Lauraceae is a large family of 58 genera with 2,500-3,500 species distributed in tropical and subtropical regions worldwide. Cryptocarya is one of the largest and most widespread genera in Lauraceae. Many fossil records of Cryptocarya have been previously reported, but their affinity to extant genera of Lauraceae needs more research to clarify. 

During a field study, researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences collected some lauraceous fossil woods from the Shengli Coal Mine, located near Meizi town in Ninger County, Yunnan Province, Southwest China. After careful anatomical and morphological studies, the researchers confirmed the fossil wood as a new species in the genus Cryptocarya. They named it Cryptocarya latiradiata to refer to the wide rays in the wood. 

The fossils of Cryptocarya latiradiata show a close affinity to Cryptocarya (Lauraceae) and are most similar to C. hainanensis from South China, northern Vietnam and Laos. They show similar anatomical features to the large genus Laurinoxylon, but have much broader (up to 12-seriate) rays. They also have scalariform perforation plates, the oil/mucilage cells in rays, axial parenchyma and among fibers. 

According to the researchers, the nearly coeval fossil woods of Cryptocarya latiradiata from the southern Yunnan are the second reliable pre-Quaternary macrofossil record of this genus known to date. The presence of this genus both in Yunnan and Fujian strongly suggests that the Cryptocarya was widespread in southern China during the middle Miocene. 

"Cryptocarya latiradiata is the first record of Lauraceae from the Dajie Formation," said SU Tao of XTBG. 

The researchers also performed paleoclimatic reconstructions. The data suggest that at least some extant species of Cryptocarya could survive in the middle Miocene of southern Yunnan, but the climate was too cool and dry for most species of the genus. Winter temperature was probably a limiting factor for them. 

"Our data provide new evidence for the occurrence of the termophyllous genus Cryptocarya in the middle Miocene vegetation of the southern Yunnan region," said SU. 

The study entitled "Fossil woods of Cryptocarya (Lauraceae) from the middle Miocene of Southwest China" was published in Review of Palaeobotany and Palynology.