Wairarapaia mildenhallii gen. et sp nov., a new Araucarian cone related to Wollemia from the cretaceous (Alrian-Cenomanian) of New zealand
Wairarapaia mildenhallii gen. et sp nov., a new Araucarian cone related to Wollemia from the cretaceous (Alrian-Cenomanian) of New zealand
复制标题
DOI：
10.1086/507608
复制
发表时间：
2006-11-01
影响因子：
2.3
通讯作者：
Raine, J. Ian
中科院分区：
文献类型：
--
作者：
Cantrill, David J.;Raine, J. Ian
摘要新西兰白垩纪（晚Albian至Cenomanian）发现了一种新的属和种Wairarapaia mildenhallii Cantrill et Raine，该属和种具有两个螺旋插入的圆锥体和一个中心位置的倒胚珠的卵生球果。球果直径可达60毫米，呈楔形圆锥状复合体，至少长18毫米，宽8毫米，翅窄，顶脊短。胚珠位于圆锥体复杂表面的一个明显的中空中心，但仅由基部的组织垫附着。胚珠取向，珠孔面向圆锥轴。它们有短的侧翼，被解释为从锥形复合体中开裂。其球果组织表明其与龙葵科有亲缘关系。种子有一个狭窄的附着点，类似于在Agathis和Wollemia中看到的，而与Araucaria非常不同，后者的胚珠嵌入在锥状复合体中。最近的系统发育分析表明，需要重新评估用于将化石分类群分配给阿劳亚的特征。这个圆锥体支持了这样一种观点，即许多记录的龙葵类化石代表了龙葵科的基础谱系，而不是龙葵属的灭绝成员。
A new genus and species, Wairarapaia mildenhallii Cantrill et Raine, is established for two ovulate cones with helically inserted cone-scale complexes and a centrally positioned inverted ovule from the Cretaceous (late Albian to Cenomanian) of New Zealand. The cones are up to 60 mm in diameter with wedge-shaped conescale complexes, at least 18 mm long by 8 mm wide and with narrow wings and a short apical spine. The ovules sit centrally in a distinct hollow on the cone-scale complex surface but are attached only by a basal pad of tissue. Ovules are oriented with the micropyle facing the cone axis. They have short lateral wings and are interpreted to be dehiscent from the cone-scale complex. The cone organization suggests affinities with the Araucariaceae. The seed has a narrow attachment point similar to that seen in Agathis and Wollemia and quite unlike that of Araucaria, where the ovule is embedded in the cone-scale complex. Recent phylogenetic analyses suggest that features used to assign fossil taxa to Araucaria need to be reevaluated. This cone supports the notion that many records of Araucaria-like fossils represent basal lineages within the Araucariaceae rather than extinct members of the genus Araucaria.