Inferences about interactions between woods of gymnosperms and angiosperms

MARTINEZ, LEANDRO CARLOS ALCIDES; LEPPE, MARCELO; TREVISAN, C.; PINO, J.P.; MANSILLA, H.

Buenos Aires

Congreso; XII Congreso de la Asociación Paleontológica Argentina; 2021

Asociación Paleontológica Argentina

A diverse and distinct Late Cretaceous floral assemblage, in the southern of Chile (Dorotea Formation), composed by gymnosperms and angiosperms presents evidence of interactions between two seed plants. The fossils are housed in the paleontological collection of Instituto Antártico Chileno in Punta Arenas, Chile. The fossils here described are a gymnosperm and angiosperms. The gymnosperm has a system of rootles (root grafts?) in the stem of a tree. The host is a permineralized magnoliophyta fossil wood assigned to Paraphyllanthoxylon sp. with good tissue preservation. The gymnosperm possesses a system of roots, which penetrates into the xylem of Paraphyllanthoxylon in several directions. Theses roots possess primary and secondary xylem, pericycle, cortex, and epidermis. The secondary xylem has uniseriate bordered pits and uniseriate rays. The specimen of Paraphyllanthoxylon could be interpreted as a nurse wood similar to those seen in some living and fossil forests. However, in some sections the tissues of roots embedded into the xylem of the host are indistinguishable from each other. This is according to an early mode of parasitism and could be the starting point to explain the evolution of the more specialized modes. This record shows another way in which parasitism in some plants could have evolved.