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Monitor lizard unidirectional breathing and other non-dino papers

From: Ben Creisler

A number of recent non-dino papers that may be of interest:

Emma R. Schachner, Robert L. Cieri, James P. Butler & C. G. Farmer (2013)
Unidirectional pulmonary airflow patterns in the savannah monitor lizard.
Nature (advance online publication)

The unidirectional airflow patterns in the lungs of birds have long
been considered a unique and specialized trait associated with the
oxygen demands of flying, their endothermic metabolism1 and unusual
pulmonary architecture2, 3. However, the discovery of similar flow
patterns in the lungs of crocodilians indicates that this character is
probably ancestral for all archosaurs—the group that includes extant
birds and crocodilians as well as their extinct relatives, such as
pterosaurs and dinosaurs4, 5, 6. Unidirectional flow in birds results
from aerodynamic valves, rather than from sphincters or other physical
mechanisms7, 8, and similar aerodynamic valves seem to be present in
crocodilians4, 5, 6. The anatomical and developmental similarities in
the primary and secondary bronchi of birds and crocodilians suggest
that these structures and airflow patterns may be homologous4, 5, 6,
9. The origin of this pattern is at least as old as the split between
crocodilians and birds, which occurred in the Triassic period10.
Alternatively, this pattern of flow may be even older; this hypothesis
can be tested by investigating patterns of airflow in members of the
outgroup to birds and crocodilians, the Lepidosauromorpha (tuatara,
lizards and snakes). Here we demonstrate region-specific
unidirectional airflow in the lungs of the savannah monitor lizard
(Varanus exanthematicus). The presence of unidirectional flow in the
lungs of V. exanthematicus thus gives rise to two possible
evolutionary scenarios: either unidirectional airflow evolved
independently in archosaurs and monitor lizards, or these flow
patterns are homologous in archosaurs and V. exanthematicus, having
evolved only once in ancestral diapsids (the clade encompassing
snakes, lizards, crocodilians and birds). If unidirectional airflow is
plesiomorphic for Diapsida, this respiratory character can be
reconstructed for extinct diapsids, and evolved in a small ectothermic
tetrapod during the Palaeozoic era at least a hundred million years
before the origin of birds.

News stories:





Plant fossils suggest Arctic dinosaurs migrated south for the winter

A. B. Herman (2013)
Stratigraphy and Geological Correlation 21(7): 689-747
Albian-Paleocene flora of the north pacific: Systematic composition,
palaeofloristics and phytostratigraphy.
DOI: 10.1134/S0869593813070034

Principal attention is focused on phytostratigraphy and comparative
palaeofloristics of the Anadyr-Koryak (AKSR) and Northern Alaska
(NASR) subregions of the North Pacific Region. The high-resolution
Upper Albian-Paleocene phytostratigraphic schemes of these subregions
are based on perceived stages of their floral evolution. In the AKSR
the scheme includes seven subdivisions of subregional extent: the
Early Ginter (upper Albian), Grebenka (upper Albian-Cenomanian-lower
Turonian), Penzhina (upper Turonian), Kaivayam (Coniacian), Barykov
(Santonian-lower to ?middle Campanian), Gornorechenian (?upper
Campanian-lower Maastrichtian), and Koryak (lower to upper
Maastrichtian-?Danian) phytostratigraphic horizons. The
phytostratigraphic scheme of the NASR includes three subregional
phytostratigraphic horizons and five plant-bearing beds. These are the
Kukpowruk (?lower to middle-?upper Albian), Niakogon (upper
Albian-Cenomanian), Kaolak (Turonian) horizons and beds with the
Tuluvak (Coniacian), Early Kogosukruk (upper Santonian-Campanian),
Late Kogosukruk (Campanian-Maastrichtian), Early Sagwon
(Danian-Selandian), and Late Sagwon (Selandian-Thanetian) floras. The
comparative analysis of coeval (or close in age) floras distinguished
in the AKSR and NASR shows that they are either similar to each other
(floras Early Ginter and Kukpowruk, Grebenka and Niakogon, Penzhina
and Kaolak, Koryak and Early Sagwon) or different in systematic
composition (floras Kaivayam and Tuluvak, Gornorechenian and
Kogosukruk). Similarities between the floras imply that plant
assemblages of two subregions evolved under comparable climatic
conditions and freely intercommunicated via the Bering Land Bridge
during the Albian-Turonian and terminal Maastrichtian-Paleocene.
Floras of the AKSR and NASR, which are of different composition,
existed in particular intervals of geological history when
trans-Beringian plant migrations were limited or even ceased because
of palaeoclimatic difference between the subregions. Floras of the
AKSR and NASR survived crisis at the Cretaceous-Paleogene boundary
without essential evolutionary consequence which does not support a
hypothesis of a global ecological crisis at this boundary. From the
analysis of the Arctic end-Cretaceous flora and palaeoclimate we
conclude that the large Northern Alaskan dinosaurs were driven by lack
of resources (food and shelter) to migrate 1200–1300 kilometres to the
South to find forage, warmer temperatures and better light conditions
before winter set in. A scenario of the Albian-Late Cretaceous
florogenesis in the North Pacific Region is proposed. A primary driver
of Albian-Late Cretaceous florogenesis was the gradual invasion by
novel angiosperm-rich plant communities into the Asiatic continental
interiors and a replacement of pre-existing vegetation dominated by
ancient ferns and gymnosperms. Plant fossils representing Mesophytic
and Cenophytic communities usually do not mix in the individual


Jurassic turtle from Germany

Maren Jansen & Nicole Klein (2013)
A juvenile turtle (Testudines, Eucryptodira) from the Upper Jurassic
of Langenberg Quarry, Oker, Northern Germany.
Palaeontology (advance online publication)
DOI: 10.1111/pala.12085

Turtles are frequently found in fluviatile to lagoonal and shallow
marine sediments in the Upper Jurassic of Western Europe. These
turtles usually show a mixture of basal and derived characters, but
phylogenetic relationships are still largely unresolved. This is
mainly due to the incompleteness of fossils and the lack of
taxonomically unambiguous characters and is also related to the
presence of different ontogenetic stages, which are not easy to
compare. The morphological description of a new turtle from the Upper
Jurassic of Langenberg Quarry (Oker, Lower Saxony, Germany) gives
further insights into the ontogeny of basal eucryptodire turtles as
well as into aquatic adaptation of Upper Jurassic turtles. The
specimen is herein left in open nomenclature, due to the fact that it
represents a juvenile individual. Several characters define the
specimen as juvenile: its small size (7.28 cm carapace length);
lateral carapacial fontanelles; enlarged vertebral scutes; a radial
striation pattern covering the entire carapace; and the grade of
ossification of preserved skull and limb elements. A clear aquatic
adaptation of the individual is the elongated manus, a feature that is
independent of ontogenetic age. The elongated manus may indicate a
marine lifestyle and the individual possibly inhabited nearshore to
offshore areas around the former Jurassic islands, which today form
the Saxony Basin. The ossification pattern of the carapace of this
eucryptodire turtle resembles that of known Jurassic paracryptodires
and thus provides new insights to the ontogeny of Jurassic turtles.