Eostangeria

Eostangeria is a morphogenus of fossil foliage belonging to the Cycadales.

Eostangeria
Temporal range:
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Gymnosperms
Division: Cycadophyta
Class: Cycadopsida
Order: Cycadales
Family: Zamiaceae
Subfamily: Eostangerioideae
Kvaček, Palamarev & Uzunova, 2002[1]
Genus: Eostangeria
Barthel, 1976[2]
Type species
E. saxonica
Barthel, 1976
Other species
  • E. pseudopteris
    Kvaček & Manchester, 1999
  • E. ruzinciniana
    (Palamarev, Petkova, & Uzunova) Palamarev & Usunova, 1992

Taxonomy

Some leaflets of Eostangeria had previously described as ferns such as Angiopteris. As late as 1999 there was uncertainty regarding the familial affinities of the genus, with suggested relationship to with either Stangeria or the Colombian Zamia restrepoi. However with the redescription of E. ruzinciniana by Uzunova, Palamarev, and Kvacek (2002) the genus was placed in the cycad family Zamiaceae as the type genus of the monotypic subfamily Eostangerioideae.[1]

Distribution

Eostangeria was first described based on material E. saxonica from the Eocene of the Geisel valley,[3]. Subsequently E. ruzinciniana was described from the Middle Miocene Krivodol Formation of Bulgaria,[1] while E. pseudopteris was detailed from Paleocene through Eocene sediments in Western North America including Wyoming and Oregon.[4]

Description

Leaflets of Eostangeria have a notable midrib from which parallel veins diverge fusing only rarely in the margin of the leaflet. Dispersed leaflets are often retrieved, suggesting the presence of an abscission layer at the base.[4] Cuticles have isodiametrical to elongated cells, with dark-staining and light-staining pavement cells and sunken stomata. If the cuticle is not preserved, leaflets of Eostangeria can be confused with fern leaflets of the genus Allantodiopsis.[4]

References

  1. Uzunova, K.; Palamarev, E.; Kvaček, Z. (2002). "Eostangeria ruzinciniana (Zamiaceae) from the Middle Miocene of Bulgaria and its relationship to similar taxa of fossil Eostangeria, and extant Chigua and Stangeria (Cycadales)". Acta Palaeobotanica. 41 (2): 177-194.
  2. Barthel, M (1976). Eozäne Floren des Geiseltales: Farne und Cycadeen. Abhandlungen des Zentralen Geologischen Institutes. Paläontol Ab-handl.
  3. Barthel, M (1976). Eozäne Floren des Geiseltales: Farne und Cycadeen. Abhandlungen des Zentralen Geologischen Institutes. Paläontol Ab-handl.
  4. Kvaček, Z.; Manchester, S.R. (1999-05-01). "Eostangeria Barthel (Extinct Cycadales) from the Paleogene of Western North America and Europe". International Journal of Plant Sciences. 160 (3): 621–629. doi:10.1086/314152. ISSN 1058-5893. JSTOR 10.1086/314152. S2CID 83978433.


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