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Pathological pitting in ankylosaur osteoderms + vertebrate coprolite diversity at end-Permian extinction + more



Ben Creisler
bcreisler@gmail.com

Some recent refs, mainly non-dino related:

Angela E. Matthias, Lorrie A. McWhinney & Kenneth Carpenter (2016)
Pathological pitting in ankylosaur (Dinosauria) osteoderms.
International Journal of Paleopathology 13: 82-90
doi:10.1016/j.ijpp.2016.02.006
http: // www.sciencedirect.com/science/article/pii/S1879981716300122

Highlights

Pathological dermatoses of ankylosaur osteoderms.
Use of Istanbul Protocol narrows possible causes.
Microbial ulceration or pressure erosion.

Abstract

Large ulcerative pits on the external surface of ankylosaur
(Dinosauria) osteoderms have been recognized for many years. They have
been ascribed without supporting evidence to damage by predator teeth
or to disease. The discovery of numerous examples of pitted osteoderms
in a monospecific ankylosaur (Gastonia n.sp.) bone bed in eastern Utah
(USA) provided a unique opportunity to study these pits in greater
detail. The pits typically are characterized by smooth-walled
depressions that disrupt the bone surface, with 43% focal lesions and
57% multifocal. Because ankylosaur osteoderms are analogous to
crocodile osteoderms, the possible etiology of the pits was sought
among today’s crocodile dermatoses. A modified version of the Istanbul
Protocol was used to indicate the degree of certainty for the possible
causes. This technique in context of the limited range of response to
infection of reptile bone, allows us to narrow the possible causes of
pit formation to two. One is ulceration by bacterial or mycological
dermatosis; the other is through pressure erosion of the bone surface
(cortex) by granuloma formation in the thin skin or at the
skin-osteoderm interface. Unfortunately, the biopsies that are
critical for differential diagnosis of diseases in modern reptiles
cannot be performed on the ankylosaur osteoderms. Therefore, a single
definitive etiology for pits in ankylosaurs cannot be identified.

===


Grzegorz Niedźwiedzki, Piotr Bajdek, Martin Qvarnström, Tomasz Sulej,
Andrey G. Sennikov & Valeriy K. Golubev (2016)
Reduction of vertebrate coprolite diversity associated with the
end-Permian extinction event in Vyazniki region, European Russia.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
doi:10.1016/j.palaeo.2016.02.057
http: // www.sciencedirect.com/science/article/pii/S0031018216001590


Highlights

The Permo-Triassic section at Vyazniki contains a rich accumulation of
coprolites.
Coprolites were produced by a number of different vertebrate taxa.
Coprolites are grouped into nine morphotypes and linked to producers.
There is a reduction of coprolite morphotypes after of the end-Permian
extinction.
The reduction of coprolite diversity reflects the disappearance of
vertebrate taxa.

Abstract

This study investigates the paleoecological significance of vertebrate
coprolites collected from seven sections and three lithofacies of the
uppermost Permian and lowermost Triassic succession from the Vyazniki
site in the European part of Russia. The analysed specimens
(coprolites and possibly some cololites) were grouped into nine
morphotypes (A–I).The coprolite morphotypes were characterized
geochemically and compared to the record of other Permian and Triassic
coprolites worldwide. Based on the stratigraphic position, shape,
structure and composition, all morphotypes were linked to supposed
producers. The phosphatic composition of most of the morphotypes and
inclusions of arthropod remains, fish scales and bone fragments,
suggest that they were produced by carnivores, but non-phosphatic,
carbonate-rich, large and oval-shaped coprolites with impressions
after plant remains have also been found. The extinction of
terrestrial vertebrates around the Permian–Triassic boundary in Russia
is interpreted to have occurred within a few thousands of years. Here,
we show a pattern of coprolite morphotypes disappearing across this
boundary that is consistent with a relatively sudden change in the
vertebrate faunal composition across this interval.

===



Carys E. Bennett, Timothy I. Kearsey, Sarah J. Davies, David Millward,
Jennifer A. Clack, Timothy R. Smithson andJohn E. A. Marshall (2016)
Early Mississippian sandy siltstones preserve rare vertebrate fossils
in seasonal flooding episodes.
Sedimentology (advance online publication)
DOI: 10.1111/sed.12280
http: // onlinelibrary.wiley.com/doi/10.1111/sed.12280/abstract


Flood-generated sandy siltstones are under-recognised deposits that
preserve key vertebrate (actinopterygians, rhizodonts, and rarer
lungfish, chondrichthyans and tetrapods), invertebrate and plant
fossils. Recorded for the first time from the Lower Mississippian
Ballagan Formation of Scotland, more than 140 beds occur throughout a
490 m thick core succession characterised by fluvial sandstones,
palaeosols, siltstones, dolostone ‘cementstones’ and gypsum from a
coastal–alluvial plain setting. Sandy siltstones are described as a
unique taphofacies of the Ballagan Formation. They are
matrix-supported siltstones with millimetre-sized siltstone and very
fine sandstone lithic clasts. Common bioclasts include plants and
megaspores, fish, ostracods, eurypterids and bivalves. Fossils have a
high degree of articulation compared with those found in other
fossil-bearing deposits such as conglomerate lags at the base of
fluvial channel sandstones. Bed thickness and distribution varies
throughout the formation, with no stratigraphic trend. The matrix
sediment and clasts are sourced from the reworking of floodplain
sediments including desiccated surfaces and palaeosols. Secondary
pedogenic modification affects 30% of the sandy siltstone beds and
most (71%) overlie palaeosols or desiccation cracks. Sandy siltstones
are interpreted as cohesive debris flow deposits that originated by
the overbank flooding of rivers and due to localised floodplain
sediment transport at times of high rainfall; their association with
palaeosols and desiccation cracks indicates seasonally wet to dry
cycles throughout the Tournaisian. Tetrapod and fish fossils derived
from floodplain lakes and land surfaces are concentrated by local
erosion and reworking and are preserved by deposition into temporary
lakes on the floodplain; their distribution indicates a local origin,
with sediment distributed across the floodplain in seasonal rainfall
episodes. These deposits are significant new sites that can be
explored for the preservation of rare non-marine fossil material and
provide unique insights into the evolution of early terrestrial
ecosystems.

===

Glenn J. Tattersall (2016)
Reptile thermogenesis and the origins of endothermy.
Zoology (advance online publication)
doi:10.1016/j.zool.2016.03.001
http: // www.sciencedirect.com/science/article/pii/S0944200616300137

Highlights

Proposed proximate and ultimate origins of endothermy in vertebrates
are numerous.
In this context, all possible heat generation and heat conservation
capacities need to be considered.
The reproductive capacity/parent care model for endothermy has
received recent support from tegu lizards.

Abstract

Extant endotherms have high rates of metabolism, elevated body
temperatures, usually tight control over body temperature, and a
reasonable scope for further increases in metabolism through locomotor
activity. Vertebrate ectotherms, on the other hand, rely on
behavioural thermoregulation and cardiovascular adjustments to
facilitate warming, and generally lack specific biochemical and
cellular mechanisms for sustained, elevated metabolism. Nevertheless,
the ancestral condition to endothermy is thought to resemble that of
many extant reptiles, which raises the question of the origins and
selection pressures relevant to the transitional state. Numerous
hypotheses have emerged to explain the multiple origins of endothermy
in vertebrates, including thermoregulatory, locomotory, and
reproductive activity as possible drivers for these sustained and
elevated metabolic rates. In this article, I discuss recent evidence
for facultative endothermy in an extant lepidosaur, the tegu lizard.
Since lepidosaurs are a sister group to the archosaurs, understanding
how a novel form of endothermy evolved will open up opportunities to
test the compatibility or incompatibility of the various endothermy
hypotheses, with potential to elucidate and resolve long contentious
ideas in evolutionary physiology.

**

Earlier open access article not yet mentioned on the DML:

Glenn J. Tattersal, Cleo A. C. Leite, Colin E. Sanders, Viviana
Cadena, Denis V. Andrade, Augusto S. Abe and William K. Milsom (2016)
Seasonal reproductive endothermy in tegu lizards
Science Advances  2(1):  e1500951
DOI: 10.1126/sciadv.1500951
http: // advances.sciencemag.org/content/2/1/e1500951

With some notable exceptions, small ectothermic vertebrates are
incapable of endogenously sustaining a body temperature substantially
above ambient temperature. This view was challenged by our
observations of nighttime body temperatures sustained well above
ambient (up to 10°C) during the reproductive season in tegu lizards
(~2 kg). This led us to hypothesize that tegus have an enhanced
capacity to augment heat production and heat conservation. Increased
metabolic rates and decreased thermal conductance are the same
mechanisms involved in body temperature regulation in those
vertebrates traditionally acknowledged as “true endotherms”: the birds
and mammals. The appreciation that a modern ectotherm the size of the
earliest mammals can sustain an elevated body temperature through
metabolic rates approaching that of endotherms enlightens the debate
over endothermy origins, providing support for the parental care model
of endothermy, but not for the assimilation capacity model of
endothermy. It also indicates that, contrary to prevailing notions,
ectotherms can engage in facultative endothermy, providing a
physiological analog in the evolutionary transition to true
endothermy.

News

http: // 
agencia.fapesp.br/giant_tegu_lizard_is_warmblooded_researchers_discover/22723/

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