基于对采自西藏札达姜叶玛剖面上二叠统姜叶玛组的块状四射珊瑚Ipciphyllum naoticum (喷口伊泼雪珊瑚)的连续切片, 详细描述其中返青个体重新生长的过程, 包括轴部返青和边部返青两种类型。两类返青现象因为返青程度不同, 重新生长的过程不尽相同, 指示的生态环境也不同: 轴部返青的个体回到了更早的青年期, 可能与种内竞争导致的食物不足有关; 边部返青的个体回到胚胎期重新生长, 可能是由于虫体受到较大的伤害, 仅有碎片存活。在块状珊瑚中, 这种个别珊瑚体返青的现象与虫体的个体状况有关, 与大的生存环境的变化无关。

This study focuses on the rejuvenescences in massive rugose coral Ipciphyllum naoticum from the Late Permian Gyanyima section in Xizang, southwest China. Two types of rejuvenescences, axial and lateral, are observed. Based on serial thin sections, the process of rejuvenescence is described. The skeletal characteristics of axial and lateral rejuvenescences in I. naoticum are significantly different, due to the regrowth of related corallite from different stages of ontogeny. The axial rejuvenated corallite regrow from an earlier juvenile stage. The diameter of the rejuvenated individuals significantly decreases, however, the axial columns of the original and rejuvenated corallites are not only continuous, but also have little change in size. This phenomenon may be due to the polyp being squeezed by adjacent polyps, reducing its space and making it more difficult to get sufficient food. Nutrient deficiency leads to a decrease in corallite diameter. The lateral rejuvenated corallite regrow from the brephic stage, and subsequently build new axial column, independent of the axial column of the original corallite. This phenomenon may be related to polyp health or injury. The regrowth of rejuvenated corals from the brephic stage or a younger stage depends on the overall condition of the polyp. If the polyp is relatively healthy, it may regrow from a younger stage. If only remnant tissue fragments survive, the rejuvenated coral may secrete skeleton from the brephic stage. In this study, the size of remnant tissue fragments of the lateral rejuvenated corallite that regrow from the brephic stage is limited. It can be inferred that the polyp fragments of some rugose corals, including I. naoticum, can also regrow like extant corals. In massive corals, individual rejuvenation may be related to the overall condition of the polyps, including injury and intraspecific competition, rather than the surrounding environment.

国家自然科学基金项目(40792010)资助