Differentiation of the fossil leaves assigned to Taeniopteris, Nilssoniopteris and Nilssonia with a comparison to similar genera (original) (raw)

Elsevier

Review of Palaeobotany and Palynology

Highlights

Abstract

Taeniopterid leaves are characterized by an entire margin and a midrib with secondary veins that may or may not bifurcate. This artificial group contains leaves that belong to ferns or, mainly cycadophyte, gymnosperms. If cuticle or reproductive structures are present, the leaves can be placed in natural groups and genera, such as Nilssonia and Nilssoniopteris. If not, they are placed in the fossil-genus Taeniopteris. However, nomenclatorial issues around these genera were complicated and most have only recently been solved. Here we briefly describe and differentiate between these three genera, including diagnoses and type species, all of which are figured. Other, similar but less well known or not often used genera are briefly discussed as well. Moreover we provide taxonomic keys to help determine the generic affiliation of such fossils.

Introduction

Fossil sterile leaves with an entire margin, a midrib and secondary veins that may or may not be bifurcated are generally united in a larger group of sterile leaves commonly called Taeniopterides (or taeniopterids). This group contains leaves that belonged either to certain ferns (Marattiales) or to mainly cycadophyte gymnosperms (Cycadales, Bennettitales) and includes fossils of both Mesozoic and Palaeozoic age. If cuticle and/or reproductive structures are preserved, the fossils can usually be placed easily in these taxonomic groups. However, impression fossils of such leaves can be difficult to assign, although venation patterns may help (e.g., differentiation between the fern and cycadophyte leaves).

In the past, various genera have been used for such leaves (e.g., Taeniopteris, Taeniozamites, Nilssoniopteris, Nilssonia) but the nomenclatorial issues surrounding these generic names are often complicated and have remained unresolved. Several authors have misidentified their specimens, placed them in the wrong genera or indicated incorrect types for the generic names. All of these genera and their typifications have been recently discussed, and some proposals for conservation made (Gomolitzky, 1987, Cleal and Rees, 2003, Cleal et al., 2006, Zijlstra, 2016, Zijlstra et al., 2016), but the complicated nomenclatural history is still causing confusion among palaeobotanists. In this paper we will, therefore, briefly describe and differentiate between these genera, and provide taxonomic keys to help determine the generic affiliation of such fossils.

Section snippets

Material and methods

We briefly explain the typification of the various genera from the literature, their diagnoses (as published and emended), type specimens (providing, if possible, new photos of the holotypes and, when present, illustrations of the epidermal and cuticular characteristics). We also provide a very short history and discussion of each genus.

In our discussions we use the term ‘midrib’ rather than midvein or rachis, but when citing diagnoses we do not replace those words. The same applies to the use

Taeniopteris Brongniart, 1828 nom. cons. prop.

Diagnosis (as emended by Cleal and Rees, 2003): “Leaves with a simple, entire-margined lamina. Midvein rigid, extending for entire length of leaf. Lateral veins approximately perpendicular to midvein, simple or forking at base. Evidence of epidermal structure not known”.

Type: In order to allow the name to continue to be used for leaves un-attributable to one of the major plant groups, Zijlstra et al. (2016) proposed to conserve the generic name Taeniopteris Brongniart, 1828 (p. 61) and its type

Differentiating key for some common taeniopterid leaves

This paper is dealing with various types of taeniopterid leaves. To distinguish between them, we here provide a simple differentiating key (Table 1). The key is only informal and in many cases, a cuticle sample is inevitable for further discrimination (see Table 2).

A more elaborate key can be found in Table 2. Samylina (1956) also provided a key for taeniopterid leaves, but this key contained fewer genera than the present one, and is, in addition, published exclusively in Russian, a language

Conclusions

The present paper is a good example for using a ‘fossil-taxon’ such as Taeniopteris in terms of the International Code of Nomenclature (McNeill et al., 2012). Fossil leaves can easily be placed in this fossil taxon, when their gross-morphology (including venation) is known, but more details such as presence of sporangia and information on epidermal anatomy are unavailable. However, if the latter information is available, their attribution to a natural group of plants, such as ferns, cycads or

Acknowledgements

We want to thank Pat Herendeen for his advice on nomenclatural issues and his review of the paper, just as we are thankful to an anonymous reviewer.

References (48)

Rev. Palaeobot. Palynol.

(1983)

Bennettitalean foliage in the Rhaetian–Bajocian (latest Triassic–Middle Jurassic) floras of Scania, southern Sweden

Rev. Palaeobot. Palynol.

(2009)

Bennettitales in the Rhaetian flora of Wüstenwelsberg, Bavaria, Germany

Rev. Palaeobot. Palynol.

(2016)

Proposal to conserve the name Nilssonia with that spelling (fossil Cycadopsida, Nilssoniaceae)

Taxon

(2011)

Flora of the Shemshak Formation (Elburz, Iran), Pt.3: Middle Jurassic (Dogger) Plants from Katumbargah, Vasek Gah and Imam Manak

Palaeontogr. Abt. B

(1976)

Epidermisuntersuchungen an einigen inkohlten Pteridospermen-blättern des Oberkarbons und Perms

Geologie

(1962)

Die Rotliegendflora des Thüringer Waldes. Teil 4: Farnsamer und Farnlaub unbekannter taxonomischer Stellung

Veröff. Naturhist. Mus. Schleusingen

(2006)

Neue Funde fossiler Pflanzen aus dem Saale-Trog

Wissensch. Zeitschr. Humboldt-Univ.; Berlin, Math.-Nat.

(1975)

Bennettitales from Early Cretaceous floras of West Greenland: Pterophyllum and Nilssoniopteris

Palaeontogr. Abt. B

(2000)

Observations sur les végétaux fossiles renfermé dans les Grès de Hoer en Scanie

Ann. Sci. Nat.

(1825)

Prodrome d'une histoire des végétaux fossiles

(1828)

Histoire des végétaux fossiles, ou, Recherches botaniques et géologiques sur les végétaux renfermés dans les diverses couches du globe. Part 5–6

(1831)

Lethaea Geognostica oder Abbildungen und Beschreibungen der für die Gebirgs-Formationen bezeichnendsten Versteinerungen. 1. der Übergangs- bis Oolithen-Gebirge enthaltend

(1835)

The Middle Jurassic flora from Stonesfield, Oxfordshire, UK

Palaeontology

(2003)

A clarification of the type of Nilssoniopteris Nathorst (fossil Gymnospermophyta, Bennettitales)

Taxon

(2006)

Mesozoic and Tertiary palaeobotany of Great Britain

Studien über die Cycadales des Mesozoikums

K. Sven. Vetensk. Akad. Handl

(1933)

Über Nilssoniopteris glandulosa n. sp., eine Bennettitacee aus der Juraformation Bornholms

Ark. Bot.

(1934)

La flora Triásica del grupo El Tranquilo, Provincia de Santa Cruz, Patagonia

Proposal to conserve Nilssoniopteris against Taeniozamites (Fossiles)

Taxon

(1987)

The Rhaetic flora of Scoresby Sound, East Greenland

Medd. Grønland

(1926)

The fossil flora of Scoresby Sound East Greenland – part 2: description of seed plants incertae sedis together with a discussion of certain cycadophyte cuticles

Medd. Grønland

(1932)

The fossil flora of Scoresby Sound East Greenland – part 3: Caytoniales and Bennettitales

Medd. Grønland

(1932)

The Yorkshire Jurassic Flora, II. Cycadales

(1964)

Cited by (26)

2018, Review of Palaeobotany and Palynology
2007 Ptilozamites heeri Nathorst—Kustatscher and Van Konijnenburg-van Cittert, p. 73, text-figs. 1A–L. Van Konijnenburg-van Cittert et al., 2017 Ptilozamites heeri Nathorst—Van Konijnenburg-van Cittert et al., p. 148, text-figs. 4A, B. Description: The longest frond fragment found at Wüstenwelsberg is up to 72 mm long and 17 mm wide (incomplete frond fragment, specimen UU23269A). View all citing articles on Scopus

View full text

© 2016 Elsevier B.V. All rights reserved.