The Rhynie chert fossils represent one of the most important palaeontological discoveries ever made. This unique Scottish site preserves an Early Devonian ecosystem in astonishing detail. As a result, scientists can learn about an ancient palaeoenvironment.  The biota that existed in a swamp close to hot, mineral-rich springs was like nothing known on Earth today.

Moreover, the Rhynie chert captures life in situ. It preserves hot spring environments, early land plants, arthropods, and microbial communities. Therefore, it provides a rare snapshot of terrestrial ecosystems around 407 million years ago.  As part of a media release concerning a new study into the giant, enigmatic taxon Prototaxites, we received an artist’s impression of the Rhynie chert Devonian landscape.

Artist’s impression of what the environment at Rhynie, Aberdeenshire, where the Prototaxites fossils were discovered, would have looked like 410 million years ago. Picture credit: Matt Humpage.

Picture credit: Matt Humpage

Researching Rhynie Chert Fossils

Recent research has provided additional insight. A recent study suggests that Prototaxites does not belong to fungi or plants. Instead, it may represent an entirely unknown complex life form. This discovery reshapes how we understand early terrestrial life and evolutionary experimentation.

To read our blog post about this research: Beautiful Rhynie Chert Fossils Reveal Their Secrets.

The Rhynie chert fossils continue to challenge long-held assumptions. They demonstrate that Early Devonian ecosystems were already diverse and surprisingly sophisticated. Consequently, this site remains a global reference point for palaeobiology and evolutionary research.

Mike from Everything Dinosaur commented:

“Museum fossil collections are invaluable. Fossils collected decades ago can play a role in new research. Improved analytical techniques allow scientists to re-examine old specimens and uncover fresh insights. We still have so much to learn about our incredible planet and its deep evolutionary history.”

The Rhynie chert fossils continue to transform our understanding of early terrestrial life. They remind us that evolution experimented in unexpected ways during the Devonian.

Everything Dinosaur acknowledges the assistance of the National Museums of Scotland in the compilation of this article.

Visit the Everything Dinosaur website: Models of Prehistoric Animals and Plants.

Newly published research suggests that Early Devonian Prototaxites was a “new” form of life.  This giant organism, represented in the fossil record by columnar fossils up to eight metres tall, is distinct from plants and fungi.  Writing in the academic journal “Science Advances”, scientists from the University of Edinburgh and National Museums Scotland postulate that Prototaxites fossils represent a complex lifeform that is neither a fungus or a plant. Furthermore, the researchers postulate that these novel organisms died out around 360 million years ago.

An artist impression of what Prototaxites would have look like in life. It is surrounded by primitive plants in the Rhynie chert landscape. Picture credit Matt Humpage.

Picture credit: Matt Humpage

Studying Prototaxites Fossils

The fossil at the centre of this investigation comes from the famous Rhynie chert. Named after the nearby village of Rhynie in Aberdeenshire (Scotland), the rocks preserve a terrestrial ecosystem that existed approximately 407 million years ago.  Hot springs saturated with minerals periodically inundated a nearby marsh ecosystem.  The primitive plants and other organisms were preserved in amazingly detail.  Cell walls and pore spaces were replaced by these minerals.  The fossils from this locality provide a unique insight into early terrestrial plant communities.

The fossil material used in this study will be housed and cared for at the National Museums Collection Centre in the north of Edinburgh.

Lead co-author Dr Sandy Hetherington, Research Associate at National Museums Scotland and Senior Lecturer from the School of Biological Sciences at the University of Edinburgh, explained:

“It’s really exciting to make a major step forward in the debate over Prototaxites, which has been going on for around 165 years. They are life, but not as we now know it, displaying anatomical and chemical characteristics distinct from fungal or plant life, and therefore belonging to an entirely extinct evolutionary branch of life. Even from a site as loaded with palaeontological significance as Rhynie, these are remarkable specimens and it’s great to add them to the National Collection in the wake of this exciting research.”

National Museums Scotland Research Associate Sandy Hetherington with a sample of the 410-million-year-old fossil of Prototaxites. Picture credit: Neil Hanna.

Picture credit: Neil Hanna

Prototaxites (P. taiti) Chemically and Structurally Distinct from Fungi

Following an analysis of the Prototaxites fossil material, the research team concluded that this organism was chemically distinct from contemporaneous fungi. In addition, the study demonstrates that it is structurally distinct from all known fungi.

Co-lead and first author Dr Corentin Loron (UK Centre for Astrobiology at the University of Edinburgh) said:

“The Rhynie chert is incredible. It is one of the world’s oldest fossilised terrestrial ecosystems and because of the quality of preservation and the diversity of its organisms, we can pioneer novel approaches such as machine learning on fossil molecular data. There is a lot of other material from the Rhynie chert already in museum collections for comparative studies, which can add important context to scientific results.”

Co-author of the study Corentin Loron from the University of Edinburgh with a slice sample of the Prototaxites fossil. Picture credit: Neil Hanna.

Picture credit: Neil Hanna

A Separate and Entirely Extinct Form of Life

This study casts doubt upon the fungal affinity of Prototaxites, instead suggesting that this enigmatic organism is best assigned to an entirely extinct eukaryotic lineage.

Co-first author Laura Cooper, a PhD student from the Institute of Molecular Plant Sciences at the University of Edinburgh, added:

“Our study, combining analysing the chemistry and anatomy of this fossil, demonstrates that Prototaxites cannot be placed within the fungal group. As previous researchers have excluded Prototaxites from other groups of large complex life, we concluded that Prototaxites belonged to a separate and now entirely extinct lineage of complex life. Prototaxites therefore represents an independent experiment that life made in building large, complex organisms, which we can only know about through exceptionally preserved fossils.”

Dr Nick Fraser, Keeper of Natural Sciences at National Museums Scotland said:

“We’re delighted to add these new specimens to our ever-growing natural science collections which document Scotland’s extraordinary place in the story of our natural world over billions of years to the present day. This study shows the value of museum collections in cutting-edge research as specimens collected over time are, cared for and made available for study for direct comparison or through the use of new technologies.”

Everything Dinosaur acknowledges the assistance of the National Museums of Scotland in the compilation of this article.

The scientific paper: “Prototaxites fossils are structurally and chemically distinct from extinct and extant Fungi” by Corentin C. Loron, Laura M. Cooper, Sean McMahon, Seán F. Jordan, Andrei V. Gromov, Matthew Humpage, Niall Rodgers, Laetitia Pichevin, Hendrik Vondracek, Ruaridh Alexander, Edwin Rodriguez Dzul, Alexander T. Brasier, Michael Krings, and Alexander J. Hetherington published in Science Advances.

The award-winning Everything Dinosaur website: Prehistoric Animal and Prehistoric Plant Models.

Researchers have reported the discovery of a fragment of pterosaur finger bone from the UNESCO World Heritage site Stevns Klint. The Stevns Klint cliffs are located on the eastern coast of the Danish island of Sjaelland. The fossil along with other fragmentary bones, was found in the uppermost Maastrichtian, Højerup Member of the Møns Klint Formation strata of Holtug limestone quarry.  This is the first time that pterosaur remains have been reported from this location.  The specimen is a piece of the phalanx 1 of digit IV (the wing finger).  Its size suggests that small-bodied pterosaurs with a wingspan of less than half a metre existed during the last fifty to sixty thousand years of the Cretaceous.

Unfortunately, it is not possible to determine whether the specimen is an adult or juvenile.  However, if the fossil represents a bone from an adult pterosaur, then this is the smallest pterosaur known from the Late Cretaceous.

It overlaps in size with contemporaneous birds, rejecting previous hypotheses that Late Cretaceous pterosaurs and birds avoided competition through size-based niche partitioning.

Fragments of the pterosaur finger bone and skeletal reconstruction showing location of a bone fragment. Drawing of pterosaur skeleton showing location of fragment OESM 13096 in red (A). OESM 13096 (B) left phalanx 1 of digit IV in ventral view, dorsal (C), posterior (D), proximal (E), and distal (F) views. OESM 13323, fragment of phalanx 2 or phalanx 3 of digit IV in lateral (G) and ventral (H) views, end cross-sections (I, J). Specimen number OESM 13324 (D) unidentifiable fragment displaying numerous (pneumatic) foramina, rotated around vertical axis in different views (K, L, M). Picture credit: Milàn et al.

Picture credit: Milàn et al

Studying a Fragmentary Pterosaur Finger Bone

The preserved fragments indicate the individual was perhaps a tenth to a fifth the size of the smallest of the latest Maastrichtian pterosaurs from Morocco (Alcione elainus). It is not possible to provide a more precise taxonomic assessment of the specimen, other than referring it to the Pterosauria.  The researchers conclude that these bones could indicate a flying reptile with a wingspan of perhaps twenty to fifty centimetres. For comparison, the common blackbird (Turdus merula) has a wingspan of around thirty-five to forty centimetres.  This could be evidence of small pterosaurs present in the late Maastrichtian of the Cretaceous.  Ironically, a time when it had been thought that birds had replaced small pterosaur species.

Everything Dinosaur’s blog post about pterosaur diversity in the Late Cretaceous: Late Cretaceous Pterosaurs More Diverse Than Previously Thought.

The Stevns Klint Palaeoenvironment

The strata comprising the cliffs on the island of Sjaelland are remarkable. The limestone and chalk deposits represent a sequence of deposition from the very end of the Cretaceous through to the Palaeogene (Danian faunal stage of the Palaeocene). As such, these rocks provide scientists with an insight into the last few thousand years of the Cretaceous and the period immediately after the End-Cretaceous extinction event.

It had been thought that the emergence of birds led to the extinction of small pterosaur species. The niches previously occupied by small-bodied pterosaurs were gradually filled by birds. However, this pterosaur finger bone discovery and the other specimens suggest that this might be an oversimplification of the true picture. That small pterosaurs did persist until the end of the Cretaceous.

Palaeogeographic map of northern Europe during the end Maastrichtian, showing the location of the present day Stevns Klint. The nearest coastline was at that time located approximately 150 km northeast in the Fenno-Scandian landmass in what is today southern Sweden. Picture credit: Milàn et al.

Picture credit: Milàn et al

An Additional Implication for the Pterosauria

If the new pterosaur specimen derives from a near or fully grown adult individual, then it is evidence for the presence of at least one taxon of small-bodied pterosaur persisting until the end of the Cretaceous. Intriguingly, this discovery opens up another scenario concerning Late Cretaceous pterosaurs.  If the fossil is from a hatchling or juvenile of a species that attained much larger size when fully grown, then it was already capable of flying great distances.  The fossil material comes from the Højerup Member.  These rocks were laid down in a relatively deep-water environment at least ninety miles (one hundred and fifty kilometres) offshore.  Hatchling pterosaurs were likely super-precocial and capable fliers.

Previous studies suggested that hatchling or juvenile pterosaurs were initially adapted to active sustained flight in restricted, vegetation-filled environments. As they grew and matured, they became more efficient long-distance gliders necessarily utilising more open environments. In turn, this supports the idea of niche partitioning in pterosaurs, where individuals at different ages occupied different ecological niches and environments.  However, this fossil material, if not from an adult, indicates that even young pterosaurs were capable of flying considerable distances in open environments.

The Pterosauria are an enigmatic clade.  They were the first vertebrates to evolve powered flight.   This study highlights that we still have a lot to learn about these remarkable flying reptiles.

Everything Dinosaur acknowledges the assistance of one of the paper’s authors (Jesper Milàn) in the compilation of this article.

The scientific paper: “A diminutive pterosaur from the uppermost Maastrichtian chalk of Denmark” by Jesper Milàn, Sten Lennart Jakobsen and Bent Erik Kramer Lindow published in
Acta Palaeontologica Polonica.

For pterosaur models and figures: Pterosaur and Dinosaur Models.