FOSSIL WOODS OF LEGUMINOSAE FROM THE ITUZAINGÓ FORMATION, ENTRE RÍOS, ARGENTINA: PALEOECOLOGICAL AND PALEOBIOGEOGRAPHIC IMPLICATIONS. The family Fabaceae is among the best represented in the fossil record of the Cenozoic of Argentina and in particular of the Ituzaingó Formation. This paper describes four types of permineralized by silicification woods related to this family, Menendoxylon vasallensis Lutz, Anadenantheroxylon villaurquicense Brea, Aceñolaza y Zucol emend., Prosopisinoxylon americanum sp. nov. and Gleditsioxylon paramorphoides sp. nov. Two new fossil species were recognized and the diagnosis of Anadenantheroxylon villaurquicense was amended. The specimens were found in the Ituzaingó Formation (Pliocene—Pleistocene), Entre Rios, Argentina, and have only preserved the anatomy of secondary xylem. Some anatomical features were related with the presence of a seasonal and dry climate. From paleogeographic and paleoecological features of distribution of most related extant genera, it is proposed that during the Pliocene—Pleistocene developed a heterogeneous environment characterized by having arboreal elements linked to Chaco, riparian and component of Seasonally Dry Tropical Forests (SDTF). The presence of the studied fossil wood in the Ituzaingó Formation (Pliocene—Pleistocene) in the Paraná Basin shows a rich flora linked to SDTF southermost of its current distribution, supporting the hypothesis that had a greater extent in South American continent during the late Cenozoic.