See text Agathoxylon (also known by the synonyms Dadoxylon and Araucarioxylon[3]) is a form genus of fossil wood, including massive tree trunks.

[8] Agathoxylon were large trees that bore long strap-like leaves and trunks with small, narrow rays.

[5] Often the original cellular structure is preserved as a result of silica in solution in the ground water becoming deposited within the wood cells.

As a genus, Dadoxylon was poorly defined, and apart from Araucariaceae, has been associated with fossil wood as diverse as Cordaitales,[9] Glossopteridales and Podocarpaceae.

[10] The genus Agathoxylon, classified under the family Araucariaceae,[11] has nomenclatural priority over the genera Araucarioxylon and Dadoxylon.