A phenomenal fossil fern – forgotten for 40 years

On some occasions, it is the hard sweat and toil of palaeontologists labouring in the field at carefully planned excavation sites that yields the prize specimen on which careers are built. On other occasions, it is the chance discovery by an amateur collector that may yield that special fossil. We present an account of one such remarkable fossil discovery by an eccentric farmer in southern Sweden. However, more remarkable is that this exceptional fossil remained unstudied and largely unnoticed in a major museum for almost 40 years, before its true significance was realised.

The story begins near Lake Korsaröd, in the heart of the southern Swedish province of Scania. Gustav Andersson (born 16 May 1915; Fig. 1) owned a small homestead bordering the shores of this lake. Although Gustav made a living from farming, his true passion was natural history and he even adorned the walls of his house with his own sketches of Mesozoic scenes. Although he never received any formal scientific training, Gustav was an avid reader and had a keen eye for nature. He used these skills to identify a great range of plants on his property down to the rare ground orchids that episodically bloomed on the local volcanic soils. He also identified Neolithic burial sites, flints, stone clubs and other ancient human artefacts that lay scattered about the landscape. However, his particular interest was geology. Gustav identified several Jurassic volcanic plugs and Quaternary glacial moraines in the Korsaröd district that had not been recognised by the professional geologists of his day. He was a keen observer of the subtleties of the landscape, which had been shaped by volcanism, rivers and the great Quaternary ice sheets that had covered Scandinavia. He often wrote to the geology professors at Lund University to announce his ideas. Often dismissive of his claims, the academic geologists sometimes had to eat their words, when Gustav patiently took them into the field to show them his discoveries.

Fig. 01. Gustav Andersson from Nils Nilsson
Fig. 1. Gustav Andersson (right) at the site of the fossil wood discovery (taken some time in the 1970s). (Image: Nils Nlisson.)

Perhaps Gustav’s most important discovery came in the late 1960s or early 1970s. On that occasion, he identified a volcanic ash bed, containing a fossil log near the shores of Lake Korsaröd (Fig. 2). At that time, some geologists argued that the volcanic rocks of central Scania were of Cenozoic age, but Gustav argued that his discovery of an entombed petrified log pushed the age of volcanism back to the Mesozoic. He sent off a letter to Lund University to report his discovery. The Lund geologists, ever wary of his theories but nonetheless acknowledging his keen observational skills, dispatched two young men to excavate the site in search of more fossil wood. Unfortunately, Gustav was away at the time, but the two young men laboured for a day and found nothing of value. Some days later, a letter arrived from Professor Helmquist in Lund stating that the site contained nothing of interest for geologists.

Fig. 02. Korsaröd wood
Fig. 2. Fragmentary fossil wood chaotically embedded in a Jurassic volcanic mudflow (lahar) deposit; Korsaröd, Sweden.

Gustav was not impressed. Taking his pick and shovel, he dug deeper into the trench and soon found several pieces of wood up to 7kg in weight. These samples (Fig. 3) he sent to Hans Tralau, who was then an assistant curator at the Swedish Museum of Natural History in Stockholm. Tralau studied the fossil spores and pollen entombed in the ash deposit that contained the wood and confirmed that the beds were indeed of Early Jurassic age.

Fig. 03. Korsaröd wood in collections
Fig. 3. Some of the fossil wood specimens donated to the Swedish Museum of Natural History by Gustav Andersson.

Among the many samples of volcanic rock and fossil wood that Gustav Andersson sent to Hans Tralau was a single peculiar petrified fern rhizome (Fig. 4). Tralau clearly recognised the significance of this fossil because he prepared several thin sections and took a series of photographs of the specimen (Fig. 5). Undoubtedly, Tralau intended to publish a formal description of this fossil, but his untimely death in March 1977 meant that the project was never completed. Archival correspondence at the Swedish Museum of Natural History reveals that, some years later, Britta Lundblad, then head of the Palaeobotany Department, exchanged letters with Gustav Anderssson, also indicating her intention of writing a report on the material. However, her retirement in 1986 left the task unfinished. After that, the fossil lay in the collections and largely went unnoticed by the curatorial staff or the large number of visiting researchers.

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