Systematics

Introduction

The naming of plant fossils is both complicated and confused. It is complicated because plants are never preserved as whole entities. Leaves, pollen, flowers and seeds are all shed from the parent plant throughout its life and these separate parts become fossilised in isolation. As a consequence paleobotanists are denied the complete suite of characters necessary to identify complete plants. In addition the preservation of characters is never perfect. In some cases cellular detail may survive in others just the bearest of outlines of the whole organ (e.g. a leaf shape). These factors introduce a great deal of uncertainty into identification and the correct naming of plant fossils.

This uncertainty has generated considerable confusion over the years. The authors of older literature understandably tended to compare whatever features were preserved with living plant parts. There were few protocols for doing this in a consistent manner and a culture of 'picture matching' evolved even to the extent that the names of living (extant) genera, and sometimes even species, were applied to the fossil remains on the flimsiest of similarities. In turn this lead to the idea that many genera and species were of great antiquity, something that is highly unlikely given what we now know about evolutionary processes and the considerable changes in geography and climate that have occurred over time. The use of names of living taxa does not necessarily indicate that the fossils actually represent those living taxa.

Under the International Code of Nomenclature for Algae, Fungi and Plants first used names have priority unless there are good reasons for changing them. Detailed study is required to amass the appropriate evidence for making such changes. There are far too few specialists engaged in such work and as a result the paleoebotanical literature is littered with inappropriate names for plant parts, particularly leaves, which naturally show a range of variation more allied to environmental adaptation than genetic lineage. Flowers, pollen and seeds tend to be architecturally more stable irrespective of environment and thus a better indicator of genetic relationship, but in the case of fossil material these are rarely attached to leaves or any other vegetative parts of the parent plant.

The purpose of this catalogue is to put images of Arctic plant fossil material into the public domain. It is not to undertake a comprehensive revision of Arctic Cretaceous and Paleogene plant nomenclature or taxonomy.

Consequently the names used should be regarded merely as labels to indicate a particular form within the limits imposed by preservation. Because the individual fossils are variously preserved and are rarely complete there are varying degrees of uncertainty in applying such names. Many of the names used in the older literature relate directly to those of living plants, most often at the genus level (e.g. Alnus, Tilia, Menispermum, Quercus, Ziziphus etc.). Such names should not be taken to indicate that plants identical to those alive today existed in the Cretaceous or Paleoegene. However because we deliberately choose not to undertake a revision of the nomenclature these old names appear in this catalogue alongside more appropriate names that are unique to the fossil remains (e.g. Alnites, Tiliaephyllum, Menispermites, Quercophyllum, Ziziphoides etc.).