivers and ecological limits in the age of ocean giants.
Science 366(6471): 1367-1372
DOI: 10.1126/science.aax9044
https://science.sciencemag.org/content/366/6471/1367.abstract
It's the prey that matters
Although many people think of dinosaurs as being the largest creatures to have lived on Earth, the true largest known animal is still here today--the blue whale. How whales were able to become so large has long been of interest. Goldbogen et al. used field-collected data on feeding and diving events across different types of whales to calculate rates of energy gain (see the Perspective by Williams). They found that increased body size facilitates increased prey capture. Furthermore, body-size increase in the marine environment appears to be limited only by prey availability.
Abstract
The largest animals are marine filter feeders, but the underlying mechanism of their large size remains unexplained. We measured feeding performance and prey quality to demonstrate how whale gigantism is driven by the interplay of prey abundance and harvesting mechanisms that increase prey capture rates and energy intake. The foraging efficiency of toothed whales that feed on single prey is constrained by the abundance of large prey, whereas filter-feeding baleen whales seasonally exploit vast swarms of small prey at high efficiencies. Given temporally and spatially aggregated prey, filter feeding provides an evolutionary pathway to extremes in body size that are not available to lineages that must feed on one prey at a time. Maximum size in filter feeders is likely constrained by prey availability across space and time.
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Terrie M. Williams (2019)
The biology of big
Science 366(6471): 1316-1317
DOI: 10.1126/science.aba1128
https://science.sciencemag.org/content/366/6471/1316Summary
With so many recent scientific advances focused on the mini, micro, nano, and molecular scales, there is a tendency to overlook the titanic biology of giants that share the Earth. The sheer magnitude of a scientific undertaking to study an oceanic, 25-m-long, 95,000-kg wild blue whale (Balaenoptera musculus)âthe largest vertebrate in the animal kingdomâhas long left researchers with little more than brief glimpses of their presence when the leviathan surfaces to breathe. On page 1367 of this issue, Goldbogen et al. (1) describe how they took advantage of developments in microprocessor technology to design submersible wildlife tags. The authors used the new tools to measure the feeding performance and prey choices of the largest mammals in the seas. These data revealed the ecological and evolutionary factors that drive the biology of being, not just big, but the biggest everâperhaps the biggest possible.
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Due to a lack of Mesozoic fossil records, the origins and early evolution of feather-feeding behaviors by insects are obscure. Here, we report ten nymph specimens of a new lineage of insect, Mesophthirus engeli gen et. sp. nov. within Mesophthiridae fam. nov. from the mid-Cretaceous (ca. 100 Mya) Myanmar (Burmese) amber. This new insect clade shows a series of ectoparasitic morphological characters such as tiny wingless body, head with strong chewing mouthparts, robust and short antennae having long setae, legs with only one single tarsal claw associated with two additional long setae, etc. Most significantly, these insects are preserved with partially damaged dinosaur feathers, the damage of which was probably made by these insectsâ integument-feeding behaviors. This finding demonstrates that feather-feeding behaviors of insects originated at least in mid-Cretaceous, accompanying the radiation of feathered dinosaurs including early birds.
News:
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https://www.nature.com/articles/s41598-019-55162-2.pdfThe end-Triassic mass extinction (ETE) is associated with a rise in CO2 due to eruptions of the Central Atlantic Magmatic Province (CAMP), and had a particularly dramatic effect on the Modern Fauna, so an understanding of the conditions that led to the ETE has relevance to current rising CO2 levels. Here, we report multiple phosphorite deposits in strata that immediately precede the ETE at Williston Lake, Canada, which allow the paleoenvironmental conditions leading up to the mass extinction to be investigated. The predominance of phosphatic coated grains within phoshorites indicates reworking in shallow water environments. Raman spectroscopy reveals that the phosphorites contain organic carbon, and petrographic and scanning electron microscopic analyses reveal that the phosphorites contain putative microfossils, potentially suggesting microbial involvement in a direct or indirect way. Thus, we favor a mechanism of phosphogenesis that involves microbial polyphosphate metabolism in which phosphatic deposits typically form at the interface of euxinic/anoxic and oxic conditions. When combined with data from deeper water deposits (Kennecott Point) far to the southwest, it would appear a very broad area of northeastern Panthalassa experienced anoxic to euxinic bottom water conditions in the direct lead up to the end-Triassic mass extinction. Such a scenario implies expansion and shallowing of the oxygen minimum zone across a very broad area of northeastern Panthalassa, which potentially created a stressful environment for benthic metazoan communities. Studies of the pre-extinction interval from different sites across the globe are required to resolve the chronology and spatial distribution of processes that governed before the major environmental collapse that caused the ETE. Results from this study demonstrate that fluctuating anoxic and euxinic conditions could have been potentially responsible for reduced ecosystem stability before the onset of CAMP volcanism, at least at the regional scale.
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L. E. Augland, V. V. Ryabov, V. A. Vernikovsky, S. Planke, A. G. Polozov, S. Callegaro, D. A. Jerram & H. H. Svensen (2019)
The main pulse of the Siberian Traps expanded in size and composition.
Scientific Reports 9, Article number: 18723
doi:
https://doi.org/10.1038/s41598-019-54023-2https://www.nature.com/articles/s41598-019-54023-2Free pdf:
https://www.nature.com/articles/s41598-019-54023-2.pdfEmplacement of large volumes of (sub)volcanic rocks during the main pulse of the Siberian Traps occurred within <1âm.y., coinciding with the end-Permian mass extinction. Volcanics from outside the main Siberian Traps, e.g. Taimyr and West Siberia, have since long been correlated, but existing geochronological data cannot resolve at a precision better than ~5âm.y. whether (sub)volcanic activity in these areas actually occurred during the main pulse or later. We report the first high precision U-Pb zircon geochronology from two alkaline ultramafic-felsic layered intrusive complexes from Taimyr, showing synchronicity between these and the main Siberian Traps (sub)volcanic pulse, and the presence of a second Dinerian-Smithian pulse. This is the first documentation of felsic intrusive magmatism occurring during the main pulse, testifying to the Siberian Trapâs compositional diversity. Furthermore, the intrusions cut basal basalts of the Taimyr lava stratigraphy hence providing a minimum age of these basalts of 251.64âÂâ0.11âMa. Synchronicity of (sub)volcanic activity between Taimyr and the Siberian Traps imply that the total area of the Siberian Traps main pulse should include a ~300 000 km2 area north of Norilsk. The vast aerial extent of the (sub)volcanic activity during the Siberian Traps main pulse may explain the severe environmental consequences.