Katie M. Maloney, Dakota P. Maverick, J. Schiffbauer, G. Halverson, S. Xiao, M. Laflamme
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引用次数: 1
Abstract
Abstract. Proterozoic eukaryotic macroalgae are difficult to interpret because morphological details required for proper phylogenetic studies are rarely preserved. This is especially true of morphologically simple organisms consisting of tubes, ribbons, or spheres that are commonly found in a wide array of bacteria, plants, and even animals. Previous reports of exceptionally preserved Tonian (ca. 950–900 Ma) fossils from the Dolores Creek Formation of Northwestern Canada feature enough morphological evidence to support a green macroalgal affinity. However, the affinities of two additional forms identified on the basis of the size distribution of available specimens remain undetermined, while the presence of three unique algal forms supports other reports of increasing algal diversity in the early Neoproterozoic. Archaeochaeta guncho new genus new species is described as a green macroalga on the basis of its well-preserved morphology consisting of an unbranching, uniseriate thallus with uniform width throughout and possessing an elliptical to globose anchoring holdfast. A larger size class of ribbon-like forms is interpreted as Vendotaenia sp. A third size class is significantly smaller than Archaeochaeta n. gen. and Vendotaenia, but in the absence of clear morphological characters, it remains difficult to assign. As Archaeochaeta n. gen. and Vendotaenia represent photoautotrophic taxa, these findings support the hypothesis of increasing morphological complexity and phyletic diversification of macroalgae during the Tonian, leading to dramatic changes within benthic marine ecosystems before the evolution of animals.
摘要元古代真核巨藻很难解释,因为系统发育研究所需的形态学细节很少被保存下来。对于由管状、带状或球形组成的形态简单的生物体来说尤其如此,这些生物体通常存在于各种各样的细菌、植物甚至动物中。先前关于加拿大西北部Dolores Creek组保存完好的Tonian(约950-900 Ma)化石的报道,有足够的形态学证据支持绿色大藻的亲缘关系。然而,根据现有标本的大小分布确定的另外两种形式的亲和力仍未确定,而三种独特的藻类形式的存在支持了新元古代早期藻类多样性增加的其他报告。古毛藻(Archaeochaeta guncho)新属新种被描述为一种保存完好的绿色大藻,其形态由无分支、单列的菌体组成,整个菌体具有均匀的宽度,并具有椭圆形到球形的锚定支架。带状形态的一个较大的尺寸类被解释为Vendotaenia sp.。第三个尺寸类明显小于Archaeochaeta n. gen.和Vendotaenia,但由于缺乏明确的形态特征,仍然难以确定。由于Archaeochaeta n. gen和Vendotaenia是光自养分类群,这些发现支持了大型藻类在Tonian时期形态复杂性和种类多样化的增加,导致底栖海洋生态系统在动物进化之前发生了巨大变化的假设。
期刊介绍:
The Journal of Paleontology publishes original articles and notes on the systematics, phylogeny, paleoecology, paleogeography, and evolution of fossil organisms. It emphasizes specimen-based research and features high quality illustrations. All taxonomic groups are treated, including invertebrates, microfossils, plants, vertebrates, and ichnofossils.