Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur 721 302, India.
J Biosci. 2009 Nov;34(5):661-72. doi: 10.1007/s12038-009-0055-x.
Bone microstructure is affected by ontogeny, phylogeny, biomechanics and environments. These aspects of life history of an extinct animal, especially its growth patterns, may be assessed as fossil bone generally maintains its histological integrity. Recent studies on the bone histology of fossil vertebrates from India encompass different types of temnospondyls and dicynodonts from different Permian and Triassic horizons. The examined taxa show that they had distinct bone histology and varied growth patterns. The Early Triassic trematosaurids had an overall fast growth, which contrasts with that of the Middle and Late Triassic temnospondyl taxa examined. The dicynodonts on the other hand, were characterized by an overall fast growth with periodic interruptions, variable growth rates dependent on ontogeny and indeterminate growth strategy. A comparative study encompassing several neotherapsid genera including the dicynodonts shows signifi cant evolutionary trends towards determinate growth strategy and reduced developmental plasticity.
骨骼微观结构受个体发生、系统发生、生物力学和环境的影响。作为一种已灭绝动物的生活史的这些方面，尤其是其生长模式，可能可以通过化石骨骼通常保持其组织学完整性来评估。最近对印度化石脊椎动物骨骼组织学的研究涵盖了来自不同二叠纪和三叠纪地层的不同类型的合弓类和兽孔目动物。所研究的分类群表明，它们具有不同的骨骼组织学和不同的生长模式。早三叠世的混鱼龙类具有整体快速生长的特点，这与中晚三叠世所研究的合弓类动物的生长模式形成对比。另一方面，兽孔目动物的特点是整体快速生长，但有周期性中断，生长速率因个体发生而异，具有不定型生长策略。一项包括几个新兽脚亚目属的比较研究表明，这些属朝着定型生长策略和降低发育可塑性的方向有显著的进化趋势。
