In Situ spores of Marattialean ferns from the Late Triassic of Europe

1. In situ spores of marattialean ferns from the Late
Triassic of Austria, Switzerland, and Sweden
1
Museum of Nature South Tyrol, Bozen/Bolzano, Italy; hendrik.nowak@naturmuseum.it
2
Department für Geo- und Umweltwissenschaften, Paläontologie und Geobiologie,
Ludwig-Maximilians-Universität, München, Germany
3
Bayerische Staatssammlung für Paläontologie und Geobiologie, München, Germany
4
Naturalis Biodiversity Center, Leiden, the Netherlands;
5
Laboratory of Palaeobotany and Palynology, Utrecht, the Netherlands
6
Istituto di Geoscienze e Georisorse - CNR, Padova, Italy
Hendrik Nowak1
, Evelyn Kustatscher1,2,3
,
Johanna H. A. Van Konijnenburg-van Cittert4,5
, Guido Roghi6

2. Marattiales
● Or: Marattioid ferns
● Eusporangiate = sporangia develop from multiple epidermal cells
● Usually large fronds
● First occurrence in the Carboniferous
● Common in Late Triassic palaeofloras
● One extant family (Marattiaceae), six extant genera
3 cm
Asterotheca arborescens
Pennsylvanian (Taylor et al., 2009)
1 cm
Asterotheca merianii
Middle–Late Triassic
© Coley Chang

3. Materials
Lunz am See, Austria
Carnian (early Late Triassic)
commons.wikimedia.org
Neuewelt, Switzerland
Carnian (early Late Triassic)
Billesholm, Sweden
Rhaetian (latest Triassic)

4. Methods
Manual extraction of sporangia/sori
& Maceration via Schultze method
using HNO3 + KClO3, KOH
Where possible, multiple samples were taken
from a specimen at different positions
Isolation of spores
& Mounting in glycerin jelly

5. 200 µm
20 µm
20 µm
1 cm
Asterotheca merianii (Brongniart) Stur ex Krasser, 1909
● Common in Middle–Late Triassic floras
● Locality: Lunz am See, Austria
● Stratigraphy: Lunz Formation, Carnian
● In situ spores:
● Circular to slightly oval; 29–50 µm
● Monolete or pseudotrilete/triletoid
● Smooth or microverrucate surface
● Significant variation in size and aperture
within sporangia, but ornamentation
consistent across frond
● Previous descriptions: Nathorst (1908);
Bharadwaj & Singh (1956); Potonié (1962,
1967); Andrews in Boureau (1970); Balme
(1995); Kustatscher & Van Konijnenburg-van
Cittert (2011); Pott et al. (2018)

6. Merianopteris augusta Heer, 1877
1 cm
20 µm
20 µm
50 µm
● Has long been considered a junior synonym of
A. merianii
● Locality: Neuewelt, Münchenstein, Switzerland
● Stratigraphy: Klettgau Formation, Carnian
● In situ spores:
● Approx. circular; 52–74 µm
● Trilete, often indistinct mark
● Verrucate to vermiculate ornamentation
● No previous description of in situ spores

7. Mertensides bullatus (Bunbury) Fontaine, 1883
1 cm
20 µm
20 µm
100 µm
● Locality: Lunz am See, Austria
● Stratigraphy: Lunz Formation, Carnian
● In situ spores:
● Circular to slightly oval; 32–49 µm
● Monolete or pseudotrilete/triletoid
● Smooth or scabrate (microechinate acc. to
Pott et al., 2018) surface ornamentation
● Previous description: Pott et al. (2018)

8. Danaeopsis marantacea (Presl) Schimper, 1869
1 cm 100 µm
20 µm 20 µm
● Type species of Danaeopsis; especially common
in the Ladinian of the Germanic Basin
● Locality: Neuewelt, Münchenstein, Switzerland
● Stratigraphy: Klettgau Formation, Carnian
● In situ spores:
● Approx. circular; 49–63 µm
● Trilete, sometimes one ray slightly shorter
● Smooth surface
● Previous description: Kustatscher & Van
Konijnenburg-van Cittert (2011); Kustatscher
et al. (2012)

9. Danaeopsis lunzensis Stur ex Kustatscher et al., 2012
1 cm
20 µm
● Locality: Lunz am See, Austria
● Stratigraphy: Lunz Formation, Carnian
● In situ spores:
● Approx. circular; 53–71 µm
● Trilete, often one ray shorter or longer
● Smooth surface (or microreticulate
ornamentation acc. to Kustatscher et al.,
2012)
● Previous descriptions: Nathorst (1908);
Potonié (1962, 1967); Balme (1995);
Kustatscher et al. (2012); Pott et al. (2018)
50 µm
20 µm
20 µm

10. Danaeopsis fecunda Halle, 1921
1 cm
20 µm
● Locality: Billesholm, Sweden
● Stratigraphy: Höganäs Formation, Rhaetian
● In situ spores:
● Approx. circular, 61–73 µm
● Trilete, often one ray shorter or longer
● Smooth or microreticulate surface
ornamentation
● Previous description of in situ spores: Halle
(1921); Potonié (1962, 1967); Balme (1995);
Taylor et al. (2009); Kustatscher et al. (2012)
20 µm
100 µm

11. Comparison
● Asterotheca merianii and Mertensides bullatus:
● Both monolete to triletoid, similar sizes
● Spores of M. bullatus sometimes with more
pronounced ornamentation
● Comparable dispersed genus: Leschikisporis
● Spores of Merianopteris augusta differ in size,
aperture, and ornamentation
➔ supports taxonomic distinction from A.
merianii
● Comparable to Verrucosisporites
20 µm
20 µm
20 µm
20 µm
Merianopteris augusta
Asterotheca merianii
Mertensides bullatus

12. Comparison
● Danaeopsis spp.:
● Similarly smooth or scabrate, with a trilete or
triletoid mark
● Size ranges different, but overlapping;
on average:
D. marantacea < D. lunzensis < D. fecunda
● Spores of D. marantacea typically with more
equal rays, D. lunzensis often one longer ray
● Microreticulate ornamentation here only
seen in D. fecunda, but also reported from D.
lunzensis by Kustatscher et al. (2012)
● Comparable to Todisporites (trilete) or
Leschikisporis (triletoid)
20 µm
Danaeopsis fecunda
Danaeopsis marantacea
20 µm
20 µm
20 µm
Danaeopsis lunzensis
20 µm

13. Abortive spores
20 µm
Asterotheca merianii
● Considerably smaller, often darker, strongly
wrinkled compared to regular spores
● Appear to be compressed from all sides; in
contrast to normally compressed (flattened,
folded, pinched) spores
● Interpreted as abortive (not well-developed)
● Usually small amount in sufficiently rich
samples, but higher frequency in some
specimens
● Higher amounts of abortive spores could
indicate pathologies, ecological stress, or
(natural) hybridisation
20 µm
20 µm
20 µm
Danaeopsis marantacea

14. Conclusions
● Spore wall ornamentation is relatively consistent for individual specimens but can differ
between individuals
➔ Probably mostly representing different stages of maturation
➔ + preservational and/or other effects?
● Spores of Danaeopsis are generally similar
● Trilete mark often with rays of unequal length
● Differences in average sizes, ornamentation, and details of the trilete mark
● Spores of Merianopteris augusta differ from others in having a coarse ornamentation
➔ Supports taxonomic distinction from Asterotheca merianii
● Abortive spores occur with increased frequency in some specimens
➔ May indicate abnormal states or hybridisation

15. References & Acknowledgements

Boureau, É. (Ed.), 1970. Traité de paléobotanique, IV (1): Filicophyta. Masson, Paris.

Halle, T.G., 1921. On the sporangia of some Mesozoic ferns. Arkiv för Botanik 17, 1–28.

Kustatscher, E., Kelber, K.-P., van Konijnenburg-van Cittert, J.H.A., 2012. Danaeopsis Heer ex Schimper 1869 and its
European Triassic species. Review of Palaeobotany and Palynology 183, 32–49.

Kustatscher, E., Van Konijnenburg-Van Cittert, J.H.A., 2011. The ferns of the Middle Triassic flora from Thale (Germany). N. J.b.
Geol. Paläontol. Abh. 261, 209–248.

Nathorst, A.G., 1908. Paläobotanische Mitteilungen 4–6. Kungl. Svenska Vetenskapsakademiens Handlingar 43, 1–33.

Potonié, R., 1962. Synopsis der Sporae in situ. Die Sporen der fossilen Fruktifikationen (Thallophyta bis Gymnospermophyta)
im natürlichen System und im Vergleich mit den Sporae dispersae, Beihefte zum Geologischen Jahrbuch. Bundesanstalt für
Bodenforschung, Hannover.

Potonié, R., 1967. Versuch der Einordnung der fossilen Sporae dispersae in das phylogenetische System der Pflanzenfamilien,
Forschungsberichte des Landes Nordrhein-Westfalen. Westdeutscher Verlag, Köln, Opladen.

Pott, C., Bouchal, J.M., Choo, T.Y.S., Yousif, R., Bomfleur, B., 2018. Ferns and fern allies from the Carnian (Upper Triassic) of
Lunz am See, Lower Austria: A melting pot of Mesozoic fern vegetation. Palaeontographica Abteilung B 297, 1–101.

Taylor, T.N., Taylor, E.L., Krings, M., 2009. Paleobotany: the biology and evolution of fossil plants, 2. ed. Elsevier/Acad. Press,
Amsterdam.
This study was funded by the Forschungsfonds der Landesmuseen of the Bozen-Bolzano province as part of the
project “MAMPFT - Mikrosporen An MakroPflanzen-Fossilien der Trias”.
This research received support from the SYNTHESYS+ Project
http://www.synthesys.info/ which is financed by European Community Research
Infrastructure Action under the H2020 Program (AT-TAF-2451; DE-TAF-2452).