The First Record of Eotrigonobalanus Furcinervis (Fagaceae) from the Oligocene of the Thrace Basin, Western Turkey

Eotrigonobalanus furcinervis was recorded for the first time from the Oligocene sediments of the Thrace Basin. The species was discovered in the upper part of the Danişmen Formation from the Marmaraereglisi Area, southeastern the Basin. Eotrigonobalanus furcinervis appeared in large numbers early during the early Paleocene–late Oligocene localities in Europe; especially in Thrace of Greece, Bulgaria, Germany, Czech Republic, Hungary and Romania. Therefore, this data is valuable as the first recording for Thrace Basin.


Introduction
The study area is around Marmaraereğlisi, located in the southeastern Thrace Tertiary Basin ( Figure  1). This study, it is aimed to contribute to the previous paleontological studies in the region.
This finding is the first evidence of Eotrigonobalanus furcinervis from the Oligocene of the Thrace Basin (Turkey) and is wellcome added to the European and Turkish records of that time.

Material and Method
This study was conducted to the paleontological evaluation of the core samples taken from the drillings opened around Marmaraereğlisi.
Fossil material consists of leaf, and although only one leaf was found, this data is precious. This new material, which will enrich the paleobotanical collection, is kept in Bilal Gülen's office.  Figure 1. Geology map of Thrace Basin [5], [24], [25].

Geological Settlement
The Istranca metagranites form the basis of the region. Paleogene and Neogene sediments unconformably overlie it [26].
The study was carried out within the Danişmen Formation belonging to the Yenimuhacir Group outcropping southeast part of Thrace Basin (Figures1,2).

Danişmen Formation
Danişmen Formation overlies in a large area extending from S of Uzunköprü to Keşan, Malkara, Tekirdağ, Marmaraereğlisi and Büyükçekmece in the Thrace region [27] [4] ( Figure 1). This formation has been described by [26], [6] regressive delta system and represents delta flat facies. The unit is composed of lacustrine, swamp, flood plain, and fluvial deposits. The thickness of the Danişmen Formation, which has shale, claystone, sandstone, conglomerate and lignite lithology, reaches 1000 meters. It is transitional with the Osmancık Formation at its lower boundary and inconsistent with the lacustrine and light-coloured limestones of the Neogene at its upper boundary [5], [25] (Figure 2).

Morphology:
The leaf is superficial, long, 15 mm wide, and maybe around 8 cm long as incomplete.  Eotrigonobalanus is a well-known extinct genus of highly heterogeneous leaf forms occurring mainly in the middle Eocene to the early Oligocene deposits of Europe and extending into the Miocene [30], [31], [32]. At the same time, it has been one of the essential elements in forming Paleogene forests in Europe [21], [33]. All records reported so far indicate that this taxon occurred in the Lower Rhine Embankment only in the pre-volcanic late Oligocene siliciclastic facies of the Siebengebirge and as a common element of the riparian forests there [34].
This new leaf material obtained in this study will contribute to the discovery of newer taxa and specimens. The new findings will increase our knowledge of the Thrace Basin Oligocene flora and vegetation from different geological eras. Kvaček (x2)