[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

New Mesozoic papers and news stories

From: Ben Creisler

A number of new papers related to the Mesozoic and some press releases
and news stories:

Luke Mander, Wolfram M. Kürschner and Jennifer C. McElwain (2013)
Palynostratigraphy and vegetation history of the Triassic–Jurassic
transition in East Greenland.
Journal of the Geological Society 170(1): 37-46
doi: 10.1144/jgs2012-018 170

We present a palynological study of a terrestrial Triassic–Jurassic
(Tr–J; c. 200 Ma) boundary section at Astartekløft, East Greenland. We
have generated a new palynostratigraphic scheme and vegetation history
for this locality, and have integrated these with existing carbon
isotope records. Samples for palynological analysis were collected
from precisely the same stratigraphic horizons as plant macrofossils
and samples used for geochemical analyses. Our results highlight four
local sporomorph assemblage zones that are compositionally distinct
from each other at Astartekløft. The extremely low abundance of
Classopollis pollen in all samples, and the pronounced decline of
Ricciisporites tuberculatus during the Late Rhaetian are notable
features of the sporomorph record of Tr–J vegetation at Astartekløft.
Correlation of Astartekløft and a marine Tr–J boundary section at St
Audrie’s Bay, UK, provides no support for the idea that extinction and
diversity loss in terrestrial ecosystems preceded biotic change in
marine ecosystems at the Tr–J. Instead, the available data support
suggestions that the onset of the Tr–J biotic crisis was synchronous
in terrestrial and marine environments. Peak extinction among plants
at Astartekløft occurred relatively late in the sequence of events
across the Tr–J, and may represent a response to long-term cumulative
effects of volcanism at this time.


Douglas S. Robertson, William M. Lewis, Peter M. Sheehan &
Owen B. Toon (2013)
K/Pg Extinction: Re-evaluation of the Heat/Fire Hypothesis.
Journal of Geophysical Research: Biogeosciences (advance online publication)
DOI: 10.1002/jgrg.20018

The global debris layer created by the end-Cretaceous impact at
Chicxulub contained enough soot to indicate that the entire
terrestrial biosphere had burned. Preliminary modeling showed that the
reentry of ejecta would have caused a global infrared pulse sufficient
to ignite global fires within a few hours of the Chicxulub impact.
This heat pulse and subsequent fires explain the terrestrial survival
patterns in the earliest Paleocene, since all the surviving species
were plausibly able to shelter from heat and fire underground or in
water. But new models of the global infrared heat pulse, as well as
the absence of charcoal, and the presence of noncharred organic
matter, have been said to be inconsistent with the idea of global
fires that could have caused the extinctions. It was suggested that
the soot in the debris layer originated from the impact site itself
because the morphology of the soot, the chain length of PAH's, and the
presence of carbon cenospheres were said to be inconsistent with
burning the terrestrial biosphere. These assertions are either
incorrect or have alternate explanations that are consistent with
global firestorms. We show that the apparent charcoal depletion in the
K-Pg layer has been misinterpreted due to a failure to correct
properly for sediment deposition rates. We will also show that the
mass of soot potentially released from the impact site is far too low
to supply the observed soot. But global firestorms are consistent with
both data and modeling.


Marcelo Reguero, Francisco Goin, Carolina Acosta Hospitaleche, Sergio
Marenssi & Tania Dutra (2013)
The Terrestrial Biotic Dimension of West Antarctica (WANT).
Late Cretaceous/Paleogene West Antarctica Terrestrial Biota and its
Intercontinental Affinities: 55-110
DOI: 0.1007/978-94-007-5491-1_5

The Late Cretaceous terrestrial biota from Antarctica come from the
marine sediments of the James Ross Basin and the western flank of the
Antarctic Peninsula. A compilation of data for Cretaceous and
Paleogene Antarctic floras from these areas provides different
perspective on floristic and vegetation change when compared with
those coeval floras from southern South America.The Paleogene sequence
in southern South America (Patagonia) and the Antarctic Peninsula
reveals floristically distinct periods (late Paleocene, early and
middle Eocene and latest Eocene), based largely on leaf assemblages.
The La Meseta paleoflora is distinctive in having a predominance of
Antarctic taxa especially Nothofagus, podocarps, and araucarian
conifers in the Eocene deciduous and evergreen forests. This suggests
a cooling trend during the Eocene of Antarctica with mid- to late
Eocene seasonal, cool-temperate, rainy climates and latitudinal and
altitudinal gradients. In the Late Cretaceous of James Ross Basin at
least nine taxa of non-avian dinosaurs (a megalosaur-like theropod, a
nodosaurid ankylosaur, a dromaeosaurid theropod, an iguanodontid, a
hypsilophodontid, and a large-bodied lithostrotian titanosaur) and at
least four avian dinosaurs have been reported or described from the
Campanian/Maastrichtian deposits of this basin. Additional non-avian
dinosaur evidence from the same area is based upon the occurrence of
Maastrichtian sauropod? footprints of Snow Hill Island. In the
Paleogene, of the six allomembers of the La Meseta Formation, only
three, Acantilados (Ypresian), Cucullaea I (Ypresian/Lutetian) and
Submeseta (Priabonian), contain endemic terrestrial mammals
(metatherians and meridiungulates) and birds. Seafloor spreading
between Antarctic Peninsula (West Antarctica) and South America
possibly opened an intermittent seaway by the end of the Paleocene
(Thanetian, 55 Ma) but subsequent tectonic and sedimentary events may
have delayed the final break up between the two continents until the
end of the Late Eocene (Priabonian, 34 Ma) with the opening of the
Drake Passage.


Diego Sustaita, Emmanuelle Pouydebat, Adriana Manzano, Virginia Abdala,
Fritz Hertel & Anthony Herrel (2013)
Getting a grip on tetrapod grasping: form, function, and evolution.
Biological Reviews (advance online publication)
DOI: 10.1111/brv.12010

Human beings have been credited with unparalleled capabilities for
digital prehension grasping. However, grasping behaviour is widespread
among tetrapods. The propensity to grasp, and the anatomical
characteristics that underlie it, appear in all of the major groups of
tetrapods with the possible exception of terrestrial turtles. Although
some features are synapomorphic to the tetrapod clade, such as
well-defined digits and digital musculature, other features, such as
opposable digits and tendon configurations, appear to have evolved
independently in many lineages. Here we examine the incidence,
functional morphology, and evolution of grasping across four major
tetrapod clades. Our review suggests that the ability to grasp with
the manus and pes is considerably more widespread, and ecologically
and evolutionarily important, than previously thought. The
morphological bases and ecological factors that govern grasping
abilities may differ among tetrapods, yet the selective forces shaping
them are likely similar. We suggest that further investigation into
grasping form and function within and among these clades may expose a
greater role for grasping ability in the evolutionary success of many
tetrapod lineages.


Press releases and news stories

Oviraptor feathered tails used for courting



Jeholosaurus anatomy

Stolen dinosaur track in Colorado