Department of Ecology and Evolutionary Biology and Biodiversity Institute, University of Kansas, Lawrence, Kansas, 66045, USA.
Am J Bot. 2020 Jan;107(1):139-147. doi: 10.1002/ajb2.1416. Epub 2020 Jan 5.
The mahogany family (Meliaceae) is an angiosperm lineage comprising many species that are important elements in tropical ecosystems, and is often used as a study system to understand the evolution of tropical rainforests. While divergence time studies have estimated a Cretaceous origin for the family, no unequivocal fossils of that age have been described. Here, the first Cretaceous evidence for Meliaceae is reported, based on an exceptionally well-preserved fruit from the Upper Cretaceous (79-72 Ma, Campanian) of North America.
The fossil fruit was prepared using traditional paleobotanical techniques. Bayesian phylogenetic analyses using morphological and molecular data were conducted to assess the phylogenetic position of the Cretaceous fruit in Meliaceae and to assess the effect of morphology for inferring the overall pattern of phylogeny for the family.
The fruit consists of a fleshy mesocarp and a woody endocarp with a hollow center, nine locules, loculicidal sutures, and one subapically attached seed per locule that has an enlarged sarcotesta near the hilum. The combination of characters in this fruit is strikingly similar to the genus Melia L. Phylogenetic analyses recover the Cretaceous fruit as being closely related to Melia and highlights the effect of fruit morphological data for inferring the overall pattern of phylogeny in Meliaceae. There are a few structural differences between the fossil fruit of this study and Melia; thus, the newly characterized Cretaceous taxon is named Manchestercarpa vancouverensis gen. et sp. nov.
These results clearly confirm a Cretaceous origin for Meliaceae and that important tropical families were present prior to the development of modern tropical ecosystems in the Cenozoic.
桃花心木科（Meliaceae）是被子植物谱系的一个分支，包含许多在热带生态系统中非常重要的物种，通常被用作研究系统，以了解热带雨林的进化。虽然分化时间研究估计该科起源于白垩纪，但尚未描述出明确的那个时代的化石。在这里，根据北美上白垩纪（79-72 Ma，坎潘阶）保存极好的果实，首次报道了桃花心木科的白垩纪证据。
使用传统的古植物学技术对化石果实进行了处理。利用形态学和分子数据进行贝叶斯系统发育分析，以评估白垩纪果实在桃花心木科中的系统发育位置，并评估形态学对于推断该科整体系统发育模式的影响。
该果实由肉质中果皮和木质内果皮组成，中心有空腔，九个室，室间开裂缝线，每个室中有一个靠近种脐的基部附着的种子，种子具有扩大的种皮。这个果实的特征组合与 Melia L. 属非常相似。系统发育分析结果表明，白垩纪果实与 Melia 密切相关，突出了果实形态学数据对于推断桃花心木科整体系统发育模式的影响。本研究的化石果实与 Melia 之间存在一些结构差异；因此，新描述的白垩纪分类群被命名为 Manchestercarpa vancouverensis gen. et sp. nov.
这些结果清楚地证实了桃花心木科起源于白垩纪，并且重要的热带科在新生代现代热带生态系统发展之前就已经存在。
