New insights into the affinities, autoecology, and habit of the Mesozoic fernWeichselia reticulatabased on the revision of stems from Bernissart (Mons Basin, Belgium)

Abstract

The Mesozoic is a key period in fern evolution, with the rise of most modern families. Weichselia reticulata is a widely distributed Jurassic-Cretaceous fern that has been suggested to belong to the Matoniaceae or possibly the Marattiaceae. The most accepted classic whole-plant reconstruction for this species is based on stem and foliage material from the Barremian-Aptian locality of N egresse (Bernissart, Mons Basin, Belgium). In this work, two of these stems are revised and analysed using computed tomography, providing new information on their internal anatomy and external morphology. Weichselia reticulata has a unique anatomy, distinct from all other extant or fossil ferns. Stem external morphology suggests adaptations to stressful environments, due to the scale insertions, and a thick cortex. Especially noteworthy is the presence of structures interpreted as aerophores or nectaries at the base of putative roots and petioles that could suggest a need for extra ventilation of the frond or interactions with animals. Although these new results do not settle the question of the systematic affinities of Weichselia, they provide new information about its autoecology and allow us to test the validity of previous whole-plant reconstructions.

Quantitative plant taphonomy: the cosmopolitan Mesozoic fern Weichselia reticulata as a case study

“…2000; Blanco‐Moreno et al . 2021). It must be noted that the depositional environment for this locality is unknown, and that the material from this site has a different preservation to the other localities, all remains are preserved in 3D lignite.…”

“…Alvin 1974; Watson & Alvin 1996; Blanco‐Moreno et al . 2021). Because of its particular habitat, Weichselia reticulata has been interpreted as allochthonous in the fluvial and lacustrine environments analysed and would not have been related to the aquatic environments where it fossilized.…”

“…2001), indicating several wildfire events, which is coherent with the fire‐prone characteristics of this type of vegetation and Weichselia reticulata in particular (Blanco‐Moreno et al . 2021).…”

Taxonomic revision and palaeoecological interpretation of the plant assemblage of Bernissart (Barremian, Belgium)

“…Its affinities are, however, still a matter of debate (e.g. Silantieva and Krassilov, 2006; but see Blanco-Moreno et al, 2020). As the soral clusters have not been found in anatomical connection with the rest of the plant (Alvin, 1971;Diez et al, 2005;Silantieva and Krassilov, 2006;Sender et al, 2015) and the architectural similarities could be convergent, in this case, we have preferred to maintain it as incertae sedis.…”

Polish Palaeobotany: 750 Million Years of Plant History as Revealed in a Century of Studies. Mesozoic Macroflora

“…e first papers on this subject appeared at the beginning of the twentieth century (e.g., Scott, 1901;Stopes & Fuji, 1911). Recently, owing to modern techniques such as X-ray or computer tomography, anatomical studies have become more popular (e.g., De Beer et al, 2006;Blanco-Moreno et al, 2021;Friis et al, 2011).…”