''Paradinandra'' is a genus of

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

plants from the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

Sweden Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...

. Its only species is ''Paradinandra suecica''. The genus and species were described in 2001 and given an uncertain family placement within the order

Ericales The Ericales are a large and diverse order of flowering plants in the asterid group of the eudicots. Well-known and economically important members of this order include tea and ornamental camellias, persimmon, ebony, blueberry, cranberry, l ...

Description

The flowers of ''P. suecica'' are less than long, which is typical for fossil flowers from the Cretaceous. The flowers are organised into whorls of five parts. The

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 Etymology The term ''sepalum'' ...

s are free,

lanceolate The following terms are used to describe leaf plant morphology, morphology in the description and taxonomy (biology), taxonomy of plants. Leaves may be simple (that is, the leaf blade or 'lamina' is undivided) or compound (that is, the leaf blade ...

, and have as obtuse tip. They bear

trichome Trichomes (; ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a plant ...

s along the median

vein Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and feta ...

, and become much thinner away from the thickened centre. The

petal Petals are modified leaves that form an inner whorl surrounding the reproductive parts of flowers. They are often brightly coloured or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corol ...

s are thought to be fused together, at least at their bases; they are shaped like a bishop's mitre. Each flower has 15

stamen The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

s, which may also be united at the base, and taper towards the attachment of the anther. The filaments of the outer whorl of five stamens are long, while those of the inner whorl are around either or long. This results in the anthers falling into three distinct layers in the bud. It is not known whether the difference is retained on flowering. Pollen grains found associated with the flowers are long, and appear to be tricolpate, which is a characteristic of the

eudicots The eudicots or eudicotyledons are flowering plants that have two seed leaves (cotyledons) upon germination. The term derives from ''dicotyledon'' (etymologically, ''eu'' = true; ''di'' = two; ''cotyledon'' = seed leaf). Historically, authors h ...

. The

gynoecium Gynoecium (; ; : gynoecia) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl (botany), whorl of a flower; it consists ...

bears three styles, and the ovules are curved.

Biostratigraphy

The specimens of ''Paradinandra'' had been naturally fusainised (turned into

charcoal Charcoal is a lightweight black carbon residue produced by strongly heating wood (or other animal and plant materials) in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, ca ...

), and were recovered by sieving sand and clay. The deposits are thought to be of Late

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 m ...

to Early

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

age, and are located in a former

kaolin Kaolinite ( ; also called kaolin) is a clay mineral, with the chemical composition Al2 Si2 O5( OH)4. It is a layered silicate mineral, with one tetrahedral sheet of silica () linked through oxygen atoms to one octahedral sheet of alumina (). ...

quarry A quarry is a type of open-pit mining, open-pit mine in which dimension stone, rock (geology), rock, construction aggregate, riprap, sand, gravel, or slate is excavated from the ground. The operation of quarries is regulated in some juri ...

owned by Höganäs AB near Näsum,

Skåne Scania ( ), also known by its native name of Skåne (), is the southernmost of the historical provinces of Sweden, provinces () of Sweden. Located in the south tip of the geographical region of Götaland, the province is roughly conterminous w ...

(). The specimens were described by Jürg Schöneberger and Else Marie Friis in 2001 in the ''

American Journal of Botany The ''American Journal of Botany'' is a monthly peer-reviewed scientific journal which covers all aspects of plant biology. It has been published by the Botanical Society of America since 1914. The journal has an impact factor of 3.038, as of 20 ...

'', and have been deposited at the Swedish Museum of Natural History.

Taxonomy

In their original

description Description is any type of communication that aims to make vivid a place, object, person, group, or other physical entity. It is one of four rhetorical modes (also known as ''modes of discourse''), along with exposition, argumentation, and narr ...

, Schöneberger and Friis noted that the flowers had few features which would allow them to determine the relationships of ''Paradinandra'' to other plants. The stamen arrangement seen in ''Paradinandra'' and the curved ovules are both seen in various families within the

('' sensu lato''), and some families, such as Ternstroemiaceae (now included in Pentaphylacaceae), show both. This suggests that closest relatives of ''Paradinandra'' are found among the order Ericales, but the authors could not assign the fossil to any single family, and therefore assigned it ''

incertae sedis or is a term used for a taxonomy (biology), taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...

'' (of uncertain placement) within the order. A 2020 phylogenetic analysis of a wide range of fossil angiosperm flowers found that ''P. suecica'' could be part of an early lineage of Ericales that might have become extinct later. However, its floral features were also found in some other eudicot clades, and it could also be placed outside Ericales in the analysis.

Description

Biostratigraphy

Taxonomy

References

Further reading