scholarly journals Wing musculature reconstruction in extinct flightless auks (Pinguinus and Mancalla) reveals incomplete convergence with penguins (Spheniscidae) due to differing ancestral states

2020 ◽  
Author(s):  
Junya Watanabe ◽  
Daniel J Field ◽  
Hiroshige Matsuoka
Keyword(s):  
Convergent Evolution ◽  
Functional Anatomy ◽  
Skeletal Remains ◽  
Phenotypic Evolution ◽  
Crown Group ◽  
Mechanical Advantage ◽  
Anatomical Data ◽  
The Face ◽  
Ancestral States ◽  
Close Relatives

Abstract Despite longstanding interest in convergent evolution, factors that result in deviations from fully convergent phenotypes remain poorly understood. In birds, the evolution of flightless wing-propelled diving has emerged as a classic example of convergence, having arisen in disparate lineages including penguins (Sphenisciformes) and auks (Pan-Alcidae, Charadriiformes). Nevertheless, little is known about the functional anatomy of the wings of flightless auks because all such taxa are extinct, and their morphology is almost exclusively represented by skeletal remains. Here, in order to re-evaluate the extent of evolutionary convergence among flightless wing-propelled divers, wing muscles and ligaments were reconstructed in two extinct flightless auks, representing independent transitions to flightlessness: Pinguinus impennis (a crown-group alcid), and Mancalla (a stem-group alcid). Extensive anatomical data were gathered from dissections of 12 species of extant charadriiforms and 4 aequornithine waterbirds including a penguin. The results suggest that the wings of both flightless auk taxa were characterized by an increased mechanical advantage of wing elevator/retractor muscles, and decreased mobility of distal wing joints, both of which are likely advantageous for wing-propelled diving and parallel similar functional specializations in penguins. However, the conformations of individual muscles and ligaments underlying these specializations differ markedly between penguins and flightless auks, instead resembling those in each respective group’s close relatives. Thus, the wings of these flightless wing-propelled divers can be described as convergent as overall functional units, but are incompletely convergent at lower levels of anatomical organization—a result of retaining differing conditions from each group’s respective volant ancestors. Detailed investigations such as this one may indicate that, even in the face of similar functional demands, courses of phenotypic evolution are dictated to an important degree by ancestral starting points.

scholarly journals Wing musculature reconstruction in extinct flightless auks (Pinguinus and Mancalla) reveals incomplete convergence with penguins (Spheniscidae) due to differing ancestral states

2020 ◽  
Author(s):  
Junya Watanabe ◽  
Daniel J. Field ◽  
Hiroshige Matsuoka
Keyword(s):  
Convergent Evolution ◽  
Functional Anatomy ◽  
Skeletal Remains ◽  
Phenotypic Evolution ◽  
Crown Group ◽  
Mechanical Advantage ◽  
Anatomical Data ◽  
The Face ◽  
Ancestral States ◽  
Close Relatives

AbstractDespite longstanding interest in convergent evolution, factors that result in deviations from fully convergent phenotypes remain poorly understood. In birds, the evolution of flightless wing-propelled diving has emerged as a classic example of convergence, having arisen in disparate lineages including penguins (Sphenisciformes) and auks (Pan-Alcidae, Charadriiformes). Nevertheless, little is known about the functional anatomy of the wings of flightless auks because all such taxa are extinct, and their morphology is almost exclusively represented by skeletal remains. Here, in order to re-evaluate the extent of evolutionary convergence among flightless wing-propelled divers, wing muscles and ligaments were reconstructed in two extinct flightless auks, representing independent transitions to flightlessness: Pinguinus impennis (a crown-group alcid), and Mancalla (a stem-group alcid). Extensive anatomical data were gathered from dissections of 12 species of extant charadriiforms and 4 aequornithine waterbirds including a penguin. It was found that the wings of both flightless auk taxa were characterized by an increased mechanical advantage of wing elevator/retractor muscles, and decreased mobility of distal wing joints, both of which are likely advantageous for wing-propelled diving and parallel similar functional specializations in penguins. However, the conformations of individual muscles and ligaments underlying these specializations differ markedly between penguins and flightless auks, instead resembling those in each respective group’s close relatives. Thus, the wings of these flightless wing-propelled divers can be described as convergent as overall functional units, but are incompletely convergent at lower levels of anatomical organization—a result of retaining differing conditions from each group’s respective volant ancestors. Detailed investigations such as this one may indicate that, even in the face of similar functional demands, courses of phenotypic evolution are dictated to an important degree by ancestral starting points.

The Difference in Facial Movement Between the Medial and the Lateral Midface: A 3D Skin Surface Vector Analysis

2021 ◽  
Author(s):  
David L Freytag ◽  
Michael G Alfertshofer ◽  
Konstantin Frank ◽  
Dmitry V Melnikov ◽  
Nicholas Moellhoff ◽  
...  
Keyword(s):  
3D Imaging ◽  
Functional Anatomy ◽  
Skin Surface ◽  
Facial Movements ◽  
Anatomic Location ◽  
Objective Evidence ◽  
The Face ◽  
Functional Boundary ◽  
The Mean ◽  
The Difference

Abstract Background Our understanding of the functional anatomy of the face is constantly improving. To date, it is unclear whether the anatomic location of the line of ligaments has any functional importance during normal facial movements such as smiling. Objectives It is the objective of the present study to identify differences in facial movements between the medial and lateral midface by means of skin vector displacement analyses derived from 3D imaging and to further ascertain whether the line of ligaments has both a structural and functional significance in these movements. Methods The study sample consisted of 21 healthy volunteers (9 females & 12 males) of Caucasian ethnic background with a mean age of 30.6 (8.3) years and a mean BMI of 22.57 (2.5) kg/m 2. 3D images of the volunteers’ faces in repose and during smiling (Duchenne type) were taken. 3D imaging-based skin vector displacement analyses were conducted. Results The mean horizontal skin displacement was 0.08 (2.0) mm in the medial midface (lateral movement) and was -0.08 (1.96) mm in the lateral midface (medial movement) (p = 0.711). The mean vertical skin displacement (cranial movement of skin toward the forehead/temple) was 6.68 (2.4) mm in the medial midface whereas it was 5.20 (2.07) mm in the lateral midface (p = 0.003). Conclusions The results of this study provide objective evidence for an antagonistic skin movement between the medial and the lateral midface. The functional boundary identified by 3D imaging corresponds to the anatomic location of the line of ligaments.

scholarly journals The early elasmobranch Phoebodus : phylogenetic relationships, ecomorphology and a new time-scale for shark evolution

2019 ◽  
Vol 286 (1912) ◽  
pp. 20191336 ◽  
Author(s):  
Linda Frey ◽  
Michael Coates ◽  
Michał Ginter ◽  
Vachik Hairapetian ◽  
Martin Rücklin ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Time Scale ◽  
Body Shape ◽  
Skeletal Remains ◽  
Late Devonian ◽  
Crown Group ◽  
Anatomical Knowledge ◽  
Close Relationship ◽  
Stem Lineage ◽  
Fin Spines

Anatomical knowledge of early chondrichthyans and estimates of their phylogeny are improving, but many taxa are still known only from microremains. The nearly cosmopolitan and regionally abundant Devonian genus Phoebodus has long been known solely from isolated teeth and fin spines. Here, we report the first skeletal remains of Phoebodus from the Famennian (Late Devonian) of the Maïder region of Morocco, revealing an anguilliform body, specialized braincase, hyoid arch, elongate jaws and rostrum, complementing its characteristic dentition and ctenacanth fin spines preceding both dorsal fins. Several of these features corroborate a likely close relationship with the Carboniferous species Thrinacodus gracia , and phylogenetic analysis places both taxa securely as members of the elasmobranch stem lineage. Identified as such, phoebodont teeth provide a plausible marker for range extension of the elasmobranchs into the Middle Devonian, thus providing a new minimum date for the origin of the chondrichthyan crown-group. Among pre-Carboniferous jawed vertebrates, the anguilliform body shape of Phoebodus is unprecedented, and its specialized anatomy is, in several respects, most easily compared with the modern frilled shark Chlamydoselachus . These results add greatly to the morphological, and by implication ecological, disparity of the earliest elasmobranchs.

scholarly journals PHOTOGRAMMETRIC NETWORK FOR EVALUATION OF HUMAN FACES FOR FACE RECONSTRUCTION PURPOSE

2012 ◽  
Vol XXXIX-B3 ◽  
pp. 549-552
Author(s):  
P. Schrott ◽  
Á. Detrekői ◽  
K. Fekete
Keyword(s):  
Research Group ◽  
Skeletal Remains ◽  
Ct Scans ◽  
Large Dataset ◽  
Reconstruction Process ◽  
Face Reconstruction ◽  
3D Data ◽  
The Face ◽  
Archaeological Sciences ◽  
Human Faces

Facial reconstruction is the process of reconstructing the geometry of faces of persons from skeletal remains. A research group (<i>BME Cooperation Research Center for Biomechanics</i>) was formed representing several organisations to combine knowledgebases of different disciplines like anthropology, medical, mechanical, archaeological sciences etc. to computerize the face reconstruction process based on a large dataset of 3D face and skull models gathered from living persons: cranial data from CT scans and face models from photogrammetric evaluations. The BUTE Dept. of Photogrammetry and Geoinformatics works on the method and technology of the 3D data acquisition for the face models. In this paper we will present the research and results of the photogrammetric network design, the modelling to deal with visibility constraints, and the investigation of the developed basic photogrammetric configuration to specify the result characteristics to be expected using the device built for the photogrammetric face measurements.

scholarly journals Low effective mechanical advantage of giraffes’ limbs during walking reveals trade-off between limb length and locomotor performance

2021 ◽  
Author(s):  
Christopher Basu ◽  
John R. Hutchinson
Keyword(s):  
Body Mass ◽  
Inverse Dynamics ◽  
Limb Length ◽  
Segment Length ◽  
Mechanical Advantage ◽  
Walking Gait ◽  
Moment Arms ◽  
Athletic Ability ◽  
Close Relatives ◽  
Similar Body

AbstractGiraffes (Giraffa camelopardalis) possess specialised locomotor morphology, namely elongate and gracile distal limbs. Whilst this contributes to their overall height (and enhanced feeding behaviour), we propose that the combination of long limb segments and modest muscle lever arms results in low effective mechanical advantage (EMA, the ratio of in-lever to out-lever moment arms), when compared with other cursorial mammals. To test this, we used a combination of experimentally measured kinematics and ground rection forces (GRFs), musculoskeletal modelling, and inverse dynamics to calculate giraffe forelimb EMA during walking. Giraffes walk with an EMA of 0.34 (±0.05 S.D.), with no evident association with speed within their walking gait. Giraffe EMA was markedly below the expectations extrapolated from other mammals ranging from 0.03 – 297 kg, and provides further evidence that EMA plateaus or even diminishes in mammals exceeding horse size. We further tested the idea that limb segment length is a factor which determines EMA, by modelling the GRF and muscle moment arms in the extinct giraffid Sivatherium giganteum and the other extant giraffid Okapia johnstoni. Giraffa and Okapia shared similar EMA, despite a 4-6 fold difference in body mass (Okapia EMA = 0.38). In contrast Sivatherium, sharing a similar body mass to Giraffa, had greater EMA (0.59), which we propose reflects behavioural differences, such athletic performance. Our modelling approach suggests that limb length is a determinant of GRF moment arm magnitude, and that unless muscle moment arms scale isometrically with limb length, tall mammals are prone to low EMA.Significance StatementGiraffes are the tallest living animals - using their height to access food unavailable to their competitors. It is not clear how their specialized anatomy impacts their athletic ability. We made musculoskeletal models of the forelimbs from a giraffe and two close relatives, and used motion-capture and forceplate data to measure how efficient they are when walking in a straight line. A horse for example, uses just 1 unit of muscle force to oppose 1 unit of force on the ground. Giraffe limbs however are comparatively disadvantaged – their muscles must develop 3 units of force to oppose 1 unit of force at the ground. This explains why giraffes walk and run at relatively slow speeds.

scholarly journals The Functional Anatomy of the Superficial Fat Compartments of the Face

2018 ◽  
Vol 141 (6) ◽  
pp. 1351-1359 ◽  
Author(s):  
Thilo L. Schenck ◽  
Konstantin C. Koban ◽  
Alexander Schlattau ◽  
Konstantin Frank ◽  
Jonathan M. Sykes ◽  
...  
Keyword(s):  
Functional Anatomy ◽  
The Face

scholarly journals Biased Gene Retention in the Face of Introgression Obscures Species Relationships

2020 ◽  
Vol 12 (9) ◽  
pp. 1646-1663 ◽  
Author(s):  
Evan S Forsythe ◽  
Andrew D L Nelson ◽  
Mark A Beilstein
Keyword(s):  
Statistical Tests ◽  
Nuclear Genome ◽  
Introgressive Hybridization ◽  
Species Relationships ◽  
Genome Composition ◽  
Haplotype Blocks ◽  
Gene Retention ◽  
The Face ◽  
Phylogenomic Analyses ◽  
Close Relatives

Abstract Phylogenomic analyses are recovering previously hidden histories of hybridization, revealing the genomic consequences of these events on the architecture of extant genomes. We applied phylogenomic techniques and several complementary statistical tests to show that introgressive hybridization appears to have occurred between close relatives of Arabidopsis, resulting in cytonuclear discordance and impacting our understanding of species relationships in the group. The composition of introgressed and retained genes indicates that selection against incompatible cytonuclear and nuclear–nuclear interactions likely acted during introgression, whereas linkage also contributed to genome composition through the retention of ancient haplotype blocks. We also applied divergence-based tests to determine the species branching order and distinguish donor from recipient lineages. Surprisingly, these analyses suggest that cytonuclear discordance arose via extensive nuclear, rather than cytoplasmic, introgression. If true, this would mean that most of the nuclear genome was displaced during introgression whereas only a small proportion of native alleles were retained.

scholarly journals A novel unbiased test for molecular convergent evolution and discoveries in echolocating, aquatic and high-altitude mammals

2017 ◽  
Author(s):  
Amir Marcovitz ◽  
Yatish Turakhia ◽  
Michael Gloudemans ◽  
Benjamin A. Braun ◽  
Heidi I. Chen ◽  
...  
Keyword(s):  
Amino Acid ◽  
High Altitude ◽  
Convergent Evolution ◽  
Amino Acid Substitutions ◽  
Phenotypic Evolution ◽  
Protein Coding ◽  
Unbiased Test ◽  
Subterranean Mammals ◽  
Molecular Convergence ◽  
Physiological Characters

AbstractDistantly related species entering similar biological niches often adapt by evolving similar morphological and physiological characters. The extent to which genomic molecular convergence, and the extent to which coding mutations underlie this convergent phenotypic evolution remain unknown. Using a novel test, we ask which group of functionally coherent genes is most affected by convergent amino acid substitutions between phenotypically convergent lineages. This most affected sets reveals 75 novel coding convergences in important genes that pattern a highly adapted organ: the cochlea, skin and lung in echolocating, aquatic and high-altitude mammals, respectively. Our test explicitly requires the enriched converged term to not be simultaneously enriched for divergent mutations, and correctly dismisses relaxation-based signals, such as those produced by vision genes in subterranean mammals. This novel test can be readily applied to birds, fish, flies, worms etc., to discover more of the fascinating contribution of protein coding convergence to phenotype convergence.

Crinoid respiration and the distribution of energetic strategies among marine invertebrates

2019 ◽  
Author(s):  
James Saulsbury
Keyword(s):  
Marine Invertebrates ◽  
Functional Anatomy ◽  
Circulatory System ◽  
Geological Time ◽  
Success Story ◽  
Positive Allometry ◽  
Marine Predators ◽  
The Face ◽  
Stalked Crinoids

AbstractDuring the Mesozoic, the radiation of durophagous marine predators caused the ecological and evolutionary diminution of once-successful groups, including stalked, suspension-feeding echinoderms known as crinoids. Featherstars, crinoids that shed the stalk during development and exhibit anti-predatory adaptations such as high motility, defied this trend, and today they are widespread and diverse across ocean depths. As a ‘success story’ of the Mesozoic Marine Revolution, featherstars could be used to reveal how some marine lineages succeeded in the face of increased predation over geological time. However, current limited understanding of crinoid functional anatomy has inhibited such study. Using microphotography, scanning electron microscopy and computed tomography, I characterize the structure and variation of crinoid circulatory anatomy and explore differences between featherstars and stalked forms. Contrary to previous accounts, I find support for the role of coelomic circulation in crinoid respiration. This includes a previously undocumented case of positive allometry: larger crinoids have more complex circulatory anatomy. Moreover, quantitative analysis of coelomic anatomy shows that the circulatory system is generally more complex in featherstars than in stalked crinoids. The adaptations that allowed featherstars to persist in shallow water apparently entailed an increase in the functional capacity of the circulatory system, possibly due to consistently greater metabolic rates.

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