Paradinandra

Paradinandra suecica is a species of fossil plant from the Cretaceous of Sweden. It is of uncertain placement within the order Ericales, and was described in 2001.

Biostratigraphy

The specimens of Paradinandra had been naturally fusanised (turned into charcoal), and were recovered by sieving sand and clay. The deposits are thought to be of Late Santonian to Early Campanian age, and are located in a former kaolin quarry owned by Höganäs AB near Näsum, Skåne, Sweden (56°9′N 14°30′E / 56.150°N 14.500°E / 56.150; 14.500). The specimens were described by Jürg Schöneberger and Else Marie Friis in 2001 in the American Journal of Botany, and have been deposited at the Swedish Museum of Natural History.

Description

The flowers of P. suecica are less than 3.5 millimetres (0.14 in) long, which is typical for fossil flowers from the Cretaceous. The flowers are organised into whorls of five parts. The sepals are free, lanceolate, and have as obtuse tip. They bear trichomes along the median vein, and become much thinner away from the thickened centre. The petals are thought to be fused together, at least at their bases; they are shaped like a bishop's mitre. Each flower has 15 stamens, 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 0.75 mm (0.030 in) long, while those of the inner whorl are around either 0.45 mm (0.018 in) or 0.55 mm (0.022 in) 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 10–14 micrometres (0.00039–0.00055 in) long, and appear to be tricolpate, which is a characteristic of the eudicots. The gynoecium bears three styles, and the ovules are curved.

Affinities

In their original description, 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 Ericales (sensu lato), and some families, such as Ternstroemiaceae, 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 (of uncertain placement) within the order.

References

• Jürg Schönenberger & Else Marie Friis (2001). "Fossil flowers of ericalean affinity from the Late Cretaceous of Southern Sweden". American Journal of Botany. 88 (3): 467–480. doi:10.2307/2657112. PMID 11250825. 

Further reading

• Jürg Schönenberger (2005). "Rise from the ashes – the reconstruction of charcoal fossil flowers". Trends in Plant Science. 10 (9): 436–443. doi:10.1016/j.tplants.2005.07.006. PMID 16054859.