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Plesiosaur pectoral girdle soft-tissue anatomy + more papers
A number recent non-dino papers
Ricardo Araújo and Fernando Correia (2015)
Soft-tissue anatomy of the Plesiosaur pectoral girdle inferred from
basal Eosauropterygia taxa and the extant phylogenetic bracket.
Palaeontologia Electronica 18.1.8A: 1-32.
Plesiosaurians are highly derived secondarily-adapted organisms (if
fishes are primarily-adapted) with a long evolutionary history, and
they are closely related with basal eosauropterygians. Attempts to
reconstruct soft-tissue anatomy can be complicated due to the lack of
extant closely-related species, thus various lines of evidence must be
considered. This study aims to reconstruct the pectoral girdle myology
of eosauropterygians. Information derived from the extant phylogenetic
bracket method was not sufficient to clarify muscle attachments in the
pectoral girdle of plesiosaurians. To correctly infer muscle
homologies, the extant phylogenetic bracket information had to be
complemented with developmental and osteological information, and
osteological transformations had to be traced back to Permian basal
neodiapsids. The reconstructed pectoral girdle musculature presented
here is, thus, significantly different from previous attempts. As in
secondarily-adapted aquatic modern analogues, several muscles
atrophied (e.g., pectoralis, episternocleidomastoideus) and others
specialized (e.g., coracobrachialis, clavodeltoideus) in order to
attain a more influential role to the stringent conditions of
subaquatic locomotion. The subcoracoscapularis, scapulodeltoideus,
scapulohumeralis and supracoracoideus are inferred to be glenohumeral
stabilizers. The clavodeltoideus acted as the main protractor muscle
and the coracobrachialis as a major retractor muscle, possibly in
conjunction with the latissimus dorsi. Several heads of the triceps
possibly atrophied, as in whales, serving mainly as a cubital joint
stabilizer. The trapezius, serratus and levator scapulae served as
pectoral girdle stabilizers.
Michael J. Benton, Philip C. J. Donoghue, Robert J. Asher, Matt
Friedman, Thomas J. Near, and Jakob Vinther (2015)
Constraints on the timescale of animal evolutionary history.
Palaeontologia Electronica 18.1.1FC; 1-106;
Dating the tree of life is a core endeavor in evolutionary biology.
Rates of evolution are fundamental to nearly every evolutionary model
and process. Rates need dates. There is much debate on the most
appropriate and reasonable ways in which to date the tree of life, and
recent work has highlighted some confusions and complexities that can
be avoided. Whether phylogenetic trees are dated after they have been
established, or as part of the process of tree finding, practitioners
need to know which calibrations to use. We emphasize the importance of
identifying crown (not stem) fossils, levels of confidence in their
attribution to the crown, current chronostratigraphic precision, the
primacy of the host geological formation and asymmetric confidence
intervals. Here we present calibrations for 88 key nodes across the
phylogeny of animals, ranging from the root of Metazoa to the last
common ancestor of Homo sapiens. Close attention to detail is
constantly required: for example, the classic bird-mammal date (base
of crown Amniota) has often been given as 310-315 Ma; the 2014
international time scale indicates a minimum age of 318 Ma.
Yanhong Pan, Franz T. Fürsich, Jiangyong Zhang, Yaqiong Wang and
Xiaoting Zheng (2015)
Biostratinomic analysis of Lycoptera beds from the Early Cretaceous
Yixian Formation, western Liaoning, China.
Palaeontology (advance online publication)
Little is known about the palaeoenvironments of the Early Cretaceous
lakes of western Liaoning. Uncertainties exist especially about the
water depth, water temperatures and annual temperature fluctuations.
Here, we analyse the preservation of the most abundant fish of the
lakes, the teleost Lycoptera, articulated skeletons of which occur in
large concentrations suggestive of mass mortality. Taphonomic features
such as degree of disarticulation, orientation patterns and
displacement of skeletal elements reveal distinct preservational
patterns. They suggest that the water temperature was low during
winter and exhibited pronounced seasonal fluctuations. The depth of
the lakes was not deep. Possible causes of the fish mortality are
discussed, of which anoxia is favoured. This leads to a more refined
palaeoenvironmental model for these palaeolakes, which harbour one of
the most important Mesozoic Lagerstätten.
Daniela E. Olivera, Ana M. Zavattieri & Mirta E. Quattrocchio (2015)
The palynology of the Cañadón Asfalto Formation (Jurassic), Cerro
Cóndor depocentre, Cañadón Asfalto Basin, Patagonia, Argentina:
palaeoecology and palaeoclimate based on ecogroup analysis.
Palynology (advance online publication)
The Cañadón Asfalto Formation, Cañadón Asfalto Basin, Patagonia,
Argentina, is interpreted as fluvial-lacustrine deposits. A
palynological study of the lower and middle parts of the unit, at the
Cañadón Lahuincó and Cañadón Caracoles sections, Cerro Cóndor
Depocentre Chubut province, northwestern Patagonia, Argentina is
presented. The quantitative composition of the palynofloras is
characterised by the dominance of pollen produced by the conifer
families Cheirolepidiaceae (Classopollis) and Araucariaceae (mainly
Araucariacites and Callialasporites), suggesting that warm-temperate
and relatively humid conditions under highly seasonal climate
prevailed during the depositional times of the unit. The abundance of
Botryococcus supports the presence of a shallow lake with probably
saline conditions. Five palynomorph ecogroups (PEGs) were recognised:
upland, lowland, riverside, coastal lake and aquatic. The ecological
requirements of the different plant families forming the PEGs enable
the inference of a sub-tropical palaeoclimate for the Cañadón Asfalto
region during late Early Jurassic to mid Middle Jurassic, which is
consistent with the ‘seasonally dry (winterwet)’ biome.
New Issue of Acta Palaeontologica Polonica 60 (1) 2015
A number of these papers that were posted in earlier MS form on the
DML, now official:
David J. Varricchio and Daniel E. Barta
Revisiting Sabath's "Larger Avian Eggs" from the Gobi Cretaceous.
Acta Palaeontologica Polonica 60 (1), 2015: 11-25
Terry A. Gates, Lindsay E. Zanno, and Peter J. Makovicky (2015)
Theropod teeth from the upper Maastrichtian Hell Creek Formation “Sue”
Quarry: New morphotypes and faunal comparisons.
Acta Palaeontologica Polonica 60 (1), 2015: 131-139
Lida Xing, Tetsuto Miyashita, Philip J. Currie, Hailu You, Jianping
Zhang, and Zhiming Dong (2015)
A new basal eusauropod from the Middle Jurassic of Yunnan, China, and
faunal compositions and transitions of Asian sauropodomorph dinosaurs.
Acta Palaeontologica Polonica 60 (1), 2015: 145-154
Igor G. Danilov, Natasha S. Vitek, Alexander O. Averianov, and Vadim
N. Glinskiy (2015)
A new soft-shelled trionychid turtle of the genus Khunnuchelys from
the Upper Cretaceous Bostobe Formation of Kazakhstan.
Acta Palaeontologica Polonica 60 (1), 2015: 155-161
Bruce M. Rothschild and Virginia Naples (2015)
Decompression syndrome and diving behavior in Odontochelys, the first turtle.
Acta Palaeontologica Polonica 60 (1), 2015: 163-167
Jocelyn Falconnet (2015)
The sphenacodontid synapsid Neosaurus cynodus, and related material,
from the Permo-Carboniferous of France.
Acta Palaeontologica Polonica 60 (1), 2015: 169-182
Ariana Paulina-Carabajal and Cecilia Succar (2015)
The endocranial morphology and inner ear of the abelisaurid theropod
Acta Palaeontologica Polonica 60 (1), 2015: 141-144