Schmeissneria
| Schmeissneria | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Temporal occurrence | ||||||||||||
| Lower Jurassic ( Hettangium ) to Middle Jurassic | ||||||||||||
| 200 to 161 million years | ||||||||||||
| Locations | ||||||||||||
|
Germany, China |
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| Systematics | ||||||||||||
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| Scientific name of the family | ||||||||||||
| Schmeissneriaceae | ||||||||||||
| Zhou | ||||||||||||
| Scientific name of the genus | ||||||||||||
| Schmeissneria | ||||||||||||
| Kirchner & Van Konijnenburg-van Cittert | ||||||||||||
Schmeissneria is an extinct relative of the ginkgo and the only genus in the Schmeissneriaceae family.
features
The genus differs from the other representatives of the Ginkgoales in the following features: The fertile shoots carry single or paired cupules in a spiral arrangement , which can be seated or stalked. The seeds are winged to maturity.
The seed-bearing axes are up to 8 cm long and have up to 45 teardrop-shaped cupules. Each of them is up to 3.5 mm long. At maturity the seeds are up to 5 mm long.
Short and long bars are formed. The leaves are undivided and sessile.
Together with Schmeissneria microstachys , pollen organs of the Stachyopitys preslii type are found and should belong to the same plant.
distribution
The genus Schmeissneria is known from the Hettangian ( Lower Jurassic ) of Germany and the Middle Jura, probably Callovian , from Liaoning in northeast China.
Systematics
The genus Schmeissneria was established in 1994 for the type species Schmeissneria microstachys by Kirchner and Van Konijnenburgvan Cittert. In 1997 the genus was placed in its own family Schmeissneriaceae. She was interpreted as a representative of the Ginkgoales . However, some features also place them close to the Gnetophyta .
After the discovery of Schmeissneria sinensis in the Haifanggou Formation in Liaoning, an affinity for the angiosperms was discussed. In this species, the ovules and cupules are paired on short stalks along an axis. Each of the ovules has a central unit, which is surrounded by a shell with characteristic longitudinal ribs. The top is completely closed by a wall. Each central unit has two compartments which are completely separated from each other by a vertical septum.
supporting documents
- Zhi-Yan Zhou: An overview of fossil Ginkgoales. In: Palaeoworld. Volume 18, No. 1, 2009, pp. 1–22, doi: 10.1016 / j.palwor.2009.01.001 .
- Thomas N. Taylor, Edith L. Taylor, Michael Krings: Paleobotany. The Biology and Evolution of Fossil Plants. 2nd Edition. Academic Press, Amsterdam et al. 2009, ISBN 978-0-12-373972-8 , p. 753.