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Jehol Biota mass mortality events + niche use across Komodo dragon ontogeny + more papers



Ben Creisler
bcreisler@gmail.com

Some recent non-dino papers that may be of interest:

Lian Zhou, Thomas J. Algeo, Lanping Feng, Rixiang Zhu, Yongxin Pan,
Shan Gao, Laishi Zhao & Yuanbao Wu (2016)
Relationship of pyroclastic volcanism and lake-water acidification to
Jehol Biota mass mortality events (Early Cretaceous, northeastern
China).
Chemical Geology (advance online publication)
doi:10.1016/j.chemgeo.2016.02.029
http: // www.sciencedirect.com/science/article/pii/S0009254116301036

Highlights

The world-famous Jehol Biota fossil lagerstätte accumulated in Ancient
Lake Sihetun
Lake Sihetun was an Early Cretaceous volcanic caldera lake (maar) in NE China
Lake sediments record four cycles of pyroclastic eruption and lake
chemistry change
Lakewater chemistry fluctuated from acidic to alkaline during each
eruption cycle
Low molybdenum isotope values (δ98/95Mo = –2.50‰) document hydrothermal inputs

Abstract

Geochemical analysis of the 14.4-m-thick lacustrine succession of the
Lower Cretaceous Yixian Formation (Jehol Group) has yielded new
insights concerning vertebrate mass mortality events in the Lake
Sihetun volcanic caldera in western Liaoning Province (northeastern
China) that produced the Jehol Biota fossil lagerstätten. The
long-term evolution of the caldera system resulted in a shift from
felsic to mafic magma chemistry, accompanied by a reduced frequency of
pyroclastic eruptions, declining hydrothermal activity, and lower
lacustrine productivity. The basal Tetrapod Beds exhibit strong
hydrothermal influence, as indicated by enrichments of boron (B),
certain alkalis (Rb, Cs), rare-earth elements (REEs), yttrium (Y), and
many metals (e.g., Co, Cr, Cu, Ge, Mo, Ni, Sb, U, V, and W), and by
strongly negative molybdenum isotope compositions (δ98Mo to –2.50‰)
that may record large fractionations between molybdate and
thiomolybdate species in the Sihetun caldera hydrothermal system. In
contrast, the overlying Fish Beds and Non-Fossiliferous Beds have an
elemental and Mo-isotopic composition similar to calc-alkaline basalts
(δ98Mo = –0.29 ± 0.04‰) in the surrounding watershed, suggesting
weathering of Yixian Formation volcanic rocks as the major source of
sediment. During its < 700-kyr-long history, Lake Sihetun was affected
by four environmental cycles, each commencing with a series of
pyroclastic eruptions that triggered systematic changes in lakewater
chemistry. Following each eruption interval, enhanced weathering of
volcanic ash in the surrounding watershed caused lakewater pH to
decrease and lacustrine productivity to increase. Continued weathering
of bases from basement volcanic rocks subsequently produced alkaline
conditions in the lake, leading to precipitation of authigenic
carbonate layers and lower lacustrine productivity. Analysis of
geochemical redox proxies strongly suggests that the Lake Sihetun
water column was completely oxic, in contrast to earlier inferences of
a stratified anoxic water column, and that ubiquitous lamination in
the lacustrine succession was due to other factors such as widespread
microbial mats and/or rapid sediment deposition.

===

Deni Purwandana, Achmad Ariefiandy, M. Jeri Imansyah, Aganto Seno,
Claudio Ciofi, Mike Letnic & Tim S. Jessop (2016)
Ecological allometries and niche use dynamics across Komodo dragon ontogeny.
The Science of Nature (advance online publication)
DOI: 10.1007/s00114-016-1351-6
http: // link.springer.com/article/10.1007/s00114-016-1351-6

Ontogenetic allometries in ecological habits and niche use are key
responses by which individuals maximize lifetime fitness. Moreover,
such allometries have significant implications for how individuals
influence population and community dynamics. Here, we examined how
body size variation in Komodo dragons (Varanus komodoensis) influenced
ecological allometries in their: (1) prey size preference, (2) daily
movement rates, (3) home range area, and (4) subsequent niche use
across ontogeny. With increased body mass, Komodo dragons increased
prey size with a dramatic switch from small (≤10 kg) to large prey
(≥50 kg) in lizards heavier than 20 kg. Rates of foraging movement
were described by a non-linear concave down response with lizard
increasing hourly movement rates up until ~20 kg body mass before
decreasing daily movement suggesting reduced foraging effort in larger
lizards. In contrast, home range area exhibited a sigmoid response
with increased body mass. Intrapopulation ecological niche use and
overlap were also strongly structured by body size. Thus, ontogenetic
allometries suggest Komodo dragon’s transition from a highly active
foraging mode exploiting small prey through to a less active sit and
wait feeding strategy focused on killing large ungulates. Further, our
results suggest that as body size increases across ontogeny, the
Komodo dragon exhibited marked ontogenetic niche shifts that enabled
it to function as an entire vertebrate predator guild by exploiting
prey across multiple trophic levels.


====

Jan Ove R. Ebbestad (2016)
Carl Wiman and the foundation of Mesozoic vertebrate palaeontology in Sweden.
Geological Society, London, Special Publications 434: Mesozoic Biotas
of Scandinavia and its Arctic Territories.
doi:10.1144/SP434.15
http: // sp.lyellcollection.org/content/early/2016/02/26/SP434.15.abstract

In 1908, Carl Wiman of Uppsala University, Sweden, discovered rich
horizons with Triassic vertebrate remains in Spitsbergen on Svalbard,
Norway. This marked the beginning of vertebrate palaeontology as a
science in Sweden, subsequently developed mainly through the
collection and study of non-Swedish fossil remains. Wiman's
accomplishments, resolute personality and a tight network of
influential friends and supporters enabled him to become the first
person in Sweden to hold a university chair in Palaeontology and
Historical Geology. He also managed to amass large numbers of unique
fossil vertebrate specimens culminating in an extensive Chinese
collection of both world famous dinosaurs and Neogene mammals
deposited at Uppsala University. Joint scientific Sino-Swedish
collaboration and a deliberate Swedish scientific agenda ensured this
unprecedented situation in an opportune moment. Governmental support
and initiative allowed Uppsala University and Carl Wiman's
Palaeontological Institute to erect a museum building dedicated
foremost to the Chinese material, now known as the Lagrelius
Collection in recognition of the patron behind Wiman's ambitious
endeavours. In addition, the museum served as a permanent repository
for seminal collections of Mesozoic fossils from Svalbard and North
America. Collectively, these represent a landmark research and
teaching resource that remains of intense scientific interest even
today.

=====

Juan Marcos Jannello, Ignacio A. Cerda & Marcelo S. de la Fuente (March 2016)
Shell bone histology of the long-necked chelid Yaminuechelys
(Testudines: Pleurodira) from the late Cretaceous—early Palaeocene of
Patagonia with comments on the histogenesis of bone ornamentation.
The Science of Nature (advance online publication)
DOI: 10.1007/s00114-016-1346-3
http: // link.springer.com/article/10.1007/s00114-016-1346-3

Yaminuechelys is a long-necked chelid turtle whose remains have been
recovered from outcrops of the Santonian-Maastrichtian and Danian of
South America. With the purpose of providing data about shell
sculpturing origin and palaeoecology, the bone histology of several
shell elements (including neural, costal, peripheral and plastral
plates) of Yaminuechelys is described herein. Histological analysis
reveals that Yaminuechelys shares with Chelidae the presence of
interwoven structural fibre bundles in the external cortex, and
parallel-fibred bone of the internal cortex. The presence of
resorption lines in several samples indicates that the particular
ornamentation of the external surfaces originated, at least in part,
by focalized resorption and new bone deposition. This mechanism for
ornamentation origin and maintenance is here described for the first
time in a turtle. Compactness of the shell bones is consistent with an
aquatic habitat, which supports previous hypothesis based on
palaeoenvironmental and morphological data.

===

James D. Gardner & Jean-Claude Rage (2016)
The fossil record of lissamphibians from Africa, Madagascar, and the
Arabian Plate.
Palaeobiodiversity and Palaeoenvironments (advance online publication)
DOI: 10.1007/s12549-015-0221-0
http: // link.springer.com/article/10.1007/s12549-015-0221-0


Lissamphibians (frogs, salamanders, caecilians, and the extinct
Albanerpetontidae) have a near global distribution. Africa, its
associated islands (especially Madagascar and the Seychelles) and the
Arabian Plate are home to about 27 families (including 15 endemic) and
1135 species of extant lissamphibians or about 38 and 15 %,
respectively, of the global totals. The region also contains an
extensive, but patchy and somewhat under-appreciated fossil record.
Based on published and unpublished information, we provide here the
most comprehensive review to date of the lissamphibian fossil record
from the region. We also discuss the insights those occurrences
provide into past distributions and diversities of lissamphibians in
the region and the establishment of the modern fauna. Our review
relies on occurrence data from 93 sets of localities of basal Triassic
through Holocene age, distributed across 23 countries. As with the
modern lissamphibian fauna of the region, the fossil record is
dominated by frogs, but there also are notable occurrences of other
lissamphibians, including several genera of enigmatic Cretaceous
salamanders, one of two known stem caecilians, and the only Gondwanan
records for albanerpetontids. Africa is one of only two continents
(the other being North America) to have occurrences for all four
lissamphibian clades. Twenty named and currently accepted fossil
lissamphibian species are recognised from the region: one stem and 14
crown frogs (11 or possibly 12 of which are pipimorphs, 1 alytid, and
1 neobatrachian possibly referable to the otherwise exclusively South
American families Ceratophryidae or Calyptocephalellidae); three
salamanders; one stem caecilian; and one albanerpetontid. Additional
and as yet unnamed taxa are represented in existing collections, and
others undoubtedly remain to be discovered. Of the 27 extant
lissamphibian families currently recognised from the region, 12 of 22
frog families (including five endemics: Brevicipitidae,
Heleophrynidae, Hyperoliidae, Ptychadenidae, and Pyxicephalidae) and
the sole salamander family (Salamandridae) have fossil records; at
present, none of the known caecilian fossils can be assigned with
confidence to any of the four extant families currently recognised in
the region. The biogeographic histories of lissamphibians in Africa,
its associated islands and the Arabian Plate are characterised by
vicariant and dispersal events related to the complex palaeogeographic
history of the region.

===

Mike Pole, Yongdong Wang, Eugenia V. Bugdaeva, Chong Dong, Ning Tian,
Liqin Li & Ning Zhou (2016)
The rise and demise of Podozamites in East Asia – An extinct conifer life style.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
doi:10.1016/j.palaeo.2016.02.037
http: // www.sciencedirect.com/science/article/pii/S0031018216001188


Highlights

Podozamites became widespread at mid latitudes in the Late Triassic
Formed extensive deciduous forests
Migrated/contracted polewards over the Mesozoic
Became extinct in the Late Cretaceous
Was possibly out-competed by angiosperms

Abstract

In the Late Triassic–Early Jurassic, forests dominated by
Podozamites—an apparently deciduous, shoot-dropping conifer with
broad, multi-veined leaves—were extensive in what were the
mid-latitudes of eastern Asia. Podozamites was the only conifer in
many forests of this region, and at times appeared to have formed an
almost mono-specific vegetation. Podozamites appears to have been
little-effected through the Triassic–Jurassic transition, but
responded to climate changes later in the Jurassic. The Chinese region
progressively dried through the Middle Jurassic and aridity had
developed in some areas by the Late Jurassic–Early Cretaceous. The
centre of distribution of Podozamites shifted north, to the Siberian
region, where conditions remained wet. There, it typically coexisted
with conifers having a diverse range of smaller leaf morphologies.

By the late Albian angiosperms had arrived in the Siberian area and
risen to dominance. Some time after this event, Podozamites became
extinct. This is significant, as it represents the permanent
extinction of a unique lifestyle—a deciduous, broad-leaved and
multi-veined conifer.

The broad history of Podozamites raises some interesting issues:

1.
The existence of a large, dominantly deciduous vegetation at
mid-latitudes in the Late Triassic–Early Jurassic is little discussed.
2.
It is unexpected that as broad-leaved angiosperms took over, among the
conifers it was the broad leaved, multi-veined Podozamites that became
extinct. This is the morphology that might have been expected to
compete with the apparently more shade-forming angiosperms. Instead,
it was the smaller leaved and single-veined conifers that remained to
coexist with the angiosperms.

===


J. V. Proffitt, J. A. Clarke and R. P. Scofield (2016)
Novel insights into early neuroanatomical evolution in penguins from
the oldest described penguin brain endocast.
Journal of Anatomy (advance online publication)
DOI: 10.1111/joa.12447
http: // onlinelibrary.wiley.com/doi/10.1111/joa.12447/abstract

Digital methodologies for rendering the gross morphology of the brain
from X-ray computed tomography data have expanded our current
understanding of the origin and evolution of avian neuroanatomy and
provided new perspectives on the cognition and behavior of birds in
deep time. However, fossil skulls germane to extracting digital
endocasts from early stem members of extant avian lineages remain
exceptionally rare. Data from early-diverging species of major avian
subclades provide key information on ancestral morphologies in Aves
and shifts in gross neuroanatomical structure that have occurred
within those groups. Here we describe data on the gross morphology of
the brain from a mid-to-late Paleocene penguin fossil from New
Zealand. This most basal and geochronologically earliest-described
endocast from the penguin clade indicates that described
neuroanatomical features of early stem penguins, such as lower
telencephalic lateral expansion, a relatively wider cerebellum, and
lack of cerebellar folding, were present far earlier in penguin
history than previously inferred. Limited dorsal expansion of the
wulst in the new fossil is a feature seen in outgroup waterbird taxa
such as Gaviidae (Loons) and diving Procellariiformes (Shearwaters,
Diving Petrels, and allies), indicating that loss of flight may not
drastically affect neuroanatomy in diving taxa. Wulst enlargement in
the penguin lineage is first seen in the late Eocene, at least 25
million years after loss of flight and cooption of the flight stroke
for aquatic diving. Similar to the origin of avian flight, major
shifts in gross brain morphology follow, but do not appear to evolve
quickly after, acquisition of a novel locomotor mode. Enlargement of
the wulst shows a complex pattern across waterbirds, and may be linked
to sensory modifications related to prey choice and foraging strategy.

News:
https://urldefense.proofpoint.com/v2/url?u=http-3A__phys.org_news_2016-2D03-2Dpenguin-2Dbrains-2Dloss-2Dflight.html&d=CwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=x82f3Wlkwtmbr1z8IAt9jA&m=o8wsqm9bW40yZm_eOpc7ARRIRBLhKZCoa7E2Ajvd2eU&s=pveGprEoAm1Kjyagnf7Ox9UJZutM12KWu3QhlXaGUYk&e=
 



=======================

Hervé Bocherens, Martin Cotte, Ricardo Bonini, Daniel Scian, Pablo
Straccia, Leopoldo Soibelzon, Francisco J. Prevosti
Paleobiology of sabretooth cat Smilodon populator in the Pampean
Region (Buenos Aires Province, Argentina) around the Last Glacial
Maximum: Insights from carbon and nitrogen stable isotopes in bone
collagen.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
doi:10.1016/j.palaeo.2016.02.017
http: // www.sciencedirect.com/science/article/pii/S0031018216000912

Highlights

The sabretooth cat Smilodon populator was the largest felid in South America
First δ13C and δ15N for Smilodon from 25 to 10 kyr BP in the Pampas
Predator of large prey from open landscape (Macrauchenia, giant ground sloths)
Smilodon was possibly competing with the large canid Protocyon but not
with jaguar
Holocene climate change may have contributed to its extinction


Abstract

The sabretooth cat Smilodon populator was the largest felid in South
America. It appears in the fossil record in the Early Pleistocene, as
an immigrant from North America, and becomes extinct around the
Pleistocene-Holocene boundary. The carbon and nitrogen stable isotopic
values of collagen were measured for skeletal remains from Smilodon
specimens ranging in age from 25 to 10 kyr BP, for the first time in
the Pampas region of Argentina. By comparison with similar values
obtained on co-eval predators such as Protocyon (large canid) and
Panthera onca (jaguar) and a range of potential prey, such as giant
ground sloths, glyptodontids, Macrauchenia, Toxodon, equids, cervids,
and rodents, it could be established that Smilodon consumed
essentially large prey from open landscape, such as Macrauchenia and
giant ground sloths during the last 15,000 years of the Late
Pleistocene in the Pampa region. It was possibly competing with the
large canid Protocyon but jaguar was apparently feeding on smaller
size prey. A more humid climate at the beginning of the Holocene might
have been unfavorable to this large predator and could have
contributed to its extinction. These results also provide important
insight to understand the ecological processes involved in the Great
American Biotic Interchange.
===