To prior benefits for Tyrannosaurus rex (Hutchinson et al., 2005). Ostriches, on the other hand, usually do not stand or usually move with such extended hip joints (Rubenson et al., 2007). We suspect this difference is for the reason that of their two orders of magnitude smaller sized body size (65+ kg vs. 6,000+ kg) and therefore the lack of necessity for extreme postural modifications to sustain reduced muscle stresses so as to retain locomotor performance (Biewener, 1989; Biewener, 1990). Even so, ostriches may possibly also possess a higher value for non-isometric muscle force ength properties in determining the limb orientation applied (Figs. 6 and 7), as per the section above. Such speculations could be tested superior when such physiological data exist for ostrich muscles. Our data also 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 variables that identify limb orientation in locomoting ostriches, because the largest extant striding biped (and theropod dinosaur) accessible for study,Hutchinson et al. (2015), PeerJ, DOI 10.7717/peerj.31/remain inconclusive, leaving the application of such 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. However, this a uncertainty is just not bring about for cynicism. It can be an opportunity for future improvement, especially given the dearth of comparative research that focus on how musculoskeletal mechanics relate to limb orientation, and the technical issues inherent to measuring or modelling muscle moment arms along with other properties. Furthermore, quantitative biomechanical studies of extant or fossil organisms should nevertheless be deemed a significant step forward from previous qualitative, intuitive or subjective functional studies.How precise and repeatable are estimates of ostrich limb muscle moment armsOur study’s Question three dealt with a methodological comparison amongst the three primary studies of ostrich pelvic limb muscle moment arms. Agreement appears fair general, in particular for flexion/WAY-200070 chemical information extension actions. Nevertheless, various major messages emerge from our comparisons, a few of which have been also voiced by the other two studies of ostrich pelvic limb moment arms (Smith et al., 2007; Bates Schachner, 2012; here “S.E.A”. and “B.A.S”.). Circumstantial help for all 3 methods’ accuracy also comes from tendon travel measurements of cranial and caudal parts of the IL muscle in guineafowl by Carr et al. (2011). Basic patterns (their Fig. 7) for the IL moment arms regarding the knee (concave arc, peaking 100 knee angle in flexion) along with the hip (rising with extension) agree reasonably properly with these 3 ostrich studies (Figs. 12 and 16). Even so, all moment arms for the ostrich IL muscle infer a switch to hip flexor action in strongly flexed poses, and small or no levelling off on the moment arm curve at robust hip flexion angles. Key areas of disagreement in between our benefits and those of B.A.S. and/or S.E.A. consist of occasionally key variations in if, or how, muscles switch involving flexion and extension (e.g., the AMB1 and AMB2, IC, ILFB about the hip; Fig. 91), PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19996636 whether specific muscles are flexors or extensors (e.g., the OM; see “Implications for ostrich limb muscle function” beneath), or the absolute magnitudes or relative trends inside the data (e.g., our near-constant moment arms abou.