Hickory: Difference between revisions

Fossil and molecular data suggest the genus ''Carya'' may have diversified during the [[Miocene]].<ref name="Zhang2013">{{cite journal |author1=Zhang, Jing-Bo |author2=Rui-Qi Li |author3=Xiao-Guo Xiang |author4=Steven R. Manchester |author5=Li Lin |author6=Wei Wang |author7=Jun Wen |author8=Zhi-Duan Chen |title=Integrated Fossil and Molecular Data Reveal the Biogeographic Diversification of the Eastern Asian-Eastern North American Disjunct Hickory Genus (Carya Nutt.) |journal=[[PLOS ONE]] |date=2013 |url=https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0070449}}</ref> Recent descriptionsdiscoveries of ''Carya'' fruit fossils further support the hypothesis that the genus has long been a member of Eastern North American landscapes, however its range has contracted and Carya is no longer extant west of the [[Rocky Mountains]].<ref name="Huang2014">{{cite journal |author1=Huang, Y.J. |author2=Yusheng Liu |author3=M.S. Zavada |title=New fossil fruits of Carya (Juglandaceae) from the latest Miocene to earliest Pliocene in Tennessee, eastern United States |journal=Journal of Systematics and Evolution |date=2014 |doi=10.1111/jse.12085}}</ref><ref name="MissisippiMiocene">{{cite journal |author1=McNair, D.M. |author2=D.Z. Stults |author3=B. Axsmith |author4=M.H. Alford |author5=J.E. Starnes |title=Preliminary investigation of a diverse megafossil floral assemblage from the middle Miocene of southern Mississippi, USA |journal=[[Palaeontologia Electronica]] |date=2019 |doi=10.26879/906 |url=https://palaeo-electronica.org/content/pdfs/906.pdf}}</ref>

The earliest ancestors of hickories are identified from [[Cretaceous]] pollen grains.{{Citation needed}} The ''Carya'' as we know it first appears in [[Oligocene]] strata 34 million years ago. Fossils of early hickory nuts show simpler, thinner shells than modern species with the exception of [[pecan]]s, suggesting that the trees gradually developed defenses to [[rodent]] seed predation.{{Citation needed}} During this time, the genus had a distribution across the Northern Hemisphere, but the [[Pleistocene Ice Age]] beginning 2 million years ago completely obliterated it from Europe.{{Citation needed}} The distribution of Carya in North America also contracted and it completely disappeared from the continent west of the [[Rocky Mountains]]. Since fossil records show North America as having the largest number of Juglandaceae species, it is likely that the genus originated there and later spread to Europe and Asia.{{Citation needed}}