Yimaia Explained

Yimaia is an extinct genus of Ginkgoalean tree, and the only member of the family Yimaiaceae. In botanical form classification, its a form taxon for ginkgoalean ovulate organs. Yimaia species are distinguished from other Ginkgoales by the presence of "Ovulate organs consisting of a peduncle and up to eight or nine terminal, sessile, contiguous and orthotropous (straight, upright and with a micropyle at apex) ovules." The ovules are associated with leaves of either Baiera or Ginkgoites leaf morphospecies.^[1] Fossils have been found in Middle Jurassic deposits in China.

Species

• Yimaia capituliformis Zhou, Zheng and Zhang, 2006 Daohugou Bed, China, Callovian^[2] Associated with leaves of Ginkgoites type
• Yimaia qinghaiensis Wu, Yang and Zhou, 2006 Shimengou Formation, Qinghai, China, Middle Jurassic^[3] Associated with leaves of Baiera furcata type.
• Yimaia recurva (type) Zhou et Zhang, 1988 Yima Formation, Henan, China, Middle Jurassic

Notes and References

1. Zhou. Zhi-Yan. March 2009. An overview of fossil Ginkgoales. Palaeoworld. en. 18. 1. 1–22. 10.1016/j.palwor.2009.01.001.
2. Zhou. Zhiyan. Zheng. Shaolin. Zhang. Lijun. April 2007. Morphology and age of Yimaia (Ginkgoales) from Daohugou Village, Ningcheng, Inner Mongolia, China. Cretaceous Research. en. 28. 2. 348–362. 10.1016/j.cretres.2006.05.004.
3. Wu. Xiangwu. Yang. Xiaoju. Zhou. Zhiyan. April 2006. Ginkgoalean ovulate organs and seeds associated with Baiera furcata-type leaves from the Middle Jurassic of Qinghai Province, China. Review of Palaeobotany and Palynology. en. 138. 3–4. 209–225. 10.1016/j.revpalbo.2006.01.009.