| What is a taphoflora? |
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A taphoflora (or floral assemblage) is the term given to all the plant fossils from one or several burials of plant remains at close stratigraphic levels, which characterize vegetation of a particular time span in a given and restricted area. See also the term 'type taphoflora'. |
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| What is a florule? |
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In the context of Alaska Smiley (1966; 1969a; 1969b; 1972a; 1972b) used the term florule to refer to individual plant fossil assemblages at a given site. It is not clear if this included a combination of several burial layers from several different sediment types or if it referred only to one burial layer. Based on its useage it is likely it refers to collections made from a single geographic location and as such may include material recovered from several different sedimentary facies and burial layers. |
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| What is a form (morphotype) identifier? |
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Unique numerical form identifiers are used when the fossil has not been formally identified. These numbers are prefixed by alphabetic characters which indicate in broad terms the main features of the leaf architecture. |
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| What is the NASR? |
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The NASR is the acronym for the Northern Alaska floral subregion. NASR |
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| What is the AKSR? |
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The AKSR is the acronym for the Anadyr-Koryak floral subregion. AKSR |
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| What is phytostratigraphy? |
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Phytostratigraphy is the recognition of regional and subregional phytostratigraphic horizons based on periodization of floral evolution. Deposits containing taphofloras of one regional or subregional phase in the development of a flora represent one horizon. |
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| What is a floral phytostratigraphic phase? |
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A phase in regional or sub-regional floral evolution is made up of one or several taphofloras of essentially similar characteristics. All taphofloras of a phase have a particular set of characteristics in common (combination of taxa, qualitative and quantitative relations between plant groups). In addition to these features in common, each taphoflora of the phase has its own specific features reflecting geographic, ecologic, and age uniqueness. Click here more information. |
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| What is a stratoflora? |
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The term ‘stratoflora’ is defined as "… general taxonomic composition of plant remains from concurrent deposits of a limited though considerable area that went through its own geological development and evolution history of organic world" (Samylina, 1974, p. 7). |
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| What is a phytostratigraphic horizon? |
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A phytostratigraphic horizon is all the coeval formations, their parts and auxiliary lithostratigraphic subdivisions, characterized by a particular plant fossil content. |
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| What did the Cretaceous Arctic forests look like? |
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A description of the forests is available here. |
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| What are formal names? |
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Where the specimen has been identified to a previously described form a formal Linnaean binomial is used. A Linnaean binomial consists, as the term 'binomial' suggests, of two parts: a genus name and a species epithet (e.g. Metasequoia occidentalis). |
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| What are informal names? |
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Morphotype identifiers or 'names' are often used when assignment to a known genus and species is problematical. They are informal, but useful, ways or refering to leaf types and are based on a system that immediately conveys something about the leaf form. |
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| What is reticulate evolution? |
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Evolution is normally thought of as having branching pattern ('tree of life'), but early in the evolution of a major group of organisms such as the flowering plants frequent hybridization results in a net-like patten instead of the usual branching. Reticulate evolution is described more fully here. |
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| What are specimen identifiers? |
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These differ depending on the origin of the material. For information on specimen identifiers click here. |
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| What are pectinal veins? |
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A pectinal vein is the lateral vein (or veins) that departs from the midvein (or another pectinal) of a leaf and supports the greatest number of subsidiary branches abmedially. Click here for more information. |
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| How are leaf tooth types classified? |
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Tooth classification in this work is based on Hickey and Wolfe (1975). The different tooth types are described here. |
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| How did the Arctic region evolve during the Cretaceous? |
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In the early part of the Late Cretaceous plate movements eliminated the deep water connection to the Pacific and the Arctic Ocean remained relatively enclosed and isolated from the rest of the world's oceans throughout the the Late Cretaceous and well into the Paleogene. For maps showing the changes in the Arctic Ocean geometry during the Cretaceous click here. |
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| What was the Cretaceous Arctic light regime? |
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There is no evidence to suggest that during the Cretaceous the Earth's obliquity was significantly different to that of the present day. This, backed up by evidence from tree rings, suggests that we can use the modern light regime as a guide to the past. |
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| Why are the high resolution images overprinted? |
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This is because we want to encourage researchers to examine the actual specimens rather than just the photographs. By overprinting we prevent the images being used in third party publications without proper study of the material. |
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| Why are some names in quotes? |
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In the older literature fossil leaves are often given the names of modern plants without any real justification other than the leaves look like the modern ones. This is not really very satisfactory because we have no idea what the associated flowers, seeds or pollen were like. In these cases we put the modern names in quotes to indicate that they should not be regarded as indicating the modern plants were present in the Cretaceous or Paleogene. |
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| What do 'ex gr.', 'aff.', and 'cf.' etc. mean? |
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These are qualifiers that indicate the precision of our formal identifications. For more details click here. |
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| Why do some floras on the correlation charts have no active links to additional information and fossil images? |
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All the floras and/or phytostratigraphic phases have been described in the literature. However not all the collections have been photographed by us, in some cases because the collections were deposited in regional museums and are not accessible (for example in remote parts of Northeastern Russia) or have been lost. |
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