High-resolution anatomical and isotopic analyses of extant tropical trees that lack distinct growth-rings have demonstrated the existence of "hidden" rhythmic patterns that reflect the seasonality of precipitations. Our hypothesis is that it might be possible to similarly extract significant paleoclimatic information from fossil trees that lack well-defined growth-rings. Our previous work has already demonstrated the feasibility of high-resolution isotopic (?18O and/or ?13C) analyses of fossil wood and their potential to significantly supplement classical anatomical observations, even in deep time (Paleozoic) specimens. We thus propose a pioneering interdisciplinary study in which our main objective will be to answer the following question: Can Paleozoic fossil trees lacking well-defined growth-rings provide environmental information beyond -or even different from the traditional interpretation of a "lack of seasonality"? We will use Early Carboniferous anatomically preserved trunks from Australia kept in the collections of Université Montpellier 2 to conduct in parallel (1) detail observations of the wood anatomy using thin-sections across the radius of selected trunks, and (2) high-resolution ?13C analyses of the same specimens. In addition we will conduct molecular analyses of organic matter in the fossil wood to evaluate the degradation state and diagenetic alteration of wood. Three different taxa of woody trees will be analyzed, including 2 from a same locality. Our results will be confronted with other types of environmental proxies for the Early Carboniferous of north-eastern Australia. This project will allow us to determine whether woods lacking well-defined growth-rings, which are relatively abundant in the fossil record, can provide more detailed environmental information than is usually thought. It will provide a methodological framework for further studies of fossil woods from the paleotropics.