Comptonia naumannii (Myricaceae) from the early Miocene of Weichang, China, and the palaeobiogeographical implication of the genus

Newly collected material of Comptonia leaves and fruits (C. naumannii and C. tymensis, respectively) from the lower Miocene of Weichang, China, are studied in detail. The leaves show great similarities in morphology and cuticular structures to those of the single extant species C. peregrina. It suggests a close genetic relationship between C. numannii and C. peregrina. Comptonia was widespread over the Northern Hemisphere during most of the Cenozoic, and obviously migrated into Asia from North America via a continental connection in the Eocene. Due to the cooling of global climate, it may have later gradually evolved into two ecotypes (thermophilous and cold tolerant). In the early Miocene C. naumannii was recorded from Northeast Asia and Alaska, but it disappeared from Alaska in the latest Miocene. The records suggest that plant exchange between Northeast Asia and North America may have ceased after the early Miocene.