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[dinosaur] Cortical canals in bone + Brasilichnium saltatorium tracks + extinctions




Ben Creisler
bcreisler@gmail.com


Some recent non-dino papers that may be of interest:

This one has a free pdf:

Isaac Vorster Pratt & David Michael Lane Cooper (2016)
A method for measuring the three-dimensional orientation of cortical canals with implications for comparative analysis of bone microstructure in vertebrates.
Micron (advance online publication)
doi: http://dx.doi.org/10.1016/j.micron.2016.10.006
http://www.sciencedirect.com/science/article/pii/S0968432816301585

Highlights

The orientation of cortical canals is believed to be related to bone growth and functional loading.
We present here a new method for measuring the orientation of cortical canals.
We show the application of this method in a mammal and a bird.
This method can be used to study bones from any vertebrate, including mammals, reptiles, and birds

Abstract

The orientation of vascular canals in cortical bone can reveal information about the growth rate and loading environment of a bone. For example, in birds it has been proposed that a high proportion of circumferential canals (a laminar cortex) is related to fast growth or torsional loading related to active flight. In this paper we present a method to measure the three dimensional (3D) orientation of vascular canals. Image data are obtained from micro-CT and two angles are measured: phi, determining how longitudinal a canal is; and theta, determining whether a canal is radial or circumferential. This method can measure the orientation of each canal contained in the scanned images. Here we demonstrate the approach on two samples − a rat tibia and a hawk humerus. This method offers a direct (3D) method for quantifying features of canal orientation, such as the degree of laminarity, and can be applied easily and non-destructively to multiple species and bones. The growth and development of the cortical canal network and its impact on factors such as bone strength and bone quality remains relatively unexplored. Our method provides a new tool to examine the impact of the orientation of cortical bone canals on bone and explore the origins of cortical canals formed during modelling and remodeling. This method has applications in comparative bone biology, small animal models, and human bone studies.


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Some other recent papers that may be of interest (not free)

Brasilichnium saltatorium isp. nov


Pedro Victor Buck, Aline Marcele Ghilardi, Bernardo de C. P. e M. Peixoto, Luciana Bueno dos Reis Fernandes & Marcelo Adorna Fernandes (2016)
A new tetrapod ichnotaxon from Botucatu formation, Lower Cretaceous (Neocomian), Brazil, with comments on fossil track preservation on inclined planes and local paleoecology.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
doi: http://dx.doi.org/10.1016/j.palaeo.2016.11.009
http://www.sciencedirect.com/science/article/pii/S0031018216306940

Highlights

Brasilichnium saltatorium isp. nov., a new tetrapod ichnospecies with saltatorial locomotion is described.
The new ichnotaxon can be associated to a mammaliform producer.
Brasilichnium saltatorium isp. nov. and B. elusivum could be produced by the same organism.
Neoichnological experiments corroborates differences in parameters between different directions of movement in fossil trackways.
Brasilichnium producer was likely a generalist organism with omnivorous and fossorial habits.
São Bento quarry paleoenviroment had local high humidity and sustained an abundant paleofauna.

Abstract

Botucatu Formation is a paleoerg, worldwide famous for its vertebrate and invertebrate ichnofossils. Among Botucatu Formation tetrapod tracks, ichnogenus Brasilichnium Leonardi, 1981 is well known, being generally attributed to mammaliform trackmakers. In this study a new ichnotaxon is described, Brasilichnium saltatorium isp. nov., characterized by a hopping locomotion in phases. The new ichnotaxon differs from B. elusivum Leonardi, 1981 mainly for the locomotion pattern. It also differs from other ichnotaxa by indicating hopping progression regarding limb morphology and track configuration. Fossil evidence shows B. saltatorium and B. elusivum could be produced by the same organism and represent an alternation in locomotory behavior. Neoichnological experiments were conducted to better understand track preservation and aspects of saltatorial dynamics on inclined planes. It was observed differences in heteropody degree may be related to movement direction and locomotion effort on ascending or descending the incluned plane. Due to extramorphological features, heteropody is more evident when the producer climbs the simulated dune. Also, when the movement is ascendent, lack of handprints can occur. This can be explained by total overlap of pes and manus impression and subsurface hand impression. Comparing with recent organisms living in similar environments and conditions, the Botucatu Formation B. saltatorium producer should have been a generalist organism likely with an omnivorous habit. It may have adopted hopping locomotion to gain velocity when hunting, escaping predators, or to facilitate progression on inclined planes and hot sand. São Bento quarry represents a paleodesert environment with relative high humidity, where temporary lagoons may have formed during pluvial events. Paleo-rain episode evidence is preserved through raindrops impact craters on local sandstone. São Bento quarry paleoenvironment sustained a rich paleofauna, represented by abundant ichnofossils. This local diversity suggests a punctual productive desert paleocommunity with several paleoecological interactions, where Brasilichnium producer was one of the fundamental elements.

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Extinction stuff:


David P.G. Bond & Stephen E. Grasby (2016)
On the causes of mass extinctions.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
doi: http://dx.doi.org/10.1016/j.palaeo.2016.11.005
http://www.sciencedirect.com/science/article/pii/S0031018216306915

Highlights

The temporal link between large igneous provinces and extinctions implies causality
Many extinctions are associated with volcanogenic warming, anoxia and acidification.
Terrestrial and marine extinctions are driven by a link: atmospheric processes.
Atmospheric killers include toxic metal poisoning, acid rain, O3 damage and UV-B radiation.
Continental configuration might govern LIP lethality with Pangaea being important.
Experimental biology might inform our understanding of past and future extinctions.

Abstract

The temporal link between large igneous province (LIP) eruptions and at least half of the major extinctions of the Phanerozoic implies that large scale volcanism is the main driver of mass extinction. Here we review almost twenty biotic crises between the early Cambrian and end Cretaceous and explore potential causal mechanisms. Most extinctions are associated with global warming and proximal killers such as marine anoxia (including the Early/Middle Cambrian, the Late Ordovician, the intra-Silurian, intra-Devonian, end-Permian, and Early Jurassic crises). Many, but not all of these are accompanied by large negative carbon isotope excursions, supporting a volcanogenic origin. Most post-Silurian biocrises affected both terrestrial and marine biospheres, suggesting that atmospheric processes were crucial in driving global extinctions. Volcanogenic-atmospheric kill mechanisms include ocean acidification, toxic metal poisoning, acid rain, and ozone damage and consequent increased UV-B radiation, volcanic darkness, cooling and photosynthetic shutdown, each of which has been implicated in numerous events. Intriguingly, some of the most voluminous LIPs such as the oceanic plateaus of the Cretaceous were emplaced with minimal faunal losses and so volume of magma is not the only factor governing LIP lethality. The missing link might be continental configuration because the best examples of the LIP/extinction relationship occurred during the time of Pangaea. Many of the proximal kill mechanisms in LIP/extinction scenarios are also potential effects of bolide impact, including cooling, warming, acidification and ozone destruction. However, the absence of convincing temporal links between impacts and extinctions other than the Chicxulub-Cretaceous example, suggests that impacts are not the main driver of extinctions. With numerous competing extinction scenarios, and the realisation that some of the purported environmental stresses may once again be driving mass extinction, we explore how experimental biology might inform our understanding of ancient extinctions as well as future crises.


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Stephen E. Grasby, Wenjie Shen, Runsheng Yin, James D. Gleason, Joel D. Blum, Ryan F. Lepak, James P. Hurley, and Benoit Beauchamp (2016)
Isotopic signatures of mercury contamination in latest Permian oceans.
Geology (advance online publication)
doi: 10.1130/G38487.1
http://geology.gsapubs.org/content/early/2016/11/08/G38487.1.abstract

Sedimentary records from the northwest margin of Pangea and the Tethys show anomalously high Hg levels at the latest Permian extinction boundary. Background δ202Hg values are consistent with normal marine conditions but exhibit negative shifts coincident with increased Hg concentrations. Hg isotope mass-independent fractionation (Δ199Hg) trends are consistent with volcanic input in deep-water marine environments. In contrast, nearshore environments have Δ199Hg signatures consistent with enhanced soil and/or biomass input. We hypothesize that the deep-water signature represents an overall global increase in volcanic Hg input and that this isotope signature is overwhelmed in nearshore locations due to Hg from terrestrial sources. High-productivity nearshore regions may have experienced stressed marine ecosystems due to enhanced Hg loading.

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Claudio Garbelli, Lucia Angiolini, and Shu-zhong Shen (2016)
Biomineralization and global change: A new perspective for understanding the end-Permian extinction.
Geology (advance online publication) 
doi:10.1130/G38430.1
http://geology.gsapubs.org/content/early/2016/11/08/G38430.1.abstract

We investigated the kill mechanisms of the end-Permian mass extinction by analyzing patterns in biomineralization of marine invertebrates. The microstructures of Upper Permian brachiopod organocarbonate shells show the demise of the production of fabrics with a columnar layer—which has less organic matrix—in favor of more organic-rich shells at the end of Permian. Also, in the 100–120 k.y. interval prior to the Permian-Triassic boundary (PTB), the Rhynchonellata had small calcite structural units (fibers) and thus a higher shell organic content, whereas the Strophomenata were not able to produce smaller units. This suggests that the two classes had a different capacity to cope with environmental change, with the Rhynchonellata being more able to buffer against pH changes and surviving the PTB, whereas the Strophomenata became extinct. The observed trends in biomineralization are similar to the patterns in extant marine invertebrates exposed to increasing pCO2 and decreasing pH, indicating that ocean acidification could have been one of the kill mechanisms of the mass extinction at the PTB.

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Guillaume Charbonnier and Karl B. Föllmi (2016)
Mercury enrichments in lower Aptian sediments support the link between Ontong Java large igneous province activity and oceanic anoxic episode 1a.
Geology (advance online publication) 
doi:10.1130/G38207.1
http://geology.gsapubs.org/content/early/2016/11/08/G38207.1.abstract


The early Aptian recorded one of the most significant episodes of environmental change during the Mesozoic—the Selli oceanic anoxic episode (OAE 1a). It has often been suggested that magmatic activity related to the emplacement of the Greater Ontong Java large igneous province (LIP) triggered OAE 1a. A major challenge, however, resides in the establishment of precise temporal relationships between the environmental perturbations associated with OAE 1a and the phases of volcanic activity. In this study, we evaluate the potential of mercury (Hg) as a proxy of volcanic activity and investigate lower Aptian sediments with different total organic carbon (TOC) contents, which are exposed at Roter Sattel (Briançonnais, Swiss Alps), Glaise (Vocontian Basin, southeast France), and La Bédoule (South Provencal Basin, southeast France). The intervals equivalent to OAE 1a are marked by significant increases in Hg contents, which are only partially dependent on TOC contents. This is shown by the Hg anomalies in the TOC-poor sediments of La Bédoule, the only moderate correlation of Hg and TOC contents in the TOC-enriched sediments of Roter Sattel (R2 = 0.48), and the persistence of the anomaly in Hg/TOC ratios in all sediments except for the TOC-enriched ones. These results suggest that the Hg anomaly not only is related to primary productivity, redox conditions, and organic-matter preservation, but has deeper roots. Volcanic outgassing related to Greater Ontong Java LIP activity is taken here as the main source of the Hg enrichment recorded in the western Tethyan sediments. Our Hg data indicate that magmatic pulses at the onset and during the OAE 1a triggered the early Aptian environmental perturbations.