MINIATURIZATION AND ITS EFFECTS ON CRANIAL MORPHOLOGY IN PLETHODONTID SALAMANDERS, GENUS THORIUS (AMPHIBIA, PLETHODONTIDAE) .1. OSTEOLOGICAL VARIATION
MINIATURIZATION AND ITS EFFECTS ON CRANIAL MORPHOLOGY IN PLETHODONTID SALAMANDERS, GENUS THORIUS (AMPHIBIA, PLETHODONTIDAE) .1. OSTEOLOGICAL VARIATION
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DOI：
10.1111/j.1095-8312.1984.tb00806.x
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发表时间：
1984-01-01
影响因子：
1.9
通讯作者：
HANKEN, J
中科院分区：
文献类型：
--
作者：
HANKEN, J
研究了5种鱼类的头骨形态、个体发育和变异。属于Thorius，一个小型的plethodontid蝾螈属，是现存最小的有尾四足动物之一。成年Thorius的头骨的特点是：有限的发展或缺乏几个骨化的元素和齿系;增加种间和种内的变化和新的形态配置的braincase和颌骨suspensorium。在所有种类的Thorius的后帽颅矿化是截断早熟的典型的较大和更普遍的plethodontid属，如Pseudoeurycea。这些功能牵连pedomorphosis作为一个主要的机制，负责在Thorius从更大的plethodontid祖先的大小减少的演变。颅形态的种间差异是明显的;物种的特点可能是或多或少程度的截断发展。在种间比较中，幼态化程度与成虫平均体长之间没有一致的关系。成虫形态的几个单独的元素代表了潜在的有用的分类特征，用于区分物种。减少，增加的变异性，和形态的新奇是共同的许多谱系矮化类群。他们代表了一个零假设的发展机制和其他群体的小型化形态后果的检查。
Cranial skeletal morphology, ontogeny and variation are examined in 5 spp. of Thorius, a genus of diminutive plethodontid salamanders that are among the smallest, extant, tailed tetrapods. The skull of adult Thorius is characterized by: limited development or absence of several ossified elements and dentition; increase inter- and intraspecific variability and novel morphological configurations of the braincase and jaw suspensorium. Posthatching cranial mineralization in all species of Thorius is truncated precociously with respect to that typical of larger and more generalized plethodontid genera, such as Pseudoeurycea. These features implicate pedomorphosis as a predominant mechanism responsible for the evolution of decreased size in Thorius from larger plethodontid ancestors. Interspecfic differences in cranial morphology are evident; species may be characterized by greater or lesser degrees of truncated development. There is no consistent relationship between degree of pedomorphosis and mean adult body size in interspecific comparisons. Adult morphology of several individual elements represent potentially useful taxonomic characters for distinguishing species. Reduction, increased variability, and morphological novelty are common to many lineages of dwarfed taxa. They represent a null hypothesis for examination of the developmental mechanisms and morphological consequences of miniaturization in other groups.