广东东莞木化石的首次发现

On the Occurrence of Fossil Wood in Dongguan, Guangdong

在广东东莞晚白垩世地层中首次发现一种新型木化石，定名为东莞云杉型木（新种）Ｐｉｃｅｏｘｙｌｏｎｄｏｎｇｇｕａｎｅｎｓｉｓ（ｓｐ．ｎｏｖ）．

The fossil wood-Piceoxylon dongguanensis sp. nov. was collected from the Late Cretaceous strata of Dongguan City, Central Guangdong. The strata also yield some macrofossil plants and abundant sporopollens of Late Cretaceous (Turonian) in age. The fossil wood represents a trunk base, about 4 m in length and ranging from 70 cm × 30 cm to 90 cm × 40 cm in size. Its periphery, about 2￣ 3 cm in thickness, being charcoalified, shows the internal structure of the secondary xylem, which is studied by scanning electron micrograph (SEM). In transverse sections, growth rings are somewhat distinct and the tracheids are square or polygonal in outline.The resin canals are small and separated from one to another. The bordered pits in the radial walls are seen to be in one row. The pits are small, elliptical, separated from each other. The pitwapertures are fusiform. some with pit membrane. Bars of Sanio absent. Medullary rays parenchymatous, some horizontal walls with spiral thickenings, abietinean pittings 1 ￣ 3 per field, oval or fusiform. In tangential sections only one uniseriate ray (3 cells in height) can be seen, no horizontal resin canals are preserved. There are some tracheids with spiral thickenings but without bordered pits.