A new cupressaceous wood from the Lower Cretaceous of central Patagonia reveals possible clonal growth habit

Abstract

A new genus and species, Austrocupressinoxylon barcinense, based on remains of cupressaceous wood is described for the Lower Cretaceous of central Patagonia, Argentina. The studied specimens are silicified fragments of picnoxylic and homoxylic wood that exhibit a combination of characters not previously reported, therefore a new genus is erected. The characters are: 1- growth ring boundaries distinct, 2- transition from earlywood to latewood gradual, 3- axial parenchyma diffuse,4- radial tracheid pitting predominantly abietinean,5- cross-field pitting cupressoid, arranged in both cupressoid and araucarioid patterns, 6- rays uniseriate heterocellular, 7- end and horizontal walls of ray parenchyma cells smooth or slightly nodular, and 8- ray tracheids with smooth walls. The cross-field pitting patterns and the presence of ray tracheids are two traits of particular interest in the context of systematic affinities. The fragments were collected from two stumps found in life position attached to each other by a main root, consequently, the disposition of the stumps suggests a case of clonal growth by root suckering. This is the second report of such mechanisms in the fossil records worldwide and the first one for South America.