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To prior outcomes for Tyrannosaurus rex (Hutchinson et al., 2005). Ostriches, nevertheless, don’t stand or commonly move with such extended hip joints (Rubenson et al., 2007). We suspect this difference is since of their two orders of magnitude smaller physique size (65+ kg vs. 6,000+ kg) and therefore the lack of necessity for extreme postural modifications to retain reduce muscle stresses in order to maintain locomotor efficiency (Biewener, 1989; Biewener, 1990). Nonetheless, ostriches might also have a higher significance for non-isometric muscle force ength properties in figuring out the limb orientation employed (Figs. six and 7), as per the section above. Such speculations is usually tested improved once such physiological data exist for ostrich muscles. Our information also usually do not strongly support Smith et al.’s (2007) suggestion that hip extensor (or other muscle) moment arms are at peak values toward the end of stance phase (Figs. 6). All round, unfortunately the aspects that ascertain limb orientation in locomoting ostriches, as the largest extant striding biped (and theropod dinosaur) readily available for study,Hutchinson et al. (2015), PeerJ, DOI 10.7717/peerj.31/remain inconclusive, leaving the application of such buy alpha-Asarone principles to reconstructing limb orientations and locomotion in extinct theropods (e.g., Hutchinson et al., 2005; Gatesy, Bker Hutchinson, 2009) on shakier empirical and theoretical ground. Even so, this a uncertainty is just not result in for cynicism. It can be an opportunity for future improvement, particularly offered the dearth of comparative research that focus on how musculoskeletal mechanics relate to limb orientation, and also the technical issues inherent to measuring or modelling muscle moment arms along with other properties. In addition, quantitative biomechanical studies of extant or fossil organisms should really still be considered a significant step forward from past qualitative, intuitive or subjective functional research.How precise and repeatable are estimates of ostrich limb muscle moment armsOur study’s Question three dealt using a methodological comparison among the three key studies of ostrich pelvic limb muscle moment arms. Agreement seems fair all round, especially for flexion/extension actions. However, many primary messages emerge from our comparisons, a few of which had been also voiced by the other two studies of ostrich pelvic limb moment arms (Smith et al., 2007; Bates Schachner, 2012; right here “S.E.A”. and “B.A.S”.). Circumstantial assistance for all 3 methods’ accuracy moreover comes from tendon travel measurements of cranial and caudal components with the IL muscle in guineafowl by Carr et al. (2011). General patterns (their Fig. 7) for the IL moment arms regarding the knee (concave arc, peaking 100 knee angle in flexion) plus the hip (rising with extension) agree reasonably well with these three ostrich research (Figs. 12 and 16). Nevertheless, all moment arms for the ostrich IL muscle infer a switch to hip flexor action in strongly flexed poses, and tiny or no levelling off of the moment arm curve at robust hip flexion angles. Important areas of disagreement between our final results and those of B.A.S. and/or S.E.A. consist of occasionally major variations in if, or how, muscle tissues switch involving flexion and extension (e.g., the AMB1 and AMB2, IC, ILFB in regards to the hip; Fig. 91), PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19996636 whether particular muscle tissues are flexors or extensors (e.g., the OM; see “Implications for ostrich limb muscle function” under), or the absolute magnitudes or relative trends in the information (e.g., our near-constant moment arms abou.