The subclass Corallinophycidae is the only group of red algae characterized by the presence of calcite crystals in their cell walls. Except for the Rhodogorgonales, the remaining orders - collectively called corallines - are diverse and widely distributed, having calcified cell walls and highly variable morphology. Corallines constitute the group with the richest fossil record among marine algae. In the present study, we investigate the evolutionary history of the subclass Corallinophycidae and provide a time-calibrated phylogeny to date the radiation of the crown group and its main lineages. We use a multi-locus dataset with an extensive taxon sampling and comprehensive collection of fossil records, carefully assigned to corallines, to reconstruct a time-calibrated phylogeny of this subclass. Our molecular clock analyses suggest that the onset of crown group diversification of Corallinophycidae started in the Lower Jurassic and sped up in the Lower Cretaceous. The divergence time of the oldest order Sporolithales is estimated in the Lower Cretaceous followed by the remaining orders. We discuss the long period of more than 300 million years between the early Paleozoic records attributed to the stem group of Corallinophycidae and the radiation of the crown group. Our inferred phylogeny yields three highly-supported suprageneric lineages for the order Corallinales; we confirm the family Mastophoraceae and amend circumscription of the families Corallinaceae and Lithophyllaceae. These three families are distinguished by a combination of vegetative and reproductive features. In light of the phylogeny, we discuss the evolutionary trends of eleven morphological characters. In addition, we also highlight homoplasious characters and selected autapomorphies emerging in particular taxa.

中文翻译：

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从多位点时间校准的系统发育学推断，珊瑚红藻（Corallinophycidae，Rhodophyta）冠群的辐射。

Corallinophycidae亚类是唯一一组以在其细胞壁中存在方解石晶体为特征的红藻。除Rhodogorgonales外，其余各科（统称为珊瑚线）种类繁多且分布广泛，具有钙化的细胞壁和高度可变的形态。珊瑚礁是海藻中化石记录最丰富的群体。在当前的研究中，我们调查了亚甲藻科的进化历史，并提供了一个经过时间校准的系统发育史，以测算冠群及其主要谱系的辐射史。我们使用具有广泛分类单元采样和化石记录的全面收集的多位置数据集，将其仔细分配给珊瑚线，以重建该子类的经过时间校准的系统发育史。我们的分子钟分析表明，Corallinophycidae科的冠群多样化开始于下侏罗纪开始，并在下白垩纪加速发展。估计下白垩统中最古老的孢子虫的发散时间，其次是其余的。我们讨论了古生代早期的记录（归因于Corallinophycidae的茎群）和冠群的辐射之间的超过3亿年的漫长时期。我们推断的系统发育产生了Corallinales阶的三个高度支持的suprageneric谱系。我们确认了鞭毛科，并修改了科科和石藻科的界限。这三个家族的特征是具有营养和生殖功能。鉴于系统发育，我们讨论了11种形态特征的演变趋势。此外，我们还将突出显示同质性状和特定类群中出现的部分自构型。