| Ginkgo cranei | |
|---|---|
 | |
| Reconstruction ofGinkgo cranei by B.M. Begović Bego and Z. Zhou, 2012[1] | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Gymnospermae |
| Division: | Ginkgophyta |
| Class: | Ginkgoopsida |
| Order: | Ginkgoales |
| Family: | Ginkgoaceae |
| Genus: | Ginkgo |
| Species: | †G. cranei |
| Binomial name | |
| †Ginkgo cranei Zhou, Quan, & Liu, 2012 | |
Ginkgo cranei is an extinctGinkgo species in the familyGinkgoaceae described from a series of isolatedfossilovulate organs andleaves. The species is known fromupper Paleocene sediments exposed in the state ofNorth Dakota, US. It is the firstGinkgo species to be described fromPaleogene period with reproductive structures.[2]
Ginkgo cranei is represented by a group of fossil specimens from the Upper Paleocene agedSentinel Butte Formation exposed near the town ofAlmont, North Dakota. The specimens are preserved in a fine-grained yellow- to brown-coloredshale with a notably high iron content. Fossils found in the shales are often three-dimensionally preserved with stem and seed structure intact. The age of the formation is based on the recovery oflate Tiffanian mammals in the upper section of the formation along with the floral andpalynological assemblages of the formation. Many of theG. cranei seeds are preserved as casts with hollow crystalline interiors and exterior cuticle present. Associated with the ovulate organs are fossil leaves that were formerly assigned to the taxonGinkgo adiantoides.[2]
Thetype specimens forG. cranei include two ovulate organ fossils, aholotype and aparatype. The holotype is numbered number UWSP42706 which, along with four other specimens, is currently preserved in thepaleobotanical collections ofUniversity of Wisconsin–Stevens Point inStevens Point, Wisconsin.[2] The paratype, number PP34187, along with one additional specimen, are part of thegeology collections maintained at theField Museum of Natural History inChicago, Illinois. A total of only sevenG. cranei ovulate organ fossils were known at the time of the species description.[2] The specimens were studied by paleobotanist Zhiyan Zhou ofNanjing University, Cheng Quan ofJilin University and Yu-Sheng (Christopher) Liu ofEast Tennessee State University. Zhou and associates published their 2012type description forG. cranei in theInternational Journal of Plant Sciences. The chosenspecific namecranei was in honor ofSir Peter Crane who, with Steven Manchester and David Dilcher, first discovered the AlmontGinkgo fossils.[2]
G. cranei ovulate organs are noted for the presence of distinct epidermal cells that have thick, dome-like periclinal walls. Overall the ovulate organs range from 10–19 millimetres (0.39–0.75 in) by 12–17 millimetres (1.2–1.7 cm). Both the size and cell structuring is different from the livingGinkgo biloba ovulate organs, which are larger at 30 by 20 millimetres (1.18 by 0.79 in) and have less bulging periclinal walls. The stomata complexes found onG cranei ovulate organs and leaves are sparser in distribution and fewer in total number than the complexes onG. biloba.[2]