Pterophyllum (plant)

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This article is about an extinct plant. It is not to be confused with Pterophyllum.

Pterophyllum
Temporal range: Carnian–Maastrichtian
Pterophyllum rectum - Muséum de Grenoble.jpg
Pterophyllum rectum from Muséum de Grenoble
Scientific classification e
Kingdom: Plantae
Clade: Tracheophytes
Order: †Bennettitales
Family: †Williamsoniaceae
Genus: †Pterophyllum
Type species
†Pterophyllum filicoides (Schlotheim)
René Zeiller, 1906[1]
Synonyms
  • Osmundites Jaeger 1827

Pterophyllum is an extinct form genus of leaves belonging to the Bennettitales (family Williamsoniaceae) known from the Carnian to the Maastrichtian. It contains more than 50 species, and is mainly found in Eurasia and North America.[2]

Description[]

Pterophyllum is characterized by their completely segmented leaves with leaflets having a width-length ratio of ≤2:1, at the tip of the leaf sits a terminal leaflet which can vary in shape from the rest. Its leaflets are all very similarly shaped, with no big difference from the most proximal to the most distal leaflets.[3] The plant was typically hypostomatic, meaning that its stomata are located underneath the leaf.[4]

In the Mesozoic Era, the Pterophyllum thrived and can be found in great abundance together with the rest of the Bennettitales order.[4]

Pterophyllum plants would have looked similar to modern Cycad plants which are found in a different order.[4]

Taxonomy[]

The type species for Pterophyllum is the Pterophyllum filicoides (Schlotheim), described by Zeiller in 1906.[1] The name Pterophyllum was first introduced in 1825 by Brongniart, who described two species from the Upper Triassic found in Sweden. These species were P. minus and P. majus. At this time, what now is the type species was thought to be an alga, but later Brongniart expanded his diagnosis to include more species, including the type species.[5] Later, the two originally described species were moved to the genus Anomozamites Schimper, resulting in the illegitimatization of the name. Since the name was widely used, the new type species P. filicoides (Schlotheim) Zeiller was assigned for the name to retain legitimacy.[2] Species of Pterophyllum are generally separated by the shape of their leaves as well as other features on the leaves such as vein density, anatomy of the stomata and epidermal cell shape.[4]

Difficulties in classification[]

Pterophyllum can at times be very similar to , and the need to review the diagnostics of these genera has been raised, since both genera has no distinct characteristics from one another in regards to their cuticles or epidermal cells. This means that the morphology of their leaves are the only method to differentiate between the two, where the fossil is classified as a Pterophyllum if the leaf has a length which is at least twice its width, and as an Anomozamite if it does not. This can be difficult at times, and there are several examples where plants have been erroneously placed in one genus, before being correctly placed in the other.[3]

Significance[]

Pterophyllum can be used as a proxy to reconstruct past climates using the stomatal method to estimate CO2 concentrations. Due to the similarities between Pterophyllum and Anomozamites, these can be used interchangeably to increase the amount of data. Considering the abundance of these plants during the Mesozoic era, this can be of great value for scientists reconstructing the Mesozoic climate.[4]

References[]

  1. ^ a b Zeiller, R (1906). "Bassin Houiller et Permien de Blanzy et du Creusot – Fascicule II, Flore fossile". Ministère des Travaux Publics: 265.
  2. ^ a b Gnilovskaya, Anastasia A.; Golovneva, Lina B. (February 2018). "The Late Cretaceous Pterophyllum (Bennettitales) in the North-East of Russia". Cretaceous Research. 82: 56–63. doi:10.1016/j.cretres.2017.09.013.
  3. ^ a b Pott, Christian; McLoughlin, Stephen (December 2009). "Bennettitalean foliage in the Rhaetian–Bajocian (latest Triassic–Middle Jurassic) floras of Scania, southern Sweden". Review of Palaeobotany and Palynology. 158 (1–2): 117–166. doi:10.1016/j.revpalbo.2009.08.004.
  4. ^ a b c d e Steinthorsdottir, Margret; Bacon, Karen L.; Popa, Mihai E.; Bochner, Laura; McELWAIN, Jennifer C. (July 2011). "Bennettitalean leaf cuticle fragments (here Anomozamites and Pterophyllum) can be used interchangeably in stomatal frequency-based palaeo-CO2 reconstructions: BENNETTITALEAN LEAF CUTICLES AS PALAEO-CO2 Proxies". Palaeontology. 54 (4): 867–882. doi:10.1111/j.1475-4983.2011.01060.x.
  5. ^ Pott, Christian; van Konijnenburg-van Cittert, Johanna H.A.; Kerp, Hans; Krings, Michael (December 2007). "Revision of the Pterophyllum species (Cycadophytina: Bennettitales) in the Carnian (Late Triassic) flora from Lunz, Lower Austria". Review of Palaeobotany and Palynology. 147 (1–4): 3–27. doi:10.1016/j.revpalbo.2007.03.005.
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