Ten new petrified forest sites have been discovered on the Galatian Volcanic Province (GVP). The silicified woods, preserved in the lower Miocene Hançili and Pazar formations, represent a diverse plant assemblage that grew across western and central GVP during the Burdigalian, ca. 20-17 Ma. The assemblage comprises a total of 233 petrified woods collected from the 10 sites in and around Ankara (Beypazarı, Çamlıdere, Kızılcahamam) and Bolu (Kıbrısçık). Taxonomic identifications of the fossil wood floras suggest four distinct vegetational associations can be recognized on the GVP: (1) swamp associations of Glyptostrobus Endlicher, Sequoia Endlicher and Taxodium Richard; (2) riparian forest comprising palms, Salix L., Liquidambar L. and Quercus L. section Ilex; (3) mesic-xeric woodland comprising Acer L., Quercus L., Pinus L. and Juniperus L.; and (4) mixed coniferous-angiosperm forest comprising Picea A. Dietrich, Cedrus Trew., Pinus, Juniperus L. and Podocarpus L'Herit (ex Pers.) alongside. These associations support the idea that the landscape was varied and the climate warm and frost free.

Abstract Taxodioxylon Hartig (emended by Gothan 1905) was widely described from the late Oligocene of the European part of Turkey (Thrace) and the early Miocene of greater Turkey, Anatolia. Glyptostroboxylon Conw. was also described from the early Miocene of central Anatolia. The purpose of this paper is to present a more detailed extended history of these two genera up to the late Miocene (Tortonian) with new descriptions from the Galatean Volcanic Province in central Turkey. The wood identification showed the presence of two fossil species; Glyptostroboxylon rudolphii Dolezych et Burgh and Taxodioxylon gypsaceum (Göpp.) Greguss. In conclusion, the swamp and lowland warm-temperate forest composition including Glyptostroboxylon and Taxodioxylon in the Galatean Volcanic Province, continued from the early Miocene (Burdigalian) to the late Miocene (Tortonian).

In this study, xeromorphy ratios were calculated for Acer L. (maple) fossil woods in order to infer the precipitation conditions in the Miocene at the sites of the fossils, based on a comparison with the xeromorphy ratios of selected extant Acer species. The four studied petrified wood samples came from three localities of the Galatean Volcanic Province in Turkey: Kozyaka village (Bolu Province, Seben District), İnözü Valley (Ankara Province, Beypazarı District), and Kıraluç precinct between Nuhhoca and Dağşeyhler villages (Ankara Province, Beypazarı District). The calculated xeromorphy ratios ranged from 3 to 18 for the present-day wood and from 13 to 19 for the early Miocene wood. Values over 10 (11–18) represent xeric conditions; the lower values (3–7) indicate mesic conditions in modern Acer woods. The xeromorphy ratios of the Miocene wood indicate xeric conditions; we conclude that the sites of the fossil Acer woods were xeric, very similar to the modern Acer woodlands of central and southern Anatolia.