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Should end of Jurassic be 140 Ma? and other non-dino papers and news

From: Ben Creisler

A number of recent non-dino paper and some news stories that may be of interest:

Verónica V. Vennari, Marina Lescano, Maximiliano Naipauer, Beatriz
Aguirre-Urreta, Andrea Concheyro, Urs Schaltegger, Richard Armstrong,
Marcio Pimentel & Victor A. Ramos (2014)
New constraints on the Jurassic–Cretaceous boundary in the High Andes
using high-precision U–Pb data.
Gondwana Research 26(1): 374–385
DOI: 10.1016/j.gr.2013.07.005

Ammonite and nannofossil zonation of the J-K boundary in the Andean
Neuquén Basin.
SHRIMP and CA-ID-TIMS U-Pb ash-fall tuff dating in zircons in the J-K boundary.
First robust numerical age of the J-K boundary in the Andes of Western Gondwana.
LAM-MC-ICP-MS U-Pb detrital zircon ages of Kimmeridgian continental deposits.

The Jurassic–Cretaceous (J–K) boundary is poorly constrained, and is
the only Phanerozoic system boundary that lacks an internationally
accepted reference stratigraphic section (GSSP). Precise
radio-isotopic U–Pb data are unavailable for the earliest stage of the
Cretaceous— the Berriasian. The age of the Jurassic–Cretaceous
boundary was based on several assumptions, including the relative
duration of ammonite zones, the constant spreading rates of magnetic
anomalies, and the extrapolation of Rb–Sr or K–Ar isotopic data. This
paper discusses a site in an Andean Basin of Western Gondwana showing
the J–K boundary interval with geographically widespread nannofossil
markers which are here uniquely combined with precise radiometric
dates. The recent finding of a sequence of marine black shales in the
High Andes of Argentina, interbedded with ash-fall tuffs, provides
important constraints on this boundary. This succession bears
calcareous nannofossils and ammonites, which allow correlation with
well-established Tethyan floras and faunas in the northern hemisphere.
The Tithonian–Berriasian transition in the Andes was recognized on the
basis of ammonite zones and nannofossil bioevents for the first time
in the southern hemisphere. The new ages obtained are 137.9 ± 0.9 Ma
by sensitive high-resolution ion microprobe (SHRIMP), and 139.55 ±
0.09/0.18 Ma by chemical-abrasion isotope-dilution thermal ionization
mass spectrometry (TIMS) near the base of the Berriasian. These new
ages can be interpreted in two different ways. The first alternative
would indicate that the present geological time table is correct and
the fossil levels should be late Berriasian. The second alternative is
that the J–K boundary is 5 Ma younger than the recently published
geological time scale. The authors support the last alternative and
propose that the J–K boundary should be close to 140 Ma.
Note that the 2013 International Chronostratigraphic Chart is available here:


Wild fires at end of Cretaceous

Emily L. Bamforth, Christine L. Button & Hans C.E. Larsson (2014)
Paleoclimate estimates and fire ecology immediately prior to the
end-Cretaceous mass extinction in the Frenchman Formation (66 Ma),
Saskatchewan, Canada.
Palaeogeography, Palaeoclimatology, Palaeoecology 401:  96–110
DOI: 10.1016/j.palaeo.2014.02.020


First paleoclimate estimates for the Late Cretaceous of Saskatchewan
Paleoclimate estimates derived from fossil leaf physiogamy
Paleoenvironment and biodiversity dynamics just prior to the K–Pg extinction
Paleoclimate comparisons of latest Cretaceous Western Interior Basin localities
Evidence of ecological recovery from local fire disturbance in the fossil record


The fossil-rich deposits of the uppermost Maastrichtian (66 Ma)
Frenchman Formation of southern Saskatchewan, Canada provide a
detailed, continuous record of terrestrial ecosystem dynamics during
the last half-million years leading up to the end-Cretaceous mass
extinction. Paleoenvironmental interpretations for the Frenchman
Formation are here refined by the first absolute paleoclimate
estimates for the Late Cretaceous of Saskatchewan, and by the
placement of these climate estimates within a North American context.
Climate estimates were calculated using Leaf Margin Analysis and the
Climate Leaf Analysis Multivariate Program (CLAMP), derived from two
independent plant macrofossil assemblages collected from the Frenchman
Formation. Climate parameter estimates indicate that the Maastrichtian
climate of southern Saskatchewan was subtropical to warm-temperate,
with mean annual temperatures between 12 °C and 14 °C, and with marked
seasonality. These results are comparable with estimates derived from
other late Campanian and Maastrichtian paleofloras in the Western
Interior Basin, although small variations among coeval localities were
noted or determined. Overall, the plant fossil assemblages from the
two study localities support the paleoenvironmental interpretation of
the Frenchman Formation as a swampy to lowland forest system with
canopy-forming deciduous conifers and a diverse, angiosperm-dominated
mid-canopy and understory. An unexpected, marked disparity in plant
diversity was found between the two paleofloras, despite the plant
assemblages returning similar paleoclimate parameter estimates.
Abundant in situ inertinite (fossil charcoal) deposits were found in
association with the less diverse paleofloral site, which contained
only angiosperm fossils. Inertinite was absent from the deposits
containing the more diverse paleoflora, which contained a different
composition of angiosperm and gymnosperm fossils. Fire is known to be
a prevalent feature of Late Cretaceous deposits worldwide, and modern
angiosperm plants typically are the first to recover following fire
disturbances. We suggest that the two Frenchman Formation paleofloras
represent different stages of secondary ecological succession
following a disturbance by fire. The identification of fire ecology in
the fossil record may have important implications for understanding
biodiversity patterns on small spatial and temporal scales immediately
prior to the Cretaceous mass extinction.

News story:


Permian amphibian swimming tracks
Fabio M. Petti,  Massimo Bernardi, Miriam A. Ashley-Ross, Fabrizio
Berra, Andrea Tessarollo & Marco Avanzini (2014)
Transition between terrestrial-submerged walking and swimming revealed
by Early Permian amphibian trackways and a new proposal for the
nomenclature of compound trace fossils.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
DOI: 10.1016/j.palaeo.2014.05.032

Exceptionally preserved Early Permian tetrapod trackways.
Producers are identified as small-sized temnospondyl or lepospondyl amphibians.
Trackways provide evidence for a transition from terrestrial walking
to swimming.
Evidence for conservatism of locomotor mechanics in amphibian evolution.
A new proposal of nomenclatural form to describe compound traces.


Exceptionally preserved Early Permian tetrapod trackways from the
Orobic Basin (Central-Western Southern Alps) offer a unique
opportunity to investigate in detail locomotion in fossil vertebrates
that lived on continental European landmasses. Herein are reported the
results of a study on several tetrapod trackways that display a large
variety of behavioural, gait and substrate related extramorphologies.
They clearly document the transition from terrestrial-underwater
walking to swimming and are assigned to the compound ichnotaxon
Batrachichnus C Lunichnium. The use of the “C” symbol is here
introduced for the first time as nomenclatural indication of a
Compound trace. Producers were probably small-sized temnospondyl or
lepospondyl (microsaurs) amphibians. Comparisons with living urodelan
anatomy and mechanics provide evidence for conservatism of locomotor
mechanics in evolutionary history among amphibians. The derived model
for locomotor kinematics in Early Permian amphibians provides a
reference for interpreting transitional land-to-water trackways. The
shift from walking to swimming behaviour in early tetrapods, as in
extant urodelan amphibians, is described as a complex balance between
different dynamics.



Alessandro Palci and Michael W. Caldwell (2014)
The Upper Cretaceous snake Dinilysia patagonica Smith-Woodward, 1901,
and the crista circumfenestralis of snakes.
Journal of Morphology (advance online publication)
DOI: 10.1002/jmor.20297

Studies on the phylogenetic relationships of snakes and lizards are
plagued by problematic characterizations of anatomy that are then used
to define characters and states in taxon-character matrices. State
assignments and character descriptions must be clear characterizations
of observable anatomy and topological relationships if homologies are
to be hypothesized. A supposed homology among snakes, not observed in
lizards, is the presence of a crista circumfenestralis (CCF), a system
of bony crests surrounding the fenestra ovalis and lateral aperture of
the recessus scalae tympani. We note that there are some fossil and
extant snakes that lack a CCF, and some extant lizards that possess a
morphological equivalent. The phylogenetically important upper
Cretaceous fossil snake Dinilysia patagonica has been interpreted by
different authors as either having or lacking a CCF. These conflicting
results for Dinilysia were tested by re-examining the morphology of
the otic region in a large sample of snakes and lizards. An
unambiguous criterion arising from the test of topology is used to
define the presence of a CCF: the enclosure of the ventral margin of
the juxtastapedial recess by flanges of the otoccipital (crista
tuberalis and crista interfenestralis) that extend forward to contact
the posterior margin of the prootic. According to this criterion D.
patagonica does not possess a CCF, therefore, this anatomical feature
must have arisen later during the evolution snakes.


Fritz Hertel, Jesús E. Maldonado, and Diego Sustaita (2014)
Wing and hindlimb myology of vultures and raptors (Accipitriformes) in
relation to locomotion and foraging.
Acta Zoologica (advance online publication)
DOI: 10.1111/azo.12074

Herein, we compare functional muscle properties among convergent forms
of large, obligate avian scavengers. We performed quantitative
analyses of all the muscle masses and cross-sectional areas (CSA) of
the wings and hindlimbs of five species from two families, Cathartidae
(New World vultures; Cathartes aura and Vultur gryphus) and
Accipitridae (Old World vultures and raptors; Gyps africanus, Aquila
rapax, and Buteo lineatus). These species comprise two paraphyletic
functional groups, raptors (Aquila and Buteo) and vultures (Gyps,
Cathartes, and Vultur). Our ordination analyses based on all of the
muscles of the wings, hindlimbs, and wing and hindlimb muscles
combined produced patterns that appeared to be more related to
phylogeny, with a hint of a functional signal in wing muscle CSA.
However, when wing muscles were grouped according to their functional
roles (upstroke, downstroke, and wing stabilization), the percentages
of mass and CSA allocated to the upstroke and stabilizing muscles were
1.4–5% greater in the vultures than in the raptors. Conversely, when
hindlimb muscles were grouped according to their roles in grasping and
terrestrial locomotion, the percentages of mass and CSA allocated to
grasping muscles were 5.9–14% greater in the raptors. Our results
provide a baseline for future lines of inquiry aimed at understanding
how muscle mass and CSA are affected differentially across locomotor
modules, possibly in response to differential demands on wing and
hindlimb function experienced by these disparate accipitriform clades.



Serendipaceratops identification needed mathematics




Scott Sampson interview



Hamipterus press release



Lego to produce female paleontologist