Two new species of Ginkgoales from the Middle Jurassic of Mexico

This paper reports two new species of Ginkgoales collected from the Cañada Alejandro and Río Ñumi (Zorrillo and Zorrillo–Taberna Undifferentiated Formations, Middle Jurassic). Thirty-one fossils were selected and compared with 14 species from different localities. A numerical taxonomy analysis was performed through a data matrix formed by 15 characters. Results indicate an important speciation process of the Ginkgoales during the Jurassic in the southeast of Mexico. New evidence suggests the existence of eight species from the <i>Ginkgoidium</i> Yokoyama, 1889 and <i>Sphenobaiera</i> (Florin) Harris and Millington, 1974 genera and two new species <i>Ginkgoidium</i><i>nundichii</i> Velasco-de León, Lozano-Carmona, Flores, Martínez and Silva and <i>Sphenobaiera</i><i>mixteca</i> Velasco-de León, Lozano-Carmona, Flores, Martínez and Silva