Functional and biomechanic aspects of the scapular girdle and forelimbs of Unaysaurus tolentinoi Leal et al., 2004 (Saurischia: Sauropodomorpha)

Vargas-Peixoto, Dilson; Da-Rosa, Átila Augusto Stock; França, Marco Aurélio Gallo de

doi:10.1016/j.jsames.2014.09.024

Cited by 5 publications

(6 citation statements)

References 37 publications

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“…Full elbow extension (0°) was only allowed (indeed, required) in the reference pose ( Table S3 ), whereas maximal extension in the resting pose was 15–20° for both taxa, avoiding full extension of the elbow. These limits on elbow extension are similar to those found for the basal tetrapod Ichthyostega ( Pierce, Clack & Hutchinson, 2012 ), the crocodylian Alligator ( Hutson & Hutson, 2012 ; Baier & Gatesy, 2013 ), basal saurischians ( Sereno, 1993 ), quadrupedal ornithischians ( Maidment & Barrett, 2012 ), basal sauropodomorphs ( Bonnan & Senter, 2007 ; Mallison, 2010b ; Vargas-Peixoto, Da-Rosa & Franca, 2015 ), non-avian theropods ( Senter & Robins, 2005 ; White et al, 2015 ) and birds ( Baier, Gatesy & Dial, 2013 ). Thus our models reject the inference that Mussaurus would have routinely used a fully columnar forelimb pose.…”

Section: Discussionsupporting

confidence: 77%

“…Thus our models reject the inference that Mussaurus would have routinely used a fully columnar forelimb pose. This inference also supports the conclusion that no matter if manipulation is being done with fleshed ( Hutson & Hutson, 2012 ) or skeletonized material ( Sereno, 1993 ; Senter & Robins, 2005 ; Bonnan & Senter, 2007 ; Mallison, 2010b ; Pierce, Clack & Hutchinson, 2012 ; Vargas-Peixoto, Da-Rosa & Franca, 2015 ; White et al, 2015 ), elbow hyperextension close to 180° leads to a high risk of disarticulation. Similarly, maximal elbow flexion was 110–130° in the two taxa (regardless of resting or reference pose), so the total ROM was less in the resting pose vs. the reference pose.…”

Section: Discussionsupporting

confidence: 71%

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Forelimb muscle and joint actions in Archosauria: insights fromCrocodylus johnstoni(Pseudosuchia) andMussaurus patagonicus(Sauropodomorpha)

Otero

Allen

Pol

et al. 2017

PeerJ

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Many of the major locomotor transitions during the evolution of Archosauria, the lineage including crocodiles and birds as well as extinct Dinosauria, were shifts from quadrupedalism to bipedalism (and vice versa). Those occurred within a continuum between more sprawling and erect modes of locomotion and involved drastic changes of limb anatomy and function in several lineages, including sauropodomorph dinosaurs. We present biomechanical computer models of two locomotor extremes within Archosauria in an analysis of joint ranges of motion and the moment arms of the major forelimb muscles in order to quantify biomechanical differences between more sprawling, pseudosuchian (represented the crocodile Crocodylus johnstoni) and more erect, dinosaurian (represented by the sauropodomorph Mussaurus patagonicus) modes of forelimb function. We compare these two locomotor extremes in terms of the reconstructed musculoskeletal anatomy, ranges of motion of the forelimb joints and the moment arm patterns of muscles across those ranges of joint motion. We reconstructed the three-dimensional paths of 30 muscles acting around the shoulder, elbow and wrist joints. We explicitly evaluate how forelimb joint mobility and muscle actions may have changed with postural and anatomical alterations from basal archosaurs to early sauropodomorphs. We thus evaluate in which ways forelimb posture was correlated with muscle leverage, and how such differences fit into a broader evolutionary context (i.e. transition from sprawling quadrupedalism to erect bipedalism and then shifting to graviportal quadrupedalism). Our analysis reveals major differences of muscle actions between the more sprawling and erect models at the shoulder joint. These differences are related not only to the articular surfaces but also to the orientation of the scapula, in which extension/flexion movements in Crocodylus (e.g. protraction of the humerus) correspond to elevation/depression in Mussaurus. Muscle action is highly influenced by limb posture, more so than morphology. Habitual quadrupedalism in Mussaurus is not supported by our analysis of joint range of motion, which indicates that glenohumeral protraction was severely restricted. Additionally, some active pronation of the manus may have been possible in Mussaurus, allowing semi-pronation by a rearranging of the whole antebrachium (not the radius against the ulna, as previously thought) via long-axis rotation at the elbow joint. However, the muscles acting around this joint to actively pronate it may have been too weak to drive or maintain such orientations as opposed to a neutral position in between pronation and supination. Regardless, the origin of quadrupedalism in Sauropoda is not only linked to manus pronation but also to multiple shifts of forelimb morphology, allowing greater flexion movements of the glenohumeral joint and a more columnar forelimb posture.

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Section: Discussionsupporting

confidence: 77%

Section: Discussionsupporting

confidence: 71%

Forelimb muscle and joint actions in Archosauria: insights fromCrocodylus johnstoni(Pseudosuchia) andMussaurus patagonicus(Sauropodomorpha)

Otero

Allen

Pol

et al. 2017

PeerJ

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“…It is noteworthy that the estimated resting pose of the elbow approximates maximum elbow flexion as found previously by range-of-motion studies in theropods with semilunate carpals [ 16 , 17 , 19 ], non-coelurosaurian theropods without semilunate carpals [ 17 , 18 ], and basal sauropodomorphs [ 20 , 81 ]. The estimated resting pose of the wrist also approximates maximum wrist flexion in theropods with semilunate carpals [ 16 , 17 , 19 ].…”

Section: Discussionsupporting

confidence: 68%

Resting Orientations of Dinosaur Scapulae and Forelimbs: A Numerical Analysis, with Implications for Reconstructions and Museum Mounts

Senter

Robins

2015

PLoS ONE

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The inclination of the scapular blade and the resting pose of the forelimb in dinosaurs differ among reconstructions and among skeletal mounts. For most dinosaurian taxa, no attempt has previously been made to quantify the correct resting positions of these elements. Here, we used data from skeletons preserved in articulation to quantify the resting orientations of the scapula and forelimb in dinosaurs. Specimens were included in the study only if they were preserved lying on their sides; for each specimen the angle between forelimb bones at a given joint was included in the analysis only if the joint was preserved in articulation. Using correlation analyses of the angles between the long axis of the sacrum, the first dorsal centrum, and the scapular blade in theropods and Eoraptor, we found that vertebral hyperextension does not influence scapular orientation in saurischians. Among examined taxa, the long axis of the scapular blade was found to be most horizontal in bipedal saurischians, most vertical in basal ornithopods, and intermediate in hadrosauroids. We found that in bipedal dinosaurs other than theropods with semilunate carpals, the resting orientation of the elbow is close to a right angle and the resting orientation of the wrist is such that the hand exhibits only slight ulnar deviation from the antebrachium. In theropods with semilunate carpals the elbow and wrist are more flexed at rest, with the elbow at a strongly acute angle and with the wrist approximately at a right angle. The results of our study have important implications for correct orientations of bones in reconstructions and skeletal mounts. Here, we provide recommendations on bone orientations based on our results.

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“…Full elbow extension (0°) was only allowed (indeed, required) in the reference pose (Table S3), whereas maximal extension in the resting pose was 15-20° for both taxa, avoiding full extension of the elbow. These limits on elbow extension are similar to those found for the basal tetrapod Ichthyostega (Pierce, Clack & Hutchinson, 2012), the crocodylian Alligator (Hutson & Hutson, 2012;, basal saurischians (Sereno, 1993), quadrupedal ornithischians (Maidment & Barrett, 2012), basal sauropodomorphs (Bonnan & Senter, 2007;Mallison, 2010b;Vargas-Peixoto, Da Rosa & Franca, 2015), non-avian theropods (Senter & Robins, 2005;White et al, 2015) and birds (Baier, Gatesy & Dial, 2013). Thus our PeerJ reviewing PDF | (2017:04:17707:1:1:CHECK 3 Oct 2017)…”

Section: Discussionsupporting

confidence: 79%

“…Manuscript to be reviewed models reject the inference that Mussaurus would have routinely used a fully columnar forelimb pose. This inference also supports the conclusion that no matter if manipulation is being done with fleshed (Hutson & Hutson, 2012) or skeletonized material (Sereno, 1993;Senter & Robins, 2005;Bonnan & Senter, 2007;Mallison, 2010b;Pierce, Clack & Hutchinson, 2012;Vargas-Peixoto, Da Rosa & Franca, 2015;White et al, 2015), elbow hyperextension close to 180° leads to a high risk of disarticulation. Similarly, maximal elbow flexion was 110-130° in the two taxa (regardless of resting or reference pose), so the total ROM was less in the resting pose vs. the reference pose.…”

Section: Discussionsupporting

confidence: 71%

Peer Review #2 of "Forelimb muscle and joint actions in Archosauria: insights from Crocodylus johnstoni (Pseudosuchia) and Mussaurus patagonicus (Sauropodomorpha) (v0.2)"

Hutson¹

2017

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Functional and biomechanic aspects of the scapular girdle and forelimbs of Unaysaurus tolentinoi Leal et al., 2004 (Saurischia: Sauropodomorpha)

Cited by 5 publications

References 37 publications

Forelimb muscle and joint actions in Archosauria: insights fromCrocodylus johnstoni(Pseudosuchia) andMussaurus patagonicus(Sauropodomorpha)

Forelimb muscle and joint actions in Archosauria: insights fromCrocodylus johnstoni(Pseudosuchia) andMussaurus patagonicus(Sauropodomorpha)

Resting Orientations of Dinosaur Scapulae and Forelimbs: A Numerical Analysis, with Implications for Reconstructions and Museum Mounts

Peer Review #2 of "Forelimb muscle and joint actions in Archosauria: insights from Crocodylus johnstoni (Pseudosuchia) and Mussaurus patagonicus (Sauropodomorpha) (v0.2)"

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