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Re: Iguanas breathe more like birds + Morrison Jurassic climate + other papers

Ben Creisler

Nice Ed Yong explainer blog about unidirectional respiration in
iguanas, birds, alligators...


On Mon, Nov 17, 2014 at 1:38 PM, Ben Creisler <bcreisler@gmail.com> wrote:
> Ben Creisler
> bcreisler@gmail.com
> A number of non-dino papers that may be of interest:
> Robert L. Cieri, Brent A. Craven, Emma R. Schachner, and C. G. Farmer (2014)
> New insight into the evolution of the vertebrate respiratory system
> and the discovery of unidirectional airflow in iguana lungs.
> Proceedings of the National Academy of Sciences (advance online publication)
> doi:10.1073/pnas.1405088111
> http://www.pnas.org/content/early/2014/11/13/1405088111.abstract?sid=fd212b01-b03a-4689-8006-b306560559c0
> Significance
> The avian respiratory system appears strikingly distinct from all
> other animals. Purported key innovations underpinning avian patterns
> of airflow are an enclosed intrapulmonary bronchus, intercameral
> perforations, heterogeneous parenchyma; these traits allegedly
> coevolved with separation of the cardiac ventricle into right and left
> sides and are presumed to have been favored by selection because they
> facilitate high activity metabolisms. In contradistinction to these
> prevailing theories, here we show that unidirectional flow is present
> in the lungs of the green iguana, an ectothermic animal with low
> aerobic capacity, no intrapulmonary bronchus, and no intercameral
> perforations. This discovery indicates a transformation in our
> understanding of the evolution of the vertebrate respiratory system is
> needed.
> Abstract
> The generally accepted framework for the evolution of a key feature of
> the avian respiratory system, unidirectional airflow, is that it is an
> adaptation for efficiency of gas exchange and expanded aerobic
> capacities, and therefore it has historically been viewed as important
> to the ability of birds to fly and to maintain an endothermic
> metabolism. This pattern of flow has been presumed to arise from
> specific features of the respiratory system, such as an enclosed
> intrapulmonary bronchus and parabronchi. Here we show unidirectional
> airflow in the green iguana, a lizard with a strikingly different
> natural history from that of birds and lacking these anatomical
> features. This discovery indicates a paradigm shift is needed. The
> selective drivers of the trait, its date of origin, and the
> fundamental aerodynamic mechanisms by which unidirectional flow arises
> must be reassessed to be congruent with the natural history of this
> lineage. Unidirectional flow may serve functions other than expanded
> aerobic capacity; it may have been present in the ancestral diapsid;
> and it can occur in structurally simple lungs.
> ***
> News stories:
> http://phys.org/news/2014-11-iguanas-evolved-one-way-lungs-surprisingly.html
> http://unews.utah.edu/news_releases/why-lizards-have-bird-breath/
> ===
> SMU blog about Morrison Formation climate:
> http://blog.smu.edu/research/2014/11/17/jurassic-climate-of-large-swath-of-western-u-s-was-more-complex-than-previously-known/
> The paper posted online last March:
> Timothy S. Myers, Neil J. Tabor and Nicholas A. Rosenau (2014)
> Multiproxy approach reveals evidence of highly variable
> paleoprecipitation in the Upper Jurassic Morrison Formation (western
> United States).
> GSA Bulletin (advance online publication)
> doi: 10.1130/B30941.1
> http://gsabulletin.gsapubs.org/content/early/2014/03/19/B30941.1.abstract
> Elemental analyses of paleosol B horizons in the Upper Jurassic
> Morrison Formation of the western United States provide estimates of
> mean annual precipitation (MAP) and allow determination of humidity
> regimes. Samples were collected from the lower Morrison Formation in
> New Mexico and the upper Morrison Formation in Wyoming and Montana.
> The chemical index of alteration minus potassium (CIA – K) and the
> calcium and magnesium weathering index (CALMAG) were used to estimate
> paleorainfall. CIA – K values calculated for paleosols without
> shrink-swell (vertic) features correspond to MAP estimates between 800
> and 1100 mm yr–1, with an average of 1000 mm yr–1. CALMAG values,
> calculated for vertic paleosols, correspond to MAP estimates between
> 50 and 1200 mm yr–1, with an average of 700 mm yr–1. MAP estimates
> from the older New Mexico strata indicate that early Morrison
> environments were relatively arid. MAP estimates from the younger
> Wyoming and Montana deposits reflect wetter conditions in the
> northernmost part of the Morrison Formation, but the transition from
> arid interior environments was abrupt. Humidity provinces inferred
> from geochemical proxy-based estimates of evapotranspiration and
> energy influx from precipitation range from semiarid to superhumid,
> suggesting wetter conditions than the MAP estimates, but supporting
> the relative differences in moisture among the three study areas.
> Paleoprecipitation patterns within the Morrison depositional basin do
> not match the modern latitudinal distribution of rainfall that arises
> from zonal atmospheric circulation. Comparison with the Upper Jurassic
> Lourinhã Formation in Portugal and the Vega Formation in Spain reveals
> that MAP in Late Jurassic Portuguese environments was similar to that
> in the wet northern part of the Morrison Formation, although more arid
> conditions prevailed in some areas of Portugal. Inferred humidity
> regimes for the Lourinhã Formation, which range from semiarid to
> superhumid, also indicate small-scale geographic variability in
> climate, although less pronounced than that observed in the Morrison
> Formation. Paleoenvironments in northern Spain were similar to the
> drier Morrison environments in the continental interior. Given the
> abrupt climatic transitions inferred here for the Morrison Formation,
> paleoprecipitation estimates derived from a geographically restricted
> sample may reflect only local conditions and should not necessarily be
> extrapolated to larger areas.
> ==
> Giant Miocene caiman Mourasuchus
> David Eric Tineo, Paula Bona, Leandro Martín Pérez, Gustavo Dardo
> Vergani, Gloria González, Daniel Gustavo Poiré, Zulma Gasparini &
> Pablo Legarreta (2014)
> Palaeoenvironmental implications of the giant crocodylian Mourasuchus
> (Alligatoridae, Caimaninae) in the Yecua Formation (late Miocene) of
> Bolivia.
> Alcheringa (advance online publication)
> DOI:10.1080/03115518.2015.967162
> http://www.tandfonline.com/doi/full/10.1080/03115518.2015.967162#.VGeMrfnF_To
> Outcrops of the Yecua Formation (late Miocene) are exposed for
> approximately 230 m along the La Angostura section of the Piraí River
> (50 km southwest of Santa Cruz de la Sierra). These reveal massive
> (argillic palaeosols) and laminated (quiet-water lacustrine and marsh
> settings) mudstones interbedded with thin sandstones containing
> microfossils, molluscs and vertebrate remains. Significantly, the
> succession hosts a giant crocodylian, Mourasuchus (Alligatoridae,
> Caimaninae), which is represented by both skull and postcranial
> fragments found in association with freshwater turtles and fishes.
> Mourasuchus was distributed widely from the middle Miocene of Colombia
> to upper Miocene of Venezuela, Brazil and Argentina, suggesting
> connections between major fluvial systems and an active mechanism for
> dispersal of South American freshwater vertebrates during the Miocene.
> ===
> Mongolian Cretaceous trees
> Gongle Shi, Andrew B. Leslie, Patrick S. Herendeen, Niiden Ichinnorov,
> Masamichi Takahashi, Patrick Knopf, and  Peter R. Crane (2014)
> Whole-Plant Reconstruction and Phylogenetic Relationships of Elatides
> zhoui sp. nov. (Cupressaceae) from the Early Cretaceous of Mongolia.
> International Journal of Plant Sciences 175(8): 911-930
> doi : http://www.jstor.org/stable/10.1086/677651
> http://www.jstor.org/discover/10.1086/677651?uid=3739960&uid=2134&uid=2&uid=70&uid=4&uid=3739256&sid=21105202394073
> Premise of research. Exceptionally well-preserved lignified fossils
> from the Early Cretaceous of Mongolia include abundant conifer leafy
> shoots with attached pollen cones and seed cones. A whole-plant
> reconstruction based on these fossils enables a critical evaluation of
> the relationship of this extinct plant with extant conifers.
> Methodology. Bulk lignite samples collected from the Tugrug lignite
> mine were disaggregated in water, cleaned with hydrochloric and
> hydrofluoric acids, washed, and dried in air. Fossils were then
> examined using light and scanning electron microscopy. Pivotal
> results. Elatides zhoui sp. nov. has helically arranged leaves with
> two narrow lateral stomatal bands, predominantly on the adaxial leaf
> surface. Pollen cones are usually borne laterally on shoots in tight
> spirals; each microsporophyll bears three pollen sacs that produce
> nonsaccate pollen with a small circular aperture. Seed cones have
> numerous bract-scale complexes, each with a small membranous
> ovuliferous scale and four to six seeds. Elatides zhoui is the most
> completely understood of all described Elatides species, and major
> features of seed cone and pollen cone morphology indicate that it is
> most closely related to extant Cunninghamia, which today has two
> species restricted to East Asia. Morphological cladistic analyses
> using parsimony resolved an expanded Cunninghamioideae clade, which
> includes extant Cunninghamia, E. zhoui, and other Cunninghamia-like
> fossils, as the sister group to all other extant Cupressaceae sensu
> lato.
> Conclusions. Elatides zhoui provides further evidence for the
> diversity of Cupressaceae sensu lato during the Cretaceous and
> supports the hypothesis that cunninghamioid conifers in particular
> were diverse and widespread during the early evolution of the
> Cupressaceae.
> ==