56-7 Multivariate Analysis of Cordaitales Xylem Anatomy Reveals Challenges in Distinguishing Extinct Taxa from Modern Conifers

Session: Phylogenetic and Computational Approaches in Paleobiology and Paleoecology, Part II

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The relationship of Cordaitales to extant conifers is a topic of debate amongst researchers: additionally, the water transport of Cordaitales through the xylem is still obscure. Based on the xylotomy of modern conifer species and the ability to separate conifer species by certain xylem measurements, it may be possible to both understand how Cordaitales transported water and how they are related to conifers using existing literature. To better visualize variance and separation between groups, PCA and LDA were used on continuous variables such as tracheid width, pit size, and ray height. Based on the results of the PCA and LDA, there is some evidence to support that Cordaitales could be different from Cupressaceae and perhaps other conifers in terms of xylem traits such as tracheid width and pit sizes, but given the current variables and samples, Araucariaceae is too similar to samples of Cordaitales. This similarity between Araucariaceae and Cordaitales may be due to taxonomic affinity as Araucarioid pitting is used to describe many Cordaitales plants or the similarity could be due to similar environmental conditions for the two plant groups.  This study may expand our understanding of how Cordaitales transported water compared to modern conifers and may explain the taxonomic relationship Cordaitales share with modern conifers.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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