Zamites Explained

Zamites is a genus of sterile foliage known from the Mesozoic of North America, Europe, India and Antarctica through the Eocene of North America. It was erected as a form taxon for leaves that superficially resembled the extant cycad Zamia, however it is now believed to belong to a similar but phylogenetically different group, the cyacadeoids (Bennettitales).^[1] The fronds are linear or lanceolate in shape, and pinnately compound, with pinnae with parallel veins and smooth margins, and symmetrical and constricted at the base where they are attached obliquely to the upper surface of the rachis.^[2] ^[3] ^[4] It has been interpreted as a Bennettitalean plant in the family Williamsoniaceae.^[5] It is associated with the ovulate cone Williamsonia and male cone Weltrichia.^[6]

As explained by Zijlstra & van Konijnenburg-van Cittert (2020), the application of the genus name Zamites has over time drifted away from Brongniart's original concept to one where the species Z. gigas (Lindl. & Hutton) Morris has been treated as a de facto type, to the degree that none of Brongniart's four original species would now be assigned to it, instead being allocated to Otozamites and possibly elsewhere; this includes Z. bucklandii, designated as the type of Zamites by Pfeiffer in a publication dating from 1871-1875, but now (as O. bucklandii) the type of Otozamites. Technically, unless otherwise addressed, this renders Otozamites a synonym of Zamites and would mean that Z. gigas plus all the species recognisably closer to it than to Z. bucklandii would require a new genus name. Zijlstra & van Konijnenburg-van Cittert chose to attempt to circumvent this situation by proposing that Zamites should be re-defined based on designating Z. gigas as a new type to replace Z. bucklandii, a proposal that was recommended for acceptance by the Nomenclature Committee for Fossils in 2022.^[7]

Species

Species include:

Z. arcticus
Z. bayeri
Z. californica
Z. mariposana

Distribution

Fossils of Zamites have been found in:^[8]

Triassic (to Jurassic)Antarctica, Austria, China, France, Germany, Honduras, Hungary, Italy, Japan, Mexico, Romania, Tajikistan, Ukraine, and the United States (New Mexico, North Carolina, Utah, Virginia, Virginia/North Carolina).

Jurassic (to Cretaceous)Antarctica, Argentina, Azerbaijan, Belarus, Chile, China, Colombia (Valle Alto Formation, Caldas), Egypt, France, Georgia, Germany, Iran, Italy, Japan, Kazakhstan, Mexico, Mongolia, Portugal, Romania, the Russian Federation, Serbia and Montenegro, Switzerland, Tajikistan, Turkey, Ukraine, the United Kingdom, and the United States (Montana, Wyoming).

CretaceousCanada (Alberta, British Columbia), Ecuador, Japan, Mexico, South Africa, Spain, and the United States (Montana, Virginia, Wyoming).

EoceneUnited States (California)

Notes and References

Zijlstra . Gea . van Konijnenburg-van Cittert . Johanna H.A. . 2020 . (2778) Proposal to conserve the name Zamites (fossil Cycadophyta: Bennettitales) with a conserved type . Taxon . 69 . 5 . 1122–1123 . 10.1002/tax.12343. free .
Paleobotany: The Biology and Evolution of Fossil Plants (Second Edition), Thomas N. Taylor, Edith L. Taylor and Michael Krings, p. 701, 2008, .
052133344X Solnhofen: A Study in Mesozoic Palaeontology by K. Werner Barthel, Nicola Helga Margaret Swinburne and Simon Conway Morris, p. 107, 1990
0300164351 Riddle of the Feathered Dragons: Hidden Birds of China by Feduccia, Alan, p. 75, 2012
https://www.irmng.org/aphia.php?p=taxdetails&id=1381489 Zamites in IRMNG
Pott . Christian . Takimoto . Hideo . 2022-04-01 . Kimuriella gen. nov. (Bennettitales), a Whole-Plant Bennettite from the Oxfordian (Upper Jurassic) Tochikubo Formation of Shidazawa, Minamisōma, Fukushima Prefecture, Northeast Japan . Paleontological Research . 26 . 2 . 10.2517/PR200020 . 1342-8144.
Herendeen . Patrick S. . 2022 . Report of the Nomenclature Committee for Fossils: 15 . Taxon . 71 . 1 . 228–229 . 10.1002/tax.12668.
http://www.fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=54570 Zamites