Petrified Tree or Araucarioxylon arizonicum

"Araucarioxylon arizonicum" is an extinct species of conifer that is the state fossil of Arizona. The species is known from massive tree trunks that weather out of the Chinle Formation in desert badlands of northern Arizona and adjacent New Mexico, most notably in the 378.51 square kilometres Petrified Forest National Park. There, these trunks are locally so abundant that they have been used as building materials.