Fossil ferns

The Pennsylvanian filicalean fern Kaplanopteris clavata gen. et comb. nov. is reconstructed on the basis of permineralized vegetative and fertile frond segments and rhizomes. Characteristic anatomy conforming to morphospecies Anachoropteris clavata Graham allows for integration of new observations and reevaluation of material from Ohio with published data into the whole-plant reconstruction. Epiphyllous rhizomes arise laterally along frond rachides and feature terete exarch protosteles. Fronds are planar, tripinnate-pinnatifid, with alternate division. Vascular traces of all frond members have adaxial, exarch protoxylem. Rachides and primary pinnae
have adaxially convex C-shaped traces; secondary pinna traces are terete. Pinnules are laminar, with lobed margins and open dichotomous venation. Tripinnate latent croziers equivalent in complexity to whole fronds arise on otherwise mature frond segments at the position of primary pinnae. Superficial abaxial indusiate sori exhibit gradate maturation and include numerous leptosporangia producing trilete spores. Sporangial capsules are bent away from the center of the sorus at the juncture with the long, uniseriate stalks. The annulus is a band of two to three rows of interfingering cells, wrapped around the long axis of the sporangium and covering most of it. The longitudinal stomium faces toward the apex of the sorus. Kaplanopteris clavata is reconstructed as a primarily vining plant with organography overwhelmingly dominated by the frond and a unique life-history pattern influenced by growth from two types of foliar-borne reiterative units: latent croziers and rhizomes. Kaplanopteris combines characters known exclusively in fossil filicaleans with both plesiomorphic and derived characters of living filicaleans. This novel combination reveals the existence of a previously unrecognized lineage
of basal filicaleans and justifies placement in a new family. Kaplanopteris illustrates the diversity and complexity reached during the first major evolutionary radiation of filicaleans.

The two species currently recognized within the enigmatic
genus Knorripteris raise two major questions: (1) Are these
plants ferns? (2) How do we interpret their unusual stelar
organization? We suggest that, with the exception of the
reverse orientation of the protoxylem in leaf traces, most
features of Knorripteris correspond more or less well with
features seen in other fossil and extant ferns. Although we
only know the erect leafy shoots in the form of the permineralized
Knorripteris stem portions, it is reasonable to
assume that the Knorripteris plant had a growth habit
similar to that reconstructed for Todites princeps, that is,
with a prostrate rhizome bearing roots and erect, leafy
shoots. The leafy shoot (¼Knorripteris) is characterized by
a cauline phloem, while the xylem is entirely foliar,
resulting in a very unusual stelar organization. Rhizomes of
the same plant probably had significantly different anatomy,
perhaps with marked cauline characteristics more
closely corresponding to the stelar types traditionally
known in ferns. Unfortunately, this will remain a hypothesis
until axes bearing Knorripteris leafy shoots remain
unknown, or as long as a permineralized Todites fern is not
described. Coming back to the original question regarding
“is Knorripteris a fern or not a fern?”dit is most likely a
ferndbut until additional material is found, this is still the
question.

The 200th anniversary of the discovery of the silicified tree fern Tubicaulis solenites has provided an opportunity to examine the discovery and long-term collection history of this fossil, and to cast light on the location of the various fragments into which the specimen had been cut. So far, the species has been recorded only from the Gückelsberg quarry at Flöha (Germany). During the investigations it emerged that parts of the original specimen had been distributed to several collections worldwide; after almost two years of research, we can say that several fragments of this find are identifiable in European collections and beyond. This study of T. solenites aims to contribute to the history of European natural science in the late nineteenth and early twentieth centuries, by exploring an extensive network of local and professional collectors that has existed since the time of its discovery.

The 200th anniversary of the discovery of the silicified tree fern Tubicaulis solenites provides an opportunity to examine the long discovery- and collection history of this fossil, and to document the storage of the various fragments, into which the specimen has been cut; including a short biographical note about its finder, H.A.L. Schippan. Until now this unique fossil fern was only known from the Gückelsberg quarry at Flöha. During the investigations it turned out that parts of the specimen were distributed to several collections worldwide.
Still accessible parts are described and illustrated. Since reasonable doubt regarding the Permian age of T. solenites was formulated in 2013, evidence for Bolsovian Age (Westphalian C) is suggested, mainly based on the fact that the fossil was found entombed in the Schweddey Ignimbrite, a pyroclastic flow deposit in the Flöha-Falkenau-Basin. Petrography, radiometric dating (310 ± 2 Ma), zircon analysis and details of the geological setting unequivocally show that the majority of this palaeorhyolite, hitherto assigned to as Zeisigwald Tuff in the basin of Flöha-Falkenau, is actually the Schweddey Ignimbrite and thus of Middle Pennsylvanian age. As a consequence, the age of all petrified wood from the Flöha region including that of the Schußberg site (Oederan Forest) needs to be revised.