http://blog.gmane.org/gmane.science.dinosaurs.general hourly 1 1901-01-01T00:00+00:00 http://gmane.org/img/gmane-25t.png http://gmane.org http://comments.gmane.org/gmane.science.dinosaurs.general/57227 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com A new online paper: Michael J. Polcyn, Louis L. Jacobs, Ricardo Araújo, Anne S. Schulp &amp; Octávio Mateus (2013) Physical Drivers of Mosasaur Evolution. Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication) doi: http://dx.doi.org/10.1016/j.palaeo.2013.05.018 http://www.sciencedirect.com/science/article/pii/S0031018213002514 Mosasaurs are marine squamates with a 32.5 million-year history from their appearance at 98 Ma to their extinction at the K-Pg boundary (65.5 Ma). Using a database of 43 generic and 94 species-level taxa, we compare the taxonomic diversity and patterns of morphological disparity in mosasaurs with sea level, sea surface temperature, and stable carbon isotope curves for the Upper Cretaceous to explore factors that may have influenced their evolution. No single factor unambiguously accounts for all radiations, diversification, and extinctions; however, the broader patterns of taxonomic diversification and morphological disparity point to niche differentiation in a “fishing up” scenario under the influence of “bottom-up” selective pressures. The most likely driving force in mosasaur evolution was high productivity in the Late Cretaceous, driven by tectonically controlled sea levels and climatically controlled ocean stratification and nutrient delivery. When productivity collapsed at the end of the Cretaceous, coincident with bolide impact, mosasaurs became extinct. </pre> Ben Creisler 2013-05-25T02:07:06 http://comments.gmane.org/gmane.science.dinosaurs.general/57226 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com A new advance paper: Neil Brocklehurst , Christian F. Kammerer , and Jörg Fröbisch (2013) The early evolution of synapsids, and the influence of sampling on their fossil record. Paleobiology 39(3):470-490. 2013 doi: http://dx.doi.org/10.1666/12049 http://www.bioone.org/doi/abs/10.1666/12049 Supplementary materials deposited at Dryad: doi 10.5061/dryad.cq376 Synapsids dominated the terrestrial realm between the late Pennsylvanian and the Triassic. Their early evolution includes some of the first amniotes to evolve large size, herbivory, and macro-predators. However, little research has focused on the changes in diversity occurring during this early phase in their evolutionary history, with more effort concentrating on later events such the Permo-Triassic extinction. Here we assess synapsid diversity, at both the species and genus levels, between the Carboniferous (Moscovian) and the Middle Permian (Capitanian). A raw, taxic diversity (richness) estimate is generated, and we use two separate methods to correct for sampling biases in this curve. To remove the effect of anthropogenic sampling bias, we apply a recently published modification of the residual diversity method, and then generate a supertree, using matrix representation with parsimony to infer ghost lineages and obtain a phylogenetic diversity estimate. The general diversity pattern reflects the initial diversification of synapsids in the late Pennsylvanian and early Cisuralian, which was followed by an extinction event during the Sakmarian. Diversity recovered during the Artinskian and Kungurian, coinciding with the radiation of Caseidae, although other families begin to decline. A second extinction event occurred across the Kungurian/Roadian boundary, in which Edaphosauridae and Ophiacodontidae died out although Caseidae and Therapsida diversified. The sampling-corrected curves reveal further extinction during the Roadian, although therapsids were again unaffected. Pelycosaurian-grade synapsids survived during the Wordian and Capitanian, but were a minor part of an otherwise therapsid-dominated fauna. Evidence of significant anthropogenic sampling bias calls into question previous diversity studies that have not employed sampling correction. </pre> Ben Creisler 2013-05-24T16:10:37 http://comments.gmane.org/gmane.science.dinosaurs.general/57225 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com A new online paper: Huaichun Wu, Shihong Zhang, Ganqing Jiang, Tianshui Yang, Junhua Guo &amp; Haiyan Li (2013) Astrochronology for the Early Cretaceous Jehol Biota in Northeastern China. Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication) doi: http://dx.doi.org/10.1016/j.palaeo.2013.05.017 http://www.sciencedirect.com/science/article/pii/S0031018213002502 The Early Cretaceous Jehol Biota in Northeastern China provides an evolutionary window for ‘feathered’ dinosaurs, primitive birds, insects and early flowering plants. It also provides critical information for the biodiversity changes of the Early Cretaceous terrestrial ecosystem. Here we report a time series analysis for the 11.2-m-thick, fossil-bearing lacustrine deposits at the Sihetun section in western Liaoning, Northeastern China on the basis of high-resolution magnetic susceptibility (MS) and anhysteretic remanent magnetization (ARM) measurements. A hierarchy of sedimentary cycle bands of 120-260 cm, 50-67 cm and 18-42 cm were recorded in the MS and ARM series. With available radioisotope age constraints from the same section, sedimentary cycles of 120-260 cm, 50-67 cm and 18-42 cm were interpreted as Milankovitch cycles of short eccentricity (130 and 95 kyr), obliquity (36.6 and 46 kyr), and precession (22.1, 20.9 and 18 kyr), respectively. The 100 kyr-tuned ‘floating’ astronomical time scale indicates that the duration of the 11.2-m-thick section is ~ 0.67 Myr and the average depositional rate is ~ 1.70 cm/kyr. The duration of the 1.8-m-thick, main fossil-bearing interval that contains 8 beds of ‘feathered’ dinosaur/primitive bird fossils can be estimated as short as 150 kyr. The results suggest that climate fluctuations manifested in palaeobotanical, sedimentological and geochemical records of the Yixian Formation may have been controlled by orbital forcing during Early Cretaceous. </pre> Ben Creisler 2013-05-24T02:56:41 http://comments.gmane.org/gmane.science.dinosaurs.general/57224 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com A new open-access online paper: J.R. Foster (2013) Ecological Segregation of the Late Jurassic Stegosaurian and Iguanodontian Dinosaurs of the Morrison Formation in North America: Pronounced or Subtle? PalArch’s Journal of Vertebrate Palaeontology 10(3): 1-11 ISSN 1567-2158 http://www.palarch.nl/2013/05/foster-j-r-2013-ecological-segregation-of-the-late-jurassic-stegosaurian-and-iguanodontian-dinosaurs-of-the-morrison-formation-in-north-america-pronounced-or-subtle-palarchs-jo/ Free pdf: http://www.palarch.nl/wp-content/Foster-2013.pdf The Upper Jurassic Morrison Formation of western North America has yielded a number of specimens assigned to the ornithischian dinosaurs Stegosaurus and Camptosaurus, and many of these specimens come from channel sandstone deposits. Six new specimens are recorded mostly from channel sandstones as well. Indeed, early analyses of site occurrences (reducing the effects of large single-site samples) suggested that Stegosaurus and Camptosaurus were more often found in channel sandstone deposits than other common Morrison Formation dinosaurs such as Camarasaurus or Diplodocus. This also indicated the possibility of ecological segregation of the former two genera from other herbivorous dinosaurs of the Morrison. Revisiting this question with additional data suggests the pattern may not be as strong as it once appeared. Analysis of occurrence data indicates that Stegosaurus and Camptosaurus occur in channel sandstone deposits slightly more frequently than the two sauropods, but statistical analysis of this pattern by either localities or individuals indicates little significance to the trend. However, Camptosaurus appears more strongly associated with channel sandstone deposits relative to other dinosaurs than does Stegosaurus. These results suggest that any ecological segregation of these genera was moderate, but that, if present, the segregation was more pronounced in Camptosaurus. </pre> Ben Creisler 2013-05-23T15:12:41 http://comments.gmane.org/gmane.science.dinosaurs.general/57223 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com A new online paper with a new sauropod Yunmenglong: Junchang Lü, Li Xu, Hanyong Pu, Xingliao Zhang, Yiyang Zhang, Songhai Jia, Huali Chang, Jiming Zhang &amp; Xuefang Wei (2013) A new sauropod dinosaur (Dinosauria, Sauropoda) from the late Early Cretaceous of the Ruyang Basin (central China). Cretaceous Research (advance online publication) doi: http://dx.doi.org/10.1016/j.cretres.2013.04.009 http://www.sciencedirect.com/science/article/pii/S0195667113000839 A new long-necked sauropod dinosaur, Yunmenglong ruyangensis gen. et sp. nov., is erected on the basis of an incomplete skeleton from the late Early Cretaceous Haoling Formation of the Ruyang Basin, Henan Province. The characters of the anterior cervical vertebrae, the shape of the neural canal of the dorsal vertebra and the ball-shaped distal end of the neural spine of caudal vertebrae with coarse surfaces differ from other long-necked sauropod dinosaurs. The new genus has characters in common with both Euhelopus and Erketu; it represents the first long-necked sauropod dinosaur recorded from central China to date. The rod-like, well-developed epipophyses and the pleurocoels on the cervical vertebrae indicate that it may be close to Euhelopus, an observation also confirmed by a phylogenetic analysis, which shows that Erketu, Yunmenglong and Qiaowanlong form a clade, and are more derived than Euhelopus. </pre> Ben Creisler 2013-05-23T14:46:51 http://comments.gmane.org/gmane.science.dinosaurs.general/57222 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com A new online paper: Daniel E. Barta, Krista M. Brundridge, Jasmine A. Croghan, Frankie D. Jackson, David J. Varricchio, Xingsheng Jin &amp; Ashley W. Poust (2013) Eggs and clutches of the Spheroolithidae from the Cretaceous Tiantai basin, Zhejiang Province, China. Historical Biology (advance online publication) DOI:10.1080/08912963.2013.792811 http://www.tandfonline.com/doi/full/10.1080/08912963.2013.792811#.UZ2Pf7W1FcQ Numerous discoveries in the Tiantai basin of Zhejiang Province, China, enrich our understanding of the parataxonomy, paleobiology and taphonomic histories of fossil eggs from a diverse array of Cretaceous oofamilies. We describe the most abundant of these egg types catalogued in the Zhejiang Museum of Natural History, Spheroolithus cf. zhangtoucaoensis (oofamily Spheroolithidae). Scanning electron microscopy, here utilised for the first time on Spheroolithus eggs from Tiantai, and petrographic microscopy reveal 0.81–1.37-mm thick eggshell composed of a single structural layer of calcite with slightly flaring shell units, irregular pores, horizontal accretion lines and a sweeping extinction pattern under crossed polars. This contradicts previous reports of the presence of two structural layers in Tiantai Spheroolithus. Clutches consist of 2–13 eggs arranged in an irregular, single-layered pattern. As these eggs are among the oldest Asian examples of Spheroolithus currently known, they may shed light on the early evolution of this oogenus. This study establishes the definitive presence of the Spheroolithidae in the Tiantai basin, contra recent reports, and provides the framework for ongoing examination of egg diversity and taphonomy in the Tiantai basin. </pre> Ben Creisler 2013-05-23T03:48:12 http://comments.gmane.org/gmane.science.dinosaurs.general/57221 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com A new online paper: Marcos G. Becerra, Diego Pola, Claudia A. Marsicano &amp; Oliver W.M. Rauhut (2013) The dentition of Manidens condorensis (Ornithischia; Heterodontosauridae) from the Jurassic Cañadón Asfalto Formation of Patagonia: morphology, heterodonty and the use of statistical methods for identifying isolated teeth. Historical Biology (advance online publication) DOI:10.1080/08912963.2013.794227 http://www.tandfonline.com/doi/full/10.1080/08912963.2013.794227#.UZ2Pm7W1FcQ The recently described Manidens condorensis is one of the most completely known taxa of the family Heterodontosauridae from the southern landmasses. However, some dental aspects are not well known due to preservational problems in the type material. This contribution reports new isolated teeth found in the Cañadón Asfalto Formation (Early-Middle Jurassic). These teeth are referred to Manidens condorensis based on the presence of autapomorphic characters of the unusual dentition of this taxon, such as the highly asymmetric tooth crowns and small crenulations on each denticles. The isolated crowns are well preserved and reveal the presence of undescribed and new autapomorphical features, including apical and basal wear facets on the occlusal surface of isolated crowns and a wear surface also in the caniniform tooth. We carried out statistical analyses (including morphogeometrical and discriminant analyses), using the holotype crowns as a morphological starting point, for characterising shape variation of the crowns along the toothrow and for identifying the position of isolated crowns. These analyses allow defining morphological regions within the postcaniniform toothrow and produce a metrically based discriminant function to predict the hypothetical position of future discoveries, providing a methodological framework that could be applied to other extinct heterodont dinosaurs. </pre> Ben Creisler 2013-05-23T03:46:41 http://comments.gmane.org/gmane.science.dinosaurs.general/57220 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com A number of new non-dino papers (plus a video) that may be interest: S. Sanchez &amp; R. R. Schoch (2013) Bone Histology Reveals a High Environmental and Metabolic Plasticity as a Successful Evolutionary Strategy in a Long-Lived Homeostatic Triassic Temnospondyl. Evolutionary Biology (advance online publication) DOI: 10.1007/s11692-013-9238-3 http://link.springer.com/article/10.1007/s11692-013-9238-3 NOTE: pdf is open access (for now) Evolutionary stasis (long-term stability of morphology in an evolving lineage) is a pattern for which explanations are usually elusive. The Triassic tetrapod Gerrothorax pulcherrimus, a gill-bearing temnospondyl, survived for 35 million years in the Germanic Basin of Central Europe persisting throughout the dinosaur-dominated Late Triassic period. This evolutionary stasis coincides with the occurrence of this species in a wide range of habitats and environmental conditions. By the combination of palaeoecological and palaeohistological analyses, we found great ecological flexibility in G. pulcherrimus and present substantial evidence of developmental and metabolic plasticity despite the morphological stasis. We conclude that G. pulcherrimus could show the capacity to settle in water bodies too harsh or unpredictable for most other tetrapods. This would have been made possible by a unique life history strategy that involved a wide reaction norm, permitting adjustment to fluctuating conditions such as salinity and level of nutrients. Growth rate, duration of juvenile period, age at maturity, and life span were all subject to broad variation within specimens of G. pulcherrimus in one single lake and in between different lakes. In addition to providing a better understanding of fossil ecosystems, this study shows the potential of such a methodology to encourage palaeobiologists and evolutionary biologists to consider the mechanisms of variation in extant and fossil organisms by using a similar time-scope reference. == Silvia N Césari and Carina E Colombi (2013) A new Late Triasssic phytogeographical scenario in westernmost Gondwana. Nature Communications 4, Article number: 1889 doi:10.1038/ncomms2917 http://www.nature.com/ncomms/journal/v4/n5/full/ncomms2917.html Floral provincialism within the Southern Hemisphere during the Late Triassic (230 Ma) is characterized by the Ipswich and Onslow provinces, recognized originally in eastern Gondwana. However, new palynological assemblages from the Ischigualasto Formation, northwestern Argentina (231–225 Ma), change the phytogeographic interpretation for the Carnian–Norian in the westernmost Gondwana, which was previously considered part of the southern floral Ipswich province. Here we show the presence of diagnostic Euramerican species within assemblages dominated by Gondwanan taxa that allows us to refer the palynofloras to the Onslow province. Our new data extend the Onslow floral belt, previously recognized from the western edge of Tethys to Timor, to the western margin of South America. This has implications for palaeophytogeography, palaeoclimate reconstructions and the palaeoecology of a Triassic ecosystem, which has yielded significant vertebrate remains and is regarded important in the early evolution of groups such as the Dinosauria. === Mammals across K/Pg boundary in Montana (video talk) Greg Wilson's talk Mammals Inherit the Earth at Royal Tyrrell Museum is about mammals across the K/Pg boundary and the mass extinction. http://www.youtube.com/watch?v=8lFHHRqhS8k&amp;list=UUFYePvzFqxxk1xTD3hMmogw&amp;index=1 == Adatte, Karl Föllmi, Izabella Ploch &amp; Jörg Mutterlose (2013) Reconstructing Valanginian (Early Cretaceous) mid-latitude vegetation and climate dynamics based on spore-pollen assemblages. Review of Palaeobotany and Palynology (advance online publication) doi: http://dx.doi.org/10.1016/j.revpalbo.2013.05.003 http://www.sciencedirect.com/science/article/pii/S0034666713000912 Changes in terrestrial vegetation patterns during the Valanginian (Early Cretaceous) and their link to major climatic and environmental alterations are poorly studied. In this study, the spatial and temporal changes in plant community structure are reconstructed based on spore-pollen records from two mid-latitude sites located in the Mid-Polish Trough (MPT, central Poland), and the Vocontian Basin (VB, southeast France). Stratigraphic control is provided by δ13Ccarb chemostratigraphy and calcareous nannofossil biostratigraphy. Reconstruction of hinterland vegetation is based on palynological investigations of 83 samples from hemipelagic (VB) and marginal marine (MPT) sediments rich in terrestrial palynomorphs. A total of 45 palynomorph taxa were identified at generic level (30 spores, 15 pollen). Vegetation around the MPT was dominated by araucarian/cupressacean conifers while that surrounding the VB was dominated by drought-resistant cheirolepidiacean conifers. At both sites the understorey and/or vegetation of open areas was dominated by pteridophytes. An early Valanginian gradual trend towards humid conditions at the MPT, well expressed by a distinct increase in the spore-pollen ratio, culminates in a short-lived spore-maximum stratigraphically located at the lower/upper Valanginian boundary. It is characterized by low conifer abundances and high abundances of the fern spore taxa Cyathidites, Leiotriletes and Gleicheniidites accompanied by enhanced abundances of the pteridosperm pollen Vitreisporites pallidus, whose parent plants are assumed to be indicative of swamp habitats. The spore-maximum is coeval to a similar peak observed in the VB, characterized by essentially the same taxa. Here, the spore-maximum is preceded by a protracted phase of arid conditions, characterized by low spore abundances and exceptionally high numbers of the cheirolepidiacean conifer pollen Classopollis. Changes in moisture, identified as the key climatic factor determining trends and turnovers in vegetation, were probably controlled by a monsoonal circulation. The supra-regional humid phase expressed by the coeval spore maxima was probably induced by an intensified monsoonal climate. The temporal influence of a northern hemisphere arid belt at the VB, under the influence of the subtropical high-pressure belt, may have caused the temporal drying not affecting the MPT site, located further north. == Miocene crocodylian diversity in South America T. M. Scheyer, O. A. Aguilera, M. Delfino, D. C. Fortier, A. A. Carlini, R. Sánchez, J. D. Carrillo-Briceño, L. Quiroz, and M. R. Sánchez-Villagra. Crocodylian diversity peak and extinction in the late Cenozoic of the northern Neotropics. Nature Communications 4, Article number: 1907 doi:10.1038/ncomms2940 http://www.nature.com/ncomms/journal/v4/n5/full/ncomms2940.html Northern South America and South East Asia are today’s hotspots of crocodylian diversity with up to six (mainly alligatorid) and four (mainly crocodylid) living species respectively, of which usually no more than two or three occur sympatrically. In contrast, during the late Miocene, 14 species existed in South America. Here we show a diversity peak in sympatric occurrence of at least seven species, based on detailed stratigraphic sequence sampling and correlation, involving four geological formations from the middle Miocene to the Pliocene, and on the discovery of two new species and a new occurrence. This degree of crocodylian sympatry is unique in the world and shows that at least several members of Alligatoroidea and Gavialoidea coexisted. By the Pliocene, all these species became extinct, and their extinction was probably related to hydrographic changes linked to the Andean uplift. The extant fauna is first recorded with the oldest Crocodylus species from South America. </pre> Ben Creisler 2013-05-22T15:57:52 http://comments.gmane.org/gmane.science.dinosaurs.general/57219 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com A new online paper: Bradley McFeeters, Michael J. Ryan, Sanja Hinic-Frlog &amp; Claudia Schröder-Adams (2013) A reevaluation of Sigilmassasaurus brevicollis (Dinosauria) from the Cretaceous of Morocco. Canadian Journal of Earth Sciences (advance online publication) doi: 10.1139/cjes-2012-0129 http://www.nrcresearchpress.com/doi/abs/10.1139/cjes-2012-0129#.UZwdrrW1FcQ The original hypodigm of the controversial mid-Cretaceous Moroccan dinosaur Sigilmassasaurus brevicollis is redescribed, and the diagnosis of the taxon is revised. Unambiguously referred material is restricted to cervical and anterior dorsal vertebrae sharing apomorphies with the holotype. A newly recognized diagnostic character of Sigilmassasaurus is the absence of anterior and posterior interzygapophyseal laminae of the neural arch, so that the neural spine directly meets the dorsal margin of the neural canal. A phylogenetic analysis supports the inclusion of Sigilmassasaurus in Tetanurae but not in Carcharodontosauridae. Sigilmassasaurus is distinct from all other theropods known from comparable material and is thus retained as a valid taxon. </pre> Ben Creisler 2013-05-22T01:26:30 http://comments.gmane.org/gmane.science.dinosaurs.general/57217 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com New in open-access Palaeontologia Electronica: Eric Snively, John R. Cotton, Ryan Ridgely, and Lawrence M. Witmer (2013) Multibody dynamics model of head and neck function in Allosaurus (Dinosauria, Theropoda). Palaeontologia Electronica Vol. 16, Issue 2; 11A 29p palaeo-electronica.org/content/2013/389-allosaurus-feeding http://palaeo-electronica.org/content/2013/389-allosaurus-feeding We present a multibody dynamics model of the feeding apparatus of the large Jurassic theropod dinosaur Allosaurus that enables testing of hypotheses about the animal's feeding behavior and about how anatomical parameters influence function. We created CT- and anatomical-inference-based models of bone, soft tissue, and air spaces which we use to provide inertial properties for musculoskeletal dynamics. Estimates of bone density have a surprisingly large effect on head inertial properties, and trachea diameter strongly affects moments of inertia of neck segments for dorsoventral movements. The ventrally-placed insertion of m. longissimus capitis superficialis in Allosaurus imparted over twice the ventroflexive accelerations of a proxy control insertion lateral to the occipital condyle, the latter being its position in nearly all other theropods. A feeding style that involved defleshing a carcass by avian-raptor-like retraction of the head in Allosaurus is more probable than is lateroflexive shake-feeding, such as that seen in crocodilians and inferred for tyrannosaurids. </pre> Ben Creisler 2013-05-21T18:46:14 http://comments.gmane.org/gmane.science.dinosaurs.general/57215 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com A new online article: S. Lautenschlager &amp; T. Hübner (2013) Ontogenetic trajectories in the ornithischian endocranium. Journal of Evolutionary Biology (advance online publication) DOI: 10.1111/jeb.12181 http://onlinelibrary.wiley.com/doi/10.1111/jeb.12181/abstract Understanding ontogenetic and developmental patterns is critical for reconstructing the life history of fossil vertebrates. In dinosaurs, ontogenetic studies have nearly exclusively focused on changes in the cranial and post-cranial skeleton, whereas ontogenetic changes in the endocranium have received little attention. Here, we present digital reconstructions of the brain and inner ear anatomy of two ontogenetic stages of the Jurassic ornithischian dinosaur Dysalotosaurus lettowvorbecki. Results show that the endocranial anatomy underwent considerable changes during growth, including a rostrocaudal elongation of the olfactory apparatus, a reduction in the cephalic and pontine flexure and an increase in cerebellum size. Functional elements, such as the cerebral hemispheres and the inner ear, were already well developed in early ontogenetic stages, indicating a large degree of precociality. The anisotropic pattern of size and shape changes in the endocranium further indicates that ontogenetic trajectories may be controlled by functional and environmental demands in the different growth stages in Dysalotosaurus lettowvorbecki. The occurrence of similar ontogenetic patterns in the endocranial anatomy of derived ornithopod dinosaurs suggests a more widespread distribution of this growth trajectory. === See also: http://phys.org/news/2013-05-fossil-brain-teaser-reveals-patterns.html </pre> Ben Creisler 2013-05-20T21:32:18 http://comments.gmane.org/gmane.science.dinosaurs.general/57214 <pre>David B. Baier. Stephen M. Gatesy, Kenneth P. Dial (2013) Three-Dimensional, High-Resolution Skeletal Kinematics of the Avian Wing and Shoulder during Ascending Flapping Flight and Uphill Flap-Running. PLOS ONE 8: e63982 Abstract: "Past studies have shown that birds use their wings not only for flight, but also when ascending steep inclines. Uphill flaprunning or wing-assisted incline running (WAIR) is used by both flight-incapable fledglings and flight-capable adults to retreat to an elevated refuge. Despite the broadly varying direction of travel during WAIR, level, and descending flight, recent studies have found that the basic wing path remains relatively invariant with reference to gravity. If so, joints undergo disparate motions to maintain a consistent wing path during those specific flapping modes. The underlying skeletal motions, however, are masked by feathers and skin. To improve our understanding of the form-functional relationship of the skeletal apparatus and joint morphology with a corresponding locomotor behavior, we used XROMM (Xray Reconstruction of Moving Morphology) to quantify 3-D skeletal kinematics in chukars (_Alectoris chukar_) during WAIR (ascending with legs and wings) and ascending flight (AF, ascending with wings only) along comparable trajectories. Evidence here from the wing joints demonstrates that the glenohumeral joint controls the vast majority of wing movements. More distal joints are primarily involved in modifying wing shape. All bones are in relatively similar orientations at the top of upstroke during both behaviors, but then diverge through downstroke. Total excursion of the wing is much smaller during WAIR and the tip of the manus follows a more vertical path. The WAIR stroke appears ‘‘truncated’’ relative to ascending flight, primarily stemming from ca. 50% reduction in humeral depression. Additionally, the elbow and wrist exhibit reduced ranges of angular excursions during WAIR. The glenohumeral joint moves in a pattern congruent with being constrained by the acrocoracohumeral ligament. Finally, we found pronounced lateral bending of the furcula during the wingbeat cycle during ascending flight only, though the phasic pattern in chukars is opposite of that observed in starlings (_Sturnus vulgaris_)." Because it's a PLoS One paper, the main text is highly explanatory, and the paper is replete with great figures. These PLoS papers are a joy to read. One revelation is that uphill flap-running or WAIR (wing-assisted incline running) requires extensive motion at the glenohumeral joint, comparable to ascending flight. Although not directly addressed in this particular study, WAIR has been proposed as an incipient flight behavior in the ancestors of birds; this hypothesis has been advanced in a number of publications (including in some especially high-impact journals). However, given the limited range of humeral elevation inferred for non-avian maniraptorans and early birds, I very much doubt that they were capable of WAIR. If, as some people have suggested, early flying theropods had a deltoideus-driven upstroke (to compensate for limited humeral elevation), this would seem to be incompatible with WAIR - and controlled flapping descent (CFD) too. Although WAIR is a fascinating behavior exhibited by some modern avians, there doesn't seem to be much to recommend it as an incipient flight behavior in the evolution of flapping flight. This conundrum has been raised before. WAIR is an "advanced" flight behavior, even if it can be executed using incipient wings (such as present in juvenile chukars). Cheers Tim </pre> Tim Williams 2013-05-20T03:58:08 http://comments.gmane.org/gmane.science.dinosaurs.general/57213 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com A new online paper: Yanina Herrera, Marta S. Fernández &amp; Zulma Gasparini (2013) Postcranial skeleton of Cricosaurus araucanensis (Crocodyliformes: Thalattosuchia): morphology and palaeobiological insights. Alcheringa 37 (advance online publication) 1–14 DOI: 10.1080/03115518.2013.743709 http://www.tandfonline.com/doi/full/10.1080/03115518.2013.743709#.UZkLobW1FcQ The metriorhynchid crocodyliform Cricosaurus araucanensis (Gasparini &amp; Dellapé) has been documented from Tithonian (Upper Jurassic) strata of the Vaca Muerta Formation exposed in the Neuquén Basin, northwest Patagonia, Argentina. Postcranial components of this species were mentioned but not described in the original analysis. Subsequently, other authors described the forelimbs. The postcranial elements of metriorhynchids are poorly documented in comparison with their skulls, but new data from C. araucanensis reveal delayed ossification of the caudal neurocentral sutures indicating skeletal paedomorphosis affecting not only the appendicular skeleton but also the posterior region of the vertebral column. The morphology of the caudal region (transverse processes of the first caudal vertebrae ventrally deflected) and the reduction in the femur of the fourth trochanter suggest a reduction of the hypaxial musculature allowing increased epaxial musculature. This pattern of musculoskeletal arrangement is consistent with the swimming style and propulsion by lateral undulation of the tail, as proposed by previous authors. </pre> Ben Creisler 2013-05-19T17:34:36 http://comments.gmane.org/gmane.science.dinosaurs.general/57212 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com A new online paper: P. Martin Sander, Nicole Klein, Paul C. H. Albers, Constanze Bickelmann &amp; Herman Winkelhorst (2013) Postcranial morphology of a basal Pistosauroidea (Sauropterygia) from the Lower Muschelkalk of Winterswijk, The Netherlands. Paläontologische Zeitschrift (advance online publication) DOI: 10.1007/s12542-013-0181-5 http://link.springer.com/article/10.1007/s12542-013-0181-5 Two partial postcranial skeletons from the Lower Muschelkalk (early Anisian) of Winterswijk, The Netherlands, are described in detail. The specimens were assigned to basal Pistosauroidea, presumably to cf. Cymatosaurus or a closely related taxon. Cymatosaurus is currently the earliest member of the Pistosauroidea and is only known from skull material. Taxonomical assignment is based on humerus morphology and histology, and on morphological differences from other Sauropterygia (Nothosauria and Pachypleurosauria). </pre> Ben Creisler 2013-05-19T02:32:06 http://comments.gmane.org/gmane.science.dinosaurs.general/57211 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com A new online paper: Marta S. Fernández and Marianella Talevi (2013) Ophthalmosaurian (Ichthyosauria) records from the Aalenian–Bajocian of Patagonia (Argentina): an overview. Geological Magazine (advance online publication) DOI: http://dx.doi.org/10.1017/S0016756813000058 http://128.232.233.5/action/displayAbstract?fromPage=online&amp;aid=8920772&amp;fulltextType=RA&amp;fileId=S0016756813000058 The oldest ophthalmosaurian records worldwide have been recovered from the Aalenian–Bajocian boundary of the Neuquén Basin in Central-West Argentina (Mendoza and Neuquén provinces). Although scarce, they document a poorly known period in the evolutionary history of parvipelvian ichthyosaurs. In this contribution we present updated information on these fossils, including a phylogenetic analysis, and a redescription of ‘Stenopterygius grandis’ Cabrera, 1939. Patagonian ichthyosaur occurrences indicate that during the Bajocian the Neuquén Basin palaeogulf, on the southern margins of the Palaeopacific Ocean, was inhabited by at least three morphologically discrete taxa: the slender Stenopterygius cayi, robust ophthalmosaurian Mollesaurus periallus and another indeterminate ichthyosaurian. Rib bone tissue structure indicates that rib cages of Bajocian ichthyosaurs included forms with dense rib microstructure (Mollesaurus) and forms with an ‘osteoporotic-like’ pattern (Stenopterygius cayi). </pre> Ben Creisler 2013-05-17T15:15:58 http://comments.gmane.org/gmane.science.dinosaurs.general/57210 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com A new online paper: Chun Li, Da-Yong Jiang, Long Cheng, Xiao-Chun Wu and Olivier Rieppel (2013) A new species of Largocephalosaurus (Diapsida: Saurosphargidae), with implications for the morphological diversity and phylogeny of the group. Geological Magazine (advance online publication) DOI: http://dx.doi.org/10.1017/S001675681300023X http://128.232.233.5/action/displayAbstract?fromPage=online&amp;aid=8920775&amp;fulltextType=RA&amp;fileId=S001675681300023X Largocephalosaurus polycarpon Cheng et al. 2012 was erected after the study of the skull and some parts of a skeleton and considered to be an eosauropterygian. Here we describe a new species of the genus, Largocephalosaurus qianensis, based on three specimens. The new species provides many anatomical details which were described only briefly or not at all in the type species, and clearly indicates that Largocephalosaurus is a saurosphargid. It differs from the type species mainly in having three premaxillary teeth, a very short retroarticular process, a large pineal foramen, two sacral vertebrae, and elongated small granular osteoderms mixed with some large ones along the lateral most side of the body. With additional information from the new species, we revise the diagnosis and the phylogenetic relationships of Largocephalosaurus and clarify a set of diagnostic features for the Saurosphargidae Li et al. 2011. Largocephalosaurus is characterized primarily by an oval supratemporal fenestra, an elongate dorsal ‘rib-basket’, a narrow and elongate transverse process of the dorsal vertebrae, and the lack of a complete dorsal carapace of osteoderms. The Saurosphargidae is distinct mainly in having a retracted external naris, a jugal–squamosal contact, a large supratemporal extensively contacting the quadrate shaft, a leaf-like tooth crown with convex labial surface and concave lingual surface, a closed dorsal ‘rib-basket’, many dorsal osteoderms, a large boomerang-like or atypical T-shaped interclavicle. Current evidence suggests that the Saurosphargidae is the sister-group of the Sauropterygia and that Largocephalosaurus is the sister-group of the Saurosphargis–Sinosaurosphargis clade within the family. </pre> Ben Creisler 2013-05-17T15:14:23 http://comments.gmane.org/gmane.science.dinosaurs.general/57204 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com New in PLoS ONE: Michael Pittman, Stephen M. Gatesy, Paul Upchurch, Anjali Goswami &amp; John R. Hutchinson (2013) Shake a Tail Feather: The Evolution of the Theropod Tail into a Stiff Aerodynamic Surface. PLoS ONE 8(5): e63115. doi:10.1371/journal.pone.0063115 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0063115 Theropod dinosaurs show striking morphological and functional tail variation; e.g., a long, robust, basal theropod tail used for counterbalance, or a short, modern avian tail used as an aerodynamic surface. We used a quantitative morphological and functional analysis to reconstruct intervertebral joint stiffness in the tail along the theropod lineage to extant birds. This provides new details of the tail’s morphological transformation, and for the first time quantitatively evaluates its biomechanical consequences. We observe that both dorsoventral and lateral joint stiffness decreased along the non-avian theropod lineage (between nodes Theropoda and Paraves). Our results show how the tail structure of non-avian theropods was mechanically appropriate for holding itself up against gravity and maintaining passive balance. However, as dorsoventral and lateral joint stiffness decreased, the tail may have become more effective for dynamically maintaining balance. This supports our hypothesis of a reduction of dorsoventral and lateral joint stiffness in shorter tails. Along the avian theropod lineage (Avialae to crown group birds), dorsoventral and lateral joint stiffness increased overall, which appears to contradict our null expectation. We infer that this departure in joint stiffness is specific to the tail’s aerodynamic role and the functional constraints imposed by it. Increased dorsoventral and lateral joint stiffness may have facilitated a gradually improved capacity to lift, depress, and swing the tail. The associated morphological changes should have resulted in a tail capable of producing larger muscular forces to utilise larger lift forces in flight. Improved joint mobility in neornithine birds potentially permitted an increase in the range of lift force vector orientations, which might have improved flight proficiency and manoeuvrability. The tail morphology of modern birds with tail fanning capabilities originated in early ornithuromorph birds. Hence, these capabilities should have been present in the early Cretaceous, with incipient tail-fanning capacity in the earliest pygostylian birds. </pre> Ben Creisler 2013-05-15T21:34:59 http://comments.gmane.org/gmane.science.dinosaurs.general/57203 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com New in PLoS ONE: Phil R. Bell &amp; Rodolfo A. Coria (2013) Palaeopathological Survey of a Population of Mapusaurus (Theropoda: Carcharodontosauridae) from the Late Cretaceous Huincul Formation, Argentina. PLoS ONE 8(5): e63409. doi:10.1371/journal.pone.0063409 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0063409 Paleoepidemiology (the study of disease and trauma in prehistoric populations) provides insight into the distribution of disease and can have implications for interpreting behavior in extinct organisms. A monospecific bonebed of the giant carcharodontosaurid Mapusaurus (minimum number of individuals = 9) from the Cañadón del Gato site, Neuquén Province, Argentina (Cenomanian) provides a rare opportunity to investigate disease within a single population of this important apex predator. Visual inspection of 176 skeletal elements belonging to a minimum of nine individuals yielded a small number of abnormalities on a cervical vertebra, two ribs, pedal phalanx, and an ilium. These are attributed to traumatic (two cases), infectious (two cases) and anomalous (one case) conditions in a minimum of one individual. The emerging picture for large theropod (abelisaurids, allosaurids, carcharodontosaurids, tyrannosaurids) populations suggests that 1) osseous abnormalities were relatively rare (7–19% of individuals) but consistently present, and 2) trauma was a leading factor in the frequency of pathological occurrences, evidence of an active, often perilous lifestyle. </pre> Ben Creisler 2013-05-15T21:31:07 http://comments.gmane.org/gmane.science.dinosaurs.general/57202 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com New in open-access PLoS ONE: Lucio M. Ibiricu, Rubén D. Martínez, Gabriel A. Casal &amp; Ignacio A. Cerda (2013) The Behavioral Implications of a Multi-Individual Bonebed of a Small Theropod Dinosaur. PLoS ONE 8(5): e64253 doi:10.1371/journal.pone.0064253 http://www.plosone.org/article/info:doi/10.1371/journal.pone.0064253 Background Central Patagonia, Argentina, preserves an abundant and rich fossil record. Among vertebrate fossils from the Upper Cretaceous Bajo Barreal Formation of Patagonia, five individuals of the small, non-avian theropod dinosaur Aniksosaurus darwini were recovered. Group behavior is an important aspect of dinosaur paleoecology, but it is not well-documented and is poorly understood among non-avian Theropoda. Methods/Principal Findings The taphonomic association of individuals from the Bajo Barreal Formation and aspects of their bone histology suggest gregarious behavior for Aniksosaurus, during at least a portion of the life history of this species. Histology indicates that the specimens were juvenile to sub-adult individuals. In addition, morphological differences between individuals, particularly proportions of the appendicular bones, are probably related to body-size dimorphism rather than ontogenetic stage. Conclusions/Significance Gregarious behaviour may have conferred a selective advantage on Aniksosaurus individuals, contributing to their successful exploitation of the Cretaceous paleoenvironment preserved in the Bajo Barreal Formation. The monospecific assemblage of Aniksosaurus specimens constitutes only the second body fossil association of small, coelurosaurian theropods in South America and adds valuable information about the paleoecologies of non-avian theropod dinosaurs, particularly in the early Late Cretaceous of Patagonia. </pre> Ben Creisler 2013-05-15T21:26:07 http://comments.gmane.org/gmane.science.dinosaurs.general/57195 <pre>Hi, I am hoping that I could get sense of what the consensus, if any, is on endothemry. I try to stay up to date and knowledgeable on all things dino-related, but I just want to be clear on this to help settle a discussion on the Ars Technica forums. I believe that it pretty solidly accepted for therapods, but maybe somewhat less so for the rest? Or am I all wrong? Thanks very much, Kelly Clowers </pre> Kelly Clowers 2013-05-15T16:34:01 http://comments.gmane.org/gmane.science.dinosaurs.general/57194 <pre>From: Ben Creisler bcreisler&lt; at &gt;gmail.com A new online open-access paper: Qi Zhao, Michael J. Benton, Xing Xu, and Martin J. Sander (2013) Juvenile-only clusters and behaviour of the Early Cretaceous dinosaur Psittacosaurus. Acta Palaeontologica Polonica (in press) doi: http://dx.doi.org/10.4202/app.2012.0128 http://app.pan.pl/article/item/app20120128.html It has hitherto been hard to prove that any association of juvenile dinosaurs represents original behaviour rather than sedimentary accumulation, and it has been hard also to determine the ages of such juveniles. A previously described specimen, which consists of an ‘adult’ Psittacosaurus with 34 fully articulated juveniles, turns out to be a composite: the ‘adult’ skull has been added, and in any case it is below breeding age. Other juvenile-only clusters have been reported, but the best examples that likely reflect behaviour rather than sedimentary accumulation are specimens from the Early Cretaceous Lujiatun beds in NE China, which were entombed beneath pyroclastic flow deposits. A remarkable juvenile-only cluster of Psittacosaurus shows clear evidence of different ages (five 2-year olds and one 3-year old) based on bone histological analysis. These juveniles may have associated together as a close knit, mixed-age herd either for protection, to enhance their foraging, or as putative helpers at the parental nest. </pre> Ben Creisler 2013-05-15T15:31:48 Search the mailing list at Gmane query http://search.gmane.org/?group=$group=gmane.science.dinosaurs.general