The humerus ofOssinodus pueri, a stem tetrapod from the Carboniferous of Gondwana, and the early evolution of the tetrapod forelimb

AbstractBishop, P.J., 2014. The humerus of Ossinodus pueri, a stem tetrapod from the Carboniferous of Gondwana, and the early evolution of the tetrapod forelimb. Alcheringa 38. ISSN 0311–5518.The humerus of the Carboniferous stem tetrapod Ossinodus pueri is described on the basis of a recently discovered specimen. Its exceptional preservation records abundant, direct evidence of muscle attachment in remarkable detail. The surface of the bone is covered with hundreds of fine, elongate, asymmetrical pits, which are interpreted as the attachment scars of individual muscle fascicles. Re-examination and further preparation of other, previously described pectoral appendicular elements of Ossinodus reveals that they too record direct evidence of muscle attachment. The patterns of scarring and inferred muscle attachment on the humerus and other bones are described and discussed. In turn, the pectoral musculoskeletal system of this animal is able to be reconstructed in detail, based on comparison to extant primitive tetrapods. In addition to providing an anatomical basis for biomechanical analysis of the locomotor capabilities of early tetrapods, this sheds much new light on the early evolution of the tetrapod forelimb. Importantly, most of the pectoral musculature of extant tetrapods appeared prior to the origin of the crown group, and much of this was present in primitive stem tetrapods such as Ossinodus.Peter J. Bishop [peter.bishop@qm.qld.gov.au], Ancient Environments Program, Queensland Museum, 122 Gerler Road, Hendra, Queensland 4011, Australia. Received 4.6.2013; revised 14.8.2013; accepted 22.10.2013.根据新近发现的标本,本文描述了石炭纪主干四足动物Ossinodus pueri的肱骨。其特别的保存记录了丰富、直接、详细的肌肉附着证据。骨骼的表面覆盖有数百个细的、长的、不对称的凹坑,这些凹坑被解释为单个肌束附着痕。对以前描述的Ossinodus的肩胛部附加骨的重检测,表明它们也记录了肌肉附着的直接证据。本文对肱骨和其他骨骼上的疤痕形态和所推断的附肌痕进行了描述和讨论。反过来,这种动物的肩胛肌骨骼系统可以基于与现存原始四足动物的比较而重建。除了为早期四足动物运动能力的生物力学分析提供解剖学基础,这还对四足动物前肢的早期演化提供了新的了解。重要的是,大多数现存四足动物的肩胛肌出现在冠群起源之前,而很多存在于如Ossinodus的原始主干四足动物。Key words: Ossinodustetrapodmusculoskeletal anatomyforelimbevolutionCarboniferous. AcknowledgementsThe guidance and supervision by Dr M.J. Phillips during the undertaking of this research is gratefully acknowledged. For provision of high-quality photographs or casts of comparative material, or for discussion of the topics covered here, the following people are sincerely thanked: Drs A.A. Warren, C.A. Boisvert, K. Pawley, S.A. Hocknull, A.G. Cook, S. Turner, C.J. Burrow and S.A. Walsh, Profs J.A. Clack, P.E. Ahlberg and N.H. Shubin and Ms S.D. Chapman. Dr Burrow, Ms S.J. Thomsett, Ms K. Butler and Ms R.A. Lawrence provided valuable assistance in taking photographs. The final manuscript benefited substantially from the constructive comments of Dr Phillips and three anonymous reviewers, as well as those of the editors, Drs S. McLoughlin and B.P. Kear. This research was supported by a Summer Vacation Scholarship awarded by the Queensland University of Technology, Brisbane, as well as the Ancient Environments Program of the Queensland Museum.