scholarly journals Inner ear biomechanics reveals Late Triassic origin of mammalian endothermy

2021 ◽  
Author(s):  
Ricardo Araujo ◽  
Romain David ◽  
Julien Benoit ◽  
Lungmus Jacqueline ◽  
Fred Spoor ◽  
...  
Keyword(s):  
Inner Ear ◽  
Cross Sections ◽  
Motor Coordination ◽  
Morphological Changes ◽  
Physiological Characteristic ◽  
Late Triassic ◽  
New Information ◽  
Ecological Dominance ◽  
Semicircular Ducts ◽  
Head Rotations

Abstract Endothermy (“warm-bloodedness”) underpins the ecological dominance of mammals and birds in diverse environmental settings1-3. However, it is unclear when this crucial feature emerged during mammalian evolutionary history, as most fossil evidence is ambiguous4-25. Here, we show that new information on this key evolutionary transition can be obtained from the morphology of the endolymph-filled semicircular ducts of the inner ear that monitor head rotations and are essential for motor coordination, navigation, and spatial awareness26-31. Increased body temperature during the ectotherm–endotherm transition of mammal ancestors would decrease endolymph viscosity, negatively impacting the biomechanics of the semicircular ducts32,33, while simultaneously increasing activity levels34,35 required improved performance36. Specific morphological changes to the membranous ducts and enclosing bony canals were, therefore, necessary to maintain optimal functionality. We track these morphological changes in 341 vertebrates, including 56 extinct synapsids, and show that canals with relatively thin cross-sections and small radii of curvature are indicative of mammalian endothermy. This inner ear morphotype evolved abruptly ~233 million years ago, during the Late Triassic, in Mammaliamorpha. Our conclusion differs from previous suggestions3-17, and we interpret most stem-mammals as ectotherms. Endothermy as a crucial physiological characteristic joins other distinctive mammalian features that arose during this period of climatic instability37-39.

Morphological changes of nanofiber cross-sections due to surface tension

2021 ◽  
Vol 44 ◽  
pp. 101211
Author(s):  
Shuang Wang ◽  
Xiying Li ◽  
Xin Yi ◽  
Huiling Duan
Keyword(s):  
Surface Tension ◽  
Cross Sections ◽  
Morphological Changes

3D modelling of the flow distribution in the delta of Lake Øyeren, Norway

2010 ◽  
Vol 41 (2) ◽  
pp. 92-103 ◽  
Author(s):  
Peggy Zinke ◽  
Nils Reidar Bøe Olsen ◽  
Jim Bogen ◽  
Nils Rüther
Keyword(s):  
Water Level ◽  
Cross Sections ◽  
Stokes Equations ◽  
Morphological Changes ◽  
Flow Distribution ◽  
Field Measurements ◽  
Navier Stokes ◽  
Error Sources ◽  
Navier Stokes Equations ◽  
Water Level Measurements

A 3D numerical model was used to compute the discharge distribution in the channel branches of Lake Øyeren's delta in Norway. The model solved the Navier–Stokes equations with the k–ɛ turbulence model on a 3D unstructured grid. The bathymetry dataset for the modelling had to be combined from different data sources. The results for three different flow situations in 1996 and 1997 showed a relative accuracy of the computed discharges within the range of 0 to±20% compared with field measurements taken by an ADCP at 13 cross sections of the distributary channels. The factors introducing the most error in the computed results are believed to be uncertainties concerning the bathymetry. A comparison between the computational results of the older morphology data from 1985–1990 and the model morphology from 1995–2004 indicated that morphological changes in this period had already had consequences for the flow distribution in some channels. Other important error sources were the inevitable use of averaged water level gradients because of unavailable water level measurements within the delta.

Field-Emission Scanning Electron Microscopy and Energy-Dispersive X-Ray Analysis to Understand the Role of Tannin-Based Dyes in the Degradation of Historical Wool Textiles

2014 ◽  
Vol 20 (5) ◽  
pp. 1534-1543 ◽  
Author(s):  
Annalaura Restivo ◽  
Ilaria Degano ◽  
Erika Ribechini ◽  
Josefina Pérez-Arantegui ◽  
Maria Perla Colombini
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Elemental Composition ◽  
Field Emission ◽  
Cross Sections ◽  
Morphological Changes ◽  
Energy Dispersive ◽  
X Ray ◽  
Edx Analysis ◽  
Scanning Electron

Abstract:An innovative approach, combining field-emission scanning electron microscopy (FESEM) with energy dispersive X-ray spectroscopy (EDX) analysis, is presented to investigate the degradation mechanisms affecting tannin-dyed wool. In fact, tannin-dyed textiles are more sensitive to degradation then those dyed with other dyestuffs, even in the same conservation conditions.FESEM-EDX was first used to study a set of 48 wool specimens (artificially aged) dyed with several raw materials and mordants, and prepared according to historical dyeing recipes. EDX analysis was performed on the surface of wool threads and on their cross-sections. In addition, in order to validate the model formulated by the analysis of reference materials, several samples collected from historical and archaeological textiles were subjected to FESEM-EDX analysis.FESEM-EDX investigations enabled us to reveal the correlation between elemental composition and morphological changes. In addition, aging processes were clarified by studying changes in the elemental composition of wool from the protective cuticle to the fiber core in cross-sections. Morphological and elemental analysis of wool specimens and of archaeological and historical textiles showed that the presence of tannins increases wool damage, primarily by causing a sulfur decrease and fiber oxidation.

scholarly journals Endocast of the Late Triassic (Carnian) dinosaur Saturnalia tupiniquim: implications for the evolution of brain tissue in Sauropodomorpha

2018 ◽  
Author(s):  
Mario Bronzati ◽  
Oliver W M Rauhut ◽  
Jonathas S Bittencourt ◽  
Max C. Langer
Keyword(s):  
South America ◽  
Brain Tissue ◽  
Evolutionary History ◽  
Morphological Changes ◽  
Volume Reduction ◽  
Late Triassic ◽  
History Of

The evolutionary history of dinosaurs might date back to the fist stages of the Triassic (c. 250– 240 Ma), but the oldest unequivocal records of the group come from Late Triassic (Carnian – c. 230 Ma) rocks of South America. Here, we present the fist braincase endocast of a Carnian dinosaur, the sauropodomorph Saturnalia tupiniquim, and provide new data regarding the evolution of the flccular and paraflccular lobe of the cerebellum (FFL), which has been extensively discussed in the fild of palaeoneurology. Previous studies proposed that the development of a permanent quadrupedal stance was one of the factors leading to the volume reduction of the FFL of sauropods. However, based on the new data for S. tupiniquim we identifid a fist moment of FFL volume reduction in nonsauropodan Sauropodomorpha, preceding the acquisition of a fully quadrupedal stance. Analysing variations in FFL volume alongside other morphological changes in the group, we suggest that this reduction is potentially related to the adoption of a more restricted herbivore diet. In this context, the FFL of sauropods might represent a vestigial trait, retained in a reduced version from the bipedal and predatory early sauropodomorphs.

Morphological changes in the inner ear induced by bacterial endotoxin

1995 ◽  
Vol 28 (2) ◽  
pp. 80-87 ◽  
Author(s):  
Kensuke Watanabe ◽  
Nagae Naito ◽  
Yasuo Tanaka
Keyword(s):  
Inner Ear ◽  
Morphological Changes ◽  
Bacterial Endotoxin

A newly discovered skull of the temnospondyl amphibian Dendrerpeton acadianum Owen

1987 ◽  
Vol 24 (4) ◽  
pp. 796-805 ◽  
Author(s):  
Stephen J. Godfrey ◽  
Anthony R. Fiorillo ◽  
Robert L. Carroll
Keyword(s):  
Inner Ear ◽  
Posterior Margin ◽  
Functional Relationship ◽  
Impedance Matching ◽  
Three Dimensional ◽  
Natural Position ◽  
Lower Jaw ◽  
New Information ◽  
Early Tetrapods ◽  
Supporting Element

A virtually complete three-dimensional skull of a subadult of the temnospondyl amphibian Dendrerpeton acadianum provides new information on the structure of the palate and lower jaw. The left stapes appears to lie in a natural position on the quadrate ramus of the pterygoid. The proportionately large otic ossicle probably precluded it from having acted as a transmitter of airborne vibrations from a tympanum to the inner ear. The use of the term "otic notch" should be restricted to amphibians or reptiles in which the embayment of the posterior margin of the cheek is accompanied by the presence of a slender rod-like stapes that could have functioned as part of an impedance matching system. In those species in which a notch is present but the stapes is a massive "supporting" element, the term "squamosal embayment" should be used, rather than "otic notch." The squamosal embayment in early tetrapods may have been inherited directly from their fish ancestors and had no functional relationship to hearing.

scholarly journals Using a laser measurement system for monitoring morphological changes on the Strug rock fall, Slovenia

2005 ◽  
Vol 5 (1) ◽  
pp. 143-153 ◽  
Author(s):  
M. Mikoš ◽  
A. Vidmar ◽  
M. Brilly
Keyword(s):  
Fixed Points ◽  
Cross Sections ◽  
Measurement System ◽  
High Performance ◽  
Morphological Changes ◽  
Ground Surface ◽  
Rock Fall ◽  
Laser Measurement ◽  
Laser Measurement System ◽  
Surface Changes

Abstract. A medium-ranged high performance handheld reflectorless laser measurement system, was used for a morphological survey on the Strug rock fall in W Slovenia in the period from August 2003 to August 2004. The purpose was to evaluate its potential for monitoring ground surface changes in rock fall source areas and to help evaluating morphological changes by measuring distance from fixed points. In the area, 21 fixed geodetic points have been established. Altogether, seven measurement sets with more than 5500 points have been gathered in the rock fall area. Choosing a point cloud with a density of less than 1 point per 10m2 on a very rough rock fall surface failed to be a good solution. The changes on larger areas were shown by displacements of selected significantly large-sized rock blocks with a volume of several m3. Because only smaller changes were observed between the single field series, the rock fall surface generally remained unchanged. Local surface changes of the order of 1 m or more, were clearly shown by measurements in the selected referenced cross sections. The usage of these cross sections gave a possibility to evaluate volumetric changes on the surface. The laser measurement system provided a good replacement for the classical terrestrial geodetic survey equipment, especially when performing remote monitoring of morphological changes in rock fall hazard zones, however, the case is different when fixed points are to be measured precisely.

scholarly journals LOCALIZATION OF MACROMOLECULES IN ESCHERICHIA COLI

1961 ◽  
Vol 9 (3) ◽  
pp. 539-553 ◽  
Author(s):  
Lucien G. Caro
Keyword(s):  
Escherichia Coli ◽  
Poisson Distribution ◽  
Cross Sections ◽  
Morphological Changes ◽  
Nuclear Region ◽  
High Concentration ◽  
Short Pulses ◽  
Thin Sections ◽  
Change Concerns ◽  
Very Short Pulses

If thin sections of Escherichia coli, labeled uniformly with tritium, are radioautographed calculations, based on the distribution of section sizes show that the number of H3 decays per section should be very close to a Poisson distribution. We might, therefore, expect that the distribution of radioautographic grain counts among random cross-sections should follow a Poisson distribution. It can then be inferred that a deviation from a Poisson indicates a high concentration of label in a preferred region. This region can then be identified by analysis of serial section and comparison with electron micrographs. Sections of cells labeled with leucine-H3 gave a Poisson distribution of grain counts, and it was concluded that proteins were distributed fairly uniformly throughout the cell. The situation was not changed if labeled cells were placed in chloramphenicol or if very short pulses of label were used. When Escherichia coli is grown in presence of chloramphenicol a major morphological change concerns the nuclear region: it becomes more regular in outline, nearly spherical, and occupies a smaller proportion of the cell length. The previously described association between DNA labeled with thymidine-H3 and the nuclear region was confirmed by showing that the distribution of the label in the cell followed exactly the morphological changes of the nuclear region. It was also shown that the concentration of DNA in the nuclear region was at least 45 times higher than that of the cytoplasm. Several morphological features of cells grown in chloramphenicol and examined in the electron microscope are discussed.

scholarly journals Gata2 is required for the development of inner ear semicircular ducts and the surrounding perilymphatic space

2010 ◽  
Vol 239 (9) ◽  
pp. 2452-2469 ◽  
Author(s):  
Maarja Haugas ◽  
Kersti Lilleväli ◽  
Janne Hakanen ◽  
Marjo Salminen
Keyword(s):  
Inner Ear ◽  
Semicircular Ducts ◽  
Perilymphatic Space
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