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[dinosaur] Endothermic mosasaurs? (free pdf) + marine Nanzhang-Yuan′an Fauna from Lower Triassic of China + more papers




Ben Creisler
bcreisler@gmail.com


Some recent non-dino papers:

T. Lynn Harrell, Jr,, Alberto Pérez-Huerta and Celina A. Suarez (2016)
Endothermic mosasaurs? Possible thermoregulation of Late Cretaceous mosasaurs (Reptilia, Squamata) indicated by stable oxygen isotopes in fossil bioapatite in comparison with coeval marine fish and pelagic seabirds.
Palaeontology (advance online publication)
DOI: 10.1111/pala.12240
http: // onlinelibrary.wiley.com/doi/10.1111/pala.12240/abstract

Free pdf:

http: // onlinelibrary.wiley.com/doi/10.1111/pala.12240/epdf



The thermoregulatory style of Late Cretaceous mosasaurs has become a highly controversial subject in vertebrate palaeontology. These extinct marine reptiles have previously been described as poikilothermic, endothermic or gigantothermic. Here we analyse three genera of mosasaurs from the Mooreville Chalk in Alabama (USA) of differing body mass, and compare their δ18OPO4 derived body temperatures (Tb) with those of coeval poikilothermic fish (Enchodus) and endothermic pelagic seabirds (Ichthyornis). Results show that all mosasaurs, Clidastes (Tb = 33.1°C), Platecarpus (Tb = 36.3°C), and Tylosaurus (Tb = 34.3°C), had elevated average body temperatures in relation to those of the fish (Tb = 28.3°C) and were closer to those of Ichthyornis (Tb = 38.6°C). The temperatures calculated for Enchodus compare well with previously reported temperature estimates for the Mooreville Chalk and the Tb of Ichthyornis compares well with temperatures that have been reported for modern seabirds, suggesting that this method provides accurate results. Finally, although there are small differences of body temperature among mosasaur genera, these are independent of size, and thus inferred body mass, suggesting that mosasaurs were not gigantotherms, but rather endotherms.


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Chen Can, Chen Xiaohong, Cheng Long & Yan Chunbo (2016)     

Nanzhang-Yuan′an Fauna, Hubei Province and Its Significance for Biotic Recovery.

Acta Geologica Sinica 90(3): 409-420 (Chinese Edition)

http: // www.geojournals.cn/dzxb/ch/reader/view_abstract.aspx?file_no=2014033&flag=1


Free pdf:

 

http: // www.geojournals.cn/dzxb/ch/reader/download_pdf.aspx?file_no=2014033&year_id=2016&quarter_id=3&falg=1

 

[NOTE: This pdf may be slow to download.]


The upper part of the Third Member of the Lower Triassic Jialingjiang Formation in western Hubei Province was composed of laminated limestone with 30 meters thickness. It contains many kinds of marine reptile fossils including such as Hupehsuchia, Ichthyosauria and Sauropterygia and others from Yingzishan, Yangping of Yuan’an county to Xunjian, Gujin of Nanzhang county in western Hubei Province. These marine reptiles formed an excellent Nanzhang-Yuan’an fauna characterized by occurrence of abundant Hupehsuchia, which coexisted with Ichthyosauria and Sauropterygia. This fauna indicated that the first radiation of marine reptiles happened and a new ocean ecosystem rebuilt by marine reptiles was formed in the late Early Triassic because its diversities of the Order or genus and species of the marine reptiles were close to that of the Panxian-Luoping fauna which used to be regarded as a typical fauna occurred after biotic recovery in the Middle Triassic.



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Abdelouahed Lagnaoui, Hendrik Klein, Hafid Saber, Abdelilah Fekkak, Abouchouaïb Belahmira & Joerg.W. Schneider (2016)

New discoveries of archosaur and other tetrapod footprints from the Timezgadiouine Formation (Irohalene Member, Upper Triassic) of the Argana Basin, western High Atlas, Morocco — Ichnotaxonomic implications.

Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)

doi:10.1016/j.palaeo.2016.03.022

http: // www.sciencedirect.com/science/article/pii/S0031018216300359


Highlights


New discoveries of Late Triassic tetrapod footprints from Morocco.

Ichnotaxonomic re-evaluation of footprints described earlier from the Late Triassic deposits of Morocco.

The second record of the ichnogenus Brachychirotherium in North Africa and Morocco.


Abstract


New discoveries of tetrapod footprints from the Irohalene Member (T5, Upper Triassic, Carnian) of the Timezgadiouine Formation near Irohalene (Argana Basin, Morocco) are assigned to Parachirotherium isp., Atreipus-Grallator isp. (Dinosauromorpha), Brachychirotherium isp. (crocodylian-stem archosaurs), Apatopus lineatus (phytosaurs) and Rhynchosauroides (lepidosauromorphs/archosauromorphs). Parachirotherium is present on the surfaces with different tetradactyl–pentadactyl extramorphological variations, similar to the preservation mode observed at the type locality of the ichnogenus in the Middle Triassic of the European Germanic Basin. Described specimens permit a re-evaluation of footprints described earlier from the Irohalene locality that are synonymized here with Parachirotherium and Atreipus-Grallator. The presence of Brachychirotherium is the second record in North Africa and Morocco. The assemblage is similar in composition to other T5 localities and to some ichnofaunas in North America and central Europe. Biostratigraphically, the occurrence of Brachychirotherium indicates the respective biochron that can be cross-correlated with the Carnian–Rhaetian interval.



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Jeong Yul Kim & Martin Lockley (2016)

First Report of Turtle Tracks from the Lower Cretaceous of Korea

Cretaceous Research (advance online publication)

doi:10.1016/j.cretres.2016.03.014

http: // www.sciencedirect.com/science/article/pii/S0195667116300441


A partial trackway of a turtle from the Jinju Formation (Sindong Group) is the first report of Mesozoic turtle tracks from Korea and the first report of traces of an aquatic tetrapod from Korea. Six tracks show a partial trackway configuration inferred to represent a partially buoyant trackmaker, possibly engaged in “bottom walking” behavior. Although turtle tracks often co-occur with crocodylian tracks in Cretaceous coastal plain facies in other regions, especially North America, to date there are no such co-occurrences in east Asia. This suggests that in Asia paleoenvironments suitable for turtles were quite widespread, but paleoenvironments were not suitable for crocodylians.


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Maria E. McNamara, Patrick J. Orr, Stuart L. Kearns, Luis Alcalá, Pere Anadón & Enrique Peñalver (2016)

Reconstructing Carotenoid-Based and Structural Coloration in Fossil Skin.

Current Biology (advance online publication)

doi:10.1016/j.cub.2016.02.038

http: // www.cell.com/current-biology/fulltext/S0960-9822(16)30120-8


pdf:

http: // www.cell.com/current-biology/pdf/S0960-9822(16)30120-8.pdf


Also:

http: // www.sciencedirect.com/science/article/pii/S0960982216301208

 

Highlights


Dermal pigment cells are preserved in the skin of a fossil snake

This is the first evidence of carotenoid-based and structural color in fossil skin

The distribution and abundance of pigment cells reveals original color patterns

This opens a new avenue for reconstructing original coloration in fossil animals


Summary


Evidence of original coloration in fossils provides insights into the visual communication strategies used by ancient animals and the functional evolution of coloration over time. Hitherto, all reconstructions of the colors of reptile integument and the plumage of fossil birds and feathered dinosaurs have been of melanin-based coloration. Extant animals also use other mechanisms for producing color, but these have not been identified in fossils. Here we report the first examples of carotenoid-based coloration in the fossil record, and of structural coloration in fossil integument. The fossil skin, from a 10 million-year-old colubrid snake from the Late Miocene Libros Lagerstätte (Teruel, Spain), preserves dermal pigment cells (chromatophores)—xanthophores, iridophores, and melanophores—in calcium phosphate. Comparison with chromatophore abundance and position in extant reptiles indicates that the fossil snake was pale-colored in ventral regions; dorsal and lateral regions were green with brown-black and yellow-green transverse blotches. Such coloration most likely functioned in substrate matching and intraspecific signaling. Skin replicated in authigenic minerals is not uncommon in exceptionally preserved fossils, and dermal pigment cells generate coloration in numerous reptile, amphibian, and fish taxa today. Our discovery thus represents a new means by which to reconstruct the original coloration of exceptionally preserved fossil vertebrates.


News:


http: // phys.org/news/2016-03-fossilized-snake-true.html     


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Free pdf:


Eric T. Domyan, Zev Kronenberg, Carlos R. Infante, Anna I. Vickrey, Sydney A, Stringham, Rebecca Bruders, Michael W. Guernsey, Sungdae Park, Jason Payne, Robert B. Beckstead, Gabrielle Kardon, Douglas B. Menke, Mark Yandell & Michael D. Shapiro (2016)

Molecular shifts in limb identity underlie development of feathered feet in two domestic avian species.

eLife 2016;5:e12115

DOI: http: // dx.doi.org/10.7554/eLife.12115

http: // elifesciences.org/content/5/e12115v1#

 

Birds display remarkable diversity in the distribution and morphology of scales and feathers on their feet, yet the genetic and developmental mechanisms governing this diversity remain unknown. Domestic pigeons have striking variation in foot feathering within a single species, providing a tractable model to investigate the molecular basis of skin appendage differences. We found that feathered feet in pigeons result from a partial transformation from hindlimb to forelimb identity mediated by cis-regulatory changes in the genes encoding the hindlimb-specific transcription factor Pitx1 and forelimb-specific transcription factor Tbx5. We also found that ectopic _expression_ of Tbx5 is associated with foot feathers in chickens, suggesting similar molecular pathways underlie phenotypic convergence between these two species. These results show how changes in _expression_ of regional patterning genes can generate localized changes in organ fate and morphology, and provide viable molecular mechanisms for diversity in hindlimb scale and feather distribution.


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Free pdf:


Trevor H. Worthy,  Miyess Mitri,  Warren D. Handley,  Michael S. Y. Lee,  Atholl Anderson & Christophe Sand (2016) 

Osteology Supports a Stem-Galliform Affinity for the Giant Extinct Flightless Bird Sylviornis neocaledoniae (Sylviornithidae, Galloanseres). 

PLoS ONE 11(3): e0150871. 

doi:10.1371/journal.pone.0150871

http: // journals.plos.org/plosone/article?id=info%3Adoi%2F10.1371%2Fjournal.pone.0150871


The giant flightless bird Sylviornis neocaledoniae (Aves: Sylviornithidae) existed on La Grande Terre and Ile des Pins, New Caledonia, until the late Holocene when it went extinct shortly after human arrival on these islands. The species was generally considered to be a megapode (Megapodiidae) until the family Sylviornithidae was erected for it in 2005 to reflect multiple cranial autapomorphies. However, despite thousands of bones having been reported for this unique and enigmatic taxon, the postcranial anatomy has remained largely unknown. We rectify this deficiency and describe the postcranial skeleton of S. neocaledoniae based on ~600 fossils and use data from this and its cranial anatomy to make a comprehensive assessment of its phylogenetic affinities. Sylviornis neocaledoniae is found to be a stem galliform, distant from megapodiids, and the sister taxon to the extinct flightless Megavitiornis altirostris from Fiji, which we transfer to the family Sylviornithidae. These two species form the sister group to extant crown-group galliforms. Several other fossil galloanseres also included in the phylogenetic analysis reveal novel hypotheses of their relationships as follows: Dromornis planei (Dromornithidae) is recovered as a stem galliform rather than a stem anseriform; Presbyornis pervetus (Presbyornithidae) is the sister group to Anseranatidae, not to Anatidae; Vegavis iaai is a crown anseriform but remains unresolved relative to Presbyornis pervetus, Anseranatidae and Anatidae. Sylviornis neocaledoniae was reconstructed herein to be 0.8 m tall in a resting stance and weigh 27–34 kg. The postcranial anatomy of S. neocaledoniae shows no indication of the specialised adaptation to digging seen in megapodiids, with for example, its ungual morphology differing little from that of chicken Gallus gallus. These observations and its phylogenetic placement as stem galliforms makes it improbable that this species employed ectothermic incubation or was a mound-builder. Sylviornis neocaledoniae can therefore be excluded as the constructor of tumuli in New Caledonia.


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Free pdf:


Meagan M. Gilbert, Eric Snively & John Cotton (2016)

The Tarsometatarsus of the Ostrich Struthio camelus: Anatomy, Bone Densities, and Structural Mechanics. 

PLoS ONE 11(3): e0149708. 

doi:10.1371/journal.pone.0149708

http: // dx.doi.org/10.1371/journal.pone.0149708


Background


The ostrich Struthio camelus reaches the highest speeds of any extant biped, and has been an extraordinary subject for studies of soft-tissue anatomy and dynamics of locomotion. An elongate tarsometatarsus in adult ostriches contributes to their speed. The internal osteology of the tarsometatarsus, and its mechanical response to forces of running, are potentially revealing about ostrich foot function.


Methods/Principal Findings


Computed tomography (CT) reveals anatomy and bone densities in tarsometatarsi of an adult and a young juvenile ostrich. A finite element (FE) model for the adult was constructed with properties of compact and cancellous bone where these respective tissues predominate in the original specimen. The model was subjected to a quasi-static analysis under the midstance ground reaction and muscular forces of a fast run. Anatomy–Metatarsals are divided proximally and distally and unify around a single internal cavity in most adult tarsometatarsus shafts, but the juvenile retains an internal three-part division of metatarsals throughout the element. The juvenile has a sparsely ossified hypotarsus for insertion of the m. fibularis longus, as part of a proximally separate third metatarsal. Bone is denser in all regions of the adult tarsometatarsus, with cancellous bone concentrated at proximal and distal articulations, and highly dense compact bone throughout the shaft. Biomechanics–FE simulations show stress and strain are much greater at midshaft than at force applications, suggesting that shaft bending is the most important stressor of the tarsometatarsus. Contraction of digital flexors, inducing a posterior force at the TMT distal condyles, likely reduces buildup of tensile stresses in the bone by inducing compression at these locations, and counteracts bending loads. Safety factors are high for von Mises stress, consistent with faster running speeds known for ostriches.


Conclusions/Significance


High safety factors suggest that bone densities and anatomy of the ostrich tarsometatarsus confer strength for selectively critical activities, such as fleeing and kicking predators. Anatomical results and FE modeling of the ostrich tarsometatarsus are a useful baseline for testing the structure’s capabilities and constraints for locomotion, through ontogeny and the full step cycle. With this foundation, future analyses can incorporate behaviorally realistic strain rates and distal joint forces, experimental validation, and proximal elements of the ostrich hind limb.