华北辽东本溪寒武纪三叶虫Redlichia(Pteroredlichia)murakamii蜕壳标本完好地保存了头盖向下翻转的蜕壳状态,为寒武纪Redlichia的蜕壳模式提供了新的视角。此标本自由颊未保留,胸尾相连,头盖与胸部分离,头盖向下翻转,基本保持原位,为原地埋藏的蜕壳标本。蜕壳过程如下:面线裂开,头盖耸起卷曲并翻转,与胸部分离,胸部扭动,虫体摆脱老壳向前爬出。此蜕壳方式在McNamara(1986)报道的澳大利亚寒武纪Redlichia的蜕壳类型中并未出现。
An uncommon form of exuviation, involving inversion of cranidium, is well preserved in a trilobite specimen of early Cambrian Redlichia ( Pteroredlichia ) murahamii Resser et Endo collected from the Benxi region in eastern Liaoning Province, North China. This specimen provides an important insight into the techniques of the exuviation of the Cambrian Redlichia. In this moulting specimen, free cheeks are not preserved, whereas thoracic segments are associated with pygidium, but displaced from the cranidium,which was inverted beneath thoracic segments without significant lateral displacement, indicating an autochthonous origin. The mechanism of the exuviation is interpreted as follows: the facial suture functioned efficiently and thus split first, followed by an upward thrust and the enrolment of the cephalon, which resulted in the inversion of the cranidium as well as the separation between thoracic segments, free cheeks and cranidium, and finally the postecdysial trilobite struggled to get rid of proecdysial exuvia. Such a form of exuviation for early Cambrian Redlichia in North China is different from those of the Cambrian Redlichia in Australia reported by McNamara (1986).