Dinoflagellates are among the most important organisms in the ocean, forming a major part of the plankton and, in the case of heterotrophic species such as those in the genus Protoperidinium, feeding voraciously on other planktonic cells. Like many protists, they alternate between a swimming, armoured motile stage and a dormant cyst stage that sinks to the seafloor and can survive in sediments for years before germinating. Because the cysts are made of highly resistant organic material, many of them fossilise, leaving a continuous record stretching back hundreds of millions of years. This dual life cycle has forced scientists to maintain two parallel naming systems, one for the living cell and one for the cyst, a convention sanctioned by the International Code of Nomenclature for algae, fungi, and plants. The trouble is that linking a particular cyst to the motile cell that produced it is fiendishly difficult, and misassignments have cascaded through the literature for decades.

The heart of the controversy lay with two cyst-based genera, Selenopemphix and Multispinula. Selenopemphix was erected in 1972 on the basis of an Oligocene specimen of Selenopemphix nephroides from Germany, characterised by thin brown walls, a kidney-shaped outline when viewed from the pole, a deeply incised groove called the parasulcus, and a flattened body with two rounded antapical protrusions. Multispinula, described in 1975 from recent sediments of the Persian Gulf with its type species Multispinula quanta, comprised similar-looking cysts but with distinctive rows of solid spines. Over the years, successive authors shuffled Multispinula into Selenopemphix as a junior synonym, then argued it back out, then merged it again, largely because the position of the archeopyle, the opening through which the motile cell escapes the cyst, could not be reliably determined in all specimens. Whether that opening sat symmetrically on the mid-dorsal line or was offset to one side became the pivotal, and bitterly contested, diagnostic character.

David and her colleagues attacked the problem with an unusually comprehensive toolkit. They collected surface sediments from the Atlantic and Pacific Oceans, concentrated the living cysts using density separation with sodium polytungstate, and then performed the most direct experiment imaginable: they picked out individual cysts under an inverted microscope, placed each one in a microwell with culture medium, and waited for them to germinate at 16 degrees Celsius under a controlled light cycle. Thirty-nine cysts hatched into motile cells, allowing the researchers to observe, for the first time with modern methods, exactly which swimming species emerges from which cyst type. The germinated cells were then stained with a fluorescent dye to reveal the intricate geometry of their cellulose plates, photographed under light microscopy, and examined in exquisite detail with a field-emission scanning electron microscope at the marine biology station in Concarneau.

The results were revelatory. Cysts of Selenopemphix nephroides from the Irish Sea hatched into cells matching Protoperidinium subinerme, confirming a link long suspected but never verified with molecular data. Cysts of Multispinula quanta produced cells resembling Protoperidinium conicum. Most excitingly, twenty-nine cells that emerged from a third, smaller cyst type proved to belong to an entirely unknown species, which the team named Protoperidinium parvivariplatum, a nod to its small size and its remarkably variable second anterior intercalary plate. Its cyst counterpart received the name Multispinula varispinosa, honouring the striking variability in spine length, with some specimens bearing long spines of 5 to 14 micrometres, others short spines of 2 to 4 micrometres, and still others a mixture of both. A fourth cyst, large and strongly compressed, with solid spines and fused bases, was recovered from Lake Saroma in Hokkaido and christened Multispinula robusta, its motile equivalent being the classic Protoperidinium conicum described from Norwegian waters.

To place these organisms on the tree of life, the team extracted and sequenced partial large-subunit ribosomal DNA from single germinated cells and from individual cysts, generating twelve new sequences. Bayesian and maximum-likelihood phylogenetic analyses produced a clear and consequential picture: the type species of the two contested genera sit in entirely different branches of the Protoperidinium sensu stricto clade. Selenopemphix nephroides and its relatives cluster within the section Tabulata, while Multispinula varispinosa, together with previously published sequences of Protoperidinium conicum and Protoperidinium cf. conicum, belongs to the section Conica. The two cyst-based genera are therefore polyphyletic if lumped together, meaning that treating them as one genus would group organisms that are not each other’s closest relatives. The sequence divergence was substantial, with Protoperidinium parvivariplatum showing only 85 to 89 percent similarity to its supposed congener Protoperidinium conicum, and the new species formed a well-supported clade with 100 percent bootstrap support.

Morphology told the same story from a different angle. Scanning electron microscopy confirmed that the archeopyle of Selenopemphix nephroides is genuinely offset from the mid-dorsal line, while that of Multispinula varispinosa sits squarely in the centre. Even more strikingly, the electron micrographs revealed, for the first time, a paratabulation on Multispinula cysts, a ghostly map of the plates of the ancestral motile cell traced by rows of spines connected by parasutural ridges across the precingular and postcingular zones. Selenopemphix, by contrast, restricts its ornamentation to the raised margins of the paracingulum. Armed with this convergence of molecular and morphological evidence, the authors formally emended both genera: Selenopemphix now includes only cysts with an offset archeopyle and ornamentation confined to the paracingular margins, while Multispinula is re-established for cysts with a mid-dorsal archeopyle and paratabulation outlined by spines and ridges. Multispinula quanta was transferred back to its original name, and the genus now comprises three species, each tied to a different motile cell and each occupying a distinct thermal niche, from the cold-water Multispinula robusta of Hokkaido and the North Sea to the warm-temperate Multispinula quanta of the Persian Gulf, the Yellow Sea, and the Bay of Biscay, with the broadly tolerant Multispinula varispinosa spanning cold to temperate waters in between.

Perhaps the most forward-looking part of the study went beyond shape and sequence altogether. Using attenuated total reflection Fourier transform infrared microspectroscopy, or ATR µ-FTIR, the team analysed the biomacromolecular composition of individual cyst walls, collecting eighteen spectra from modern and fossil specimens, including six fossil Selenopemphix nephroides dating back to the Rupelian stage of the Oligocene. The spectra revealed that both genera build their walls from a mixture of proteins and melanin-like pigments, the aromatic rings of the latter being responsible for the characteristic brown colouration. But the proportions differ fundamentally: Multispinula cysts are relatively enriched in proteins and poorer in melanin compared with Selenopemphix. This chemical distinction is not merely a curiosity. Proteins are labile molecules that microbes typically hydrolyse within roughly one hundred thousand years of burial, whereas melanin is extraordinarily resistant, having been documented in deposits as old as the Carboniferous. Fossil Selenopemphix nephroides specimens showed exactly the expected maturation signature, retaining their aromatic pigment bands while progressively losing carbohydrate features, a pattern mirroring the thermal evolution of sporopollenin in plant spores.

The implications ripple outward through the fossil record. Multispinula cysts first appear, tentatively, in the upper Oligocene around 23 million years ago, and Multispinula varispinosa is confirmed only from the Pleistocene onward, whereas Selenopemphix nephroides reaches back to the lower Eocene, more than 47 million years before the present. The authors argue that the protein-rich, less melanised walls of Multispinula impose a genuine stratigraphic preservation limit, biasing the apparent evolutionary history of the group and shortening its fossil record relative to its more chemically robust relatives. They caution that palaeoenvironmental studies relying on poorly fossilisable cyst taxa should interpret stratigraphic occurrences with care, and they note that cysts germinated in the laboratory carry chemical contaminants, from lipids and nucleic acids to extracellular polymeric substances, that naturally germinated specimens shed in the sediment, likely through the activity of microbial communities that metabolise labile components while leaving the resistant dinosporin layers intact.

In an era when biodiversity is being inventoried at every scale, from whales to microbes, this study is a reminder that even the tiniest organisms can hold big surprises, and that resolving their identities requires patience, ingenuity, and a willingness to grow them in a dish. By hatching cysts one by one, sequencing their genes, imaging their architecture at nanometre scales, and reading their molecular fingerprints with infrared light, David and her colleagues have not only settled a fifty-year argument but also demonstrated a template for future taxonomy: morphology, molecules, and chemistry, integrated, can reveal hidden species, correct old mistakes, and even explain why some creatures vanish from the rock record while others endure. For the humble dinoflagellate cyst, a grain of organic matter smaller than a speck of dust, the fossil record will never look quite the same again.

Subject of Research: Taxonomic revision of the dinoflagellate cyst genera Selenopemphix and Multispinula using morphology, molecular phylogenetics, and cyst wall chemistry

Article Title: Emendation of the genera Selenopemphix and Multispinula (Peridiniales, Dinophyceae), with the description of Multispinula varispinosa sp. nov. and Multispinula robusta sp. nov.

Article References: David, O., Meyvisch, P., Gu, H., Bilien, G., Clarke, D., Marret, F., & Mertens, K. N. (2026). Emendation of the genera Selenopemphix and Multispinula (Peridiniales, Dinophyceae), with the description of Multispinula varispinosa sp. nov. and Multispinula robusta sp. nov.. Journal of Micropalaeontology, 45(2), 547-576. https://doi.org/10.5194/jm-45-547-2026

Image Credits: AI Generated

DOI: 10.5194/jm-45-547-2026

Keywords: dinoflagellate cysts, Selenopemphix, Multispinula, Protoperidinium, taxonomy, LSU rDNA phylogeny, ATR FTIR spectroscopy, cyst wall composition, micropalaeontology, new species, fossil preservation, marine plankton

The new species, whose name translates to Jean’s crawler from Mazon Creek, is described in the Journal of Vertebrate Paleontology. Jeanerpeton mazonensis belongs to a group of early tetrapods that sit close to the ancestry of modern amphibians. To picture the animal, imagine a salamander in general body plan, but compressed and rotund, more like a frog in proportions. It was a small predator of the coal swamps, part of the sprawling evolutionary experiment in terrestrial and semi-aquatic life that followed the first vertebrates onto land. Its formal description, authored by co-lead scientists Payton Kohlberg and Allison Sefcovic along with postdoctoral researcher Cam So, formally establishes the animal as anatomically distinct from the species to which it had long been assigned.

The exceptional quality of the specimen owes everything to the geology of Mazon Creek. During the Carboniferous, the delta environment buried dead animals and plants rapidly under layers of fine sediment, a perfect recipe for fossilization. Rapid burial in anoxic conditions limited scavenging and decay, allowing delicate structures to survive the hundreds of millions of years between death and discovery. Today, Mazon Creek is recognized as one of the world’s premier fossil sites, a Konservat-Lagerstätte of the kind that preserves records of soft tissues and fine anatomical details normally lost to the fossil record. Where most fossil sites yield bones and shells alone, Mazon Creek can preserve body outlines, skin surfaces, and internal soft anatomy, giving scientists an unusually complete window into a 300-million-year-old ecosystem.

That preservation is precisely what makes the new species so scientifically valuable. What’s really cool about Mazon Creek is that it preserves all of these unusual details, things like toe pads and body outlines, says Allison Sefcovic, co-lead author of the paper and a 2025 Women in Science intern at the Field Museum. In the fossil of Jeanerpeton, researchers can see some of the scales on its back and tiny belly ribs called gastralia. Even the impressions of the eyes are visible. These features, preserved in remarkable fidelity, point to a deep origin for classic traits seen in today’s frogs and salamanders, anchoring the anatomy of modern amphibian lineages to a specific moment in the late Carboniferous.

The story of the fossil itself is a familiar one in paleontology. The specimen was found many years ago by an amateur collector and donated to the Field Museum, where at a glance it was classified as Amphibamus grandiceps, a species with a well-established presence in the region. For decades, the fossil sat in the collection under that label, its true distinctiveness masked by an old taxonomic habit. In paleontology, poorly understood specimens are sometimes lumped together into what scientists call a waste bin taxon, a metaphorical dumping ground for fossils that seem related but have not been carefully studied. Such taxa are convenient shorthand, but they can hide genuine diversity, quietly absorbing distinct species into a single catch-all name until someone takes a closer look.

That closer look is exactly what the new study provides. What we’re finding from the Field Museum’s collection are a bunch of things that historically were grouped together into this waste bin taxon known as Amphibamus grandiceps, says Cam So, co-author on the study and a postdoctoral researcher at the Field Museum. Jeanerpeton is one of those species. And now, we’ve found enough evidence to support it being an anatomically distinct animal. With this publication, we officially pull Jeanerpeton out of this waste bin taxon. The formal designation of a new genus and species is more than a naming exercise; it is a correction to the fossil record’s accounting, restoring a lineage that had been hiding in plain sight within museum drawers.

The research also carries a human story that has resonated widely. The study’s co-lead authors, Payton Kohlberg and Allison Sefcovic, were part of last year’s cohort of Women in Science Interns at the Field Museum, a program that champions young women pursuing careers in science and museums. Both worked under the mentorship of Arjan Mann, the Field’s assistant curator of fossil fishes and early tetrapods in the Negaunee Integrative Research Center, alongside So, who is also part of the Mann lab group. That a new species was described, named, and published by student scientists early in their careers is a testament to the model of hands-on research training, in which interns take genuine ownership of scientific questions rather than serving only as assistants.

For Kohlberg, the project was transformative as much as it was scientific. Before working in the Mann Lab, I didn’t know much about paleontology, she says. My experience at the Field and in the Women in Science program has made me more confident in my abilities to try something new. It is scary to take on a project when you feel like you don’t know as much as you should, but I learned with my practical experience that it is possible to overcome that fear with hard work. The choice of the name Jeanerpeton, honoring two mothers named Jean, reflects the personal significance of that journey, and it gives the ancient animal a warm and memorable identity in the scientific literature.

Scientifically, the description of Jeanerpeton mazonensis opens a door for researchers as they continue to chronicle the biodiversity that once lived at Mazon Creek. Amphibamiforms, the group to which the new species belongs, are central to debates about the origins of modern amphibians, the lissamphibians comprising frogs, salamanders, and caecilians. Every anatomically distinct species added to the group refines the character data that phylogenetic analyses use to reconstruct those relationships. The exceptionally preserved features of Jeanerpeton, from its dorsal scales to its gastralia to its eye impressions, supply exactly the kind of fine-grained anatomical evidence that such analyses require, and its removal from the Amphibamus grandiceps waste bin taxon cleans up a source of noise in previous comparisons.

Each new species described from Mazon Creek adds another piece to a detailed mosaic of what life looked like in Illinois more than 300 million years ago, a time when the foundations of modern terrestrial ecosystems were being laid. The Carboniferous world of Jeanerpeton was one of rising forests, oxygen-rich air, and evolutionary experimentation among the first four-limbed vertebrates to make a living on land and in fresh water. That a pair of student interns could pull a new animal out of a century-old museum collection and give it a name rooted in family gratitude is a reminder that paleontology’s greatest discoveries are often not made in remote badlands, but in the careful re-examination of fossils already in our care, waiting for the right eyes.

Subject of Research: A new exceptionally preserved Carboniferous proto-amphibian species from Mazon Creek and its taxonomic reclassification

Article Title: Mother of amphibians: New species of proto-amphibian described by two student scientists, named in honor of their moms

Article References: Mother of amphibians: New species of proto-amphibian described by two student scientists, named in honor of their moms. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: Jeanerpeton mazonensis, Mazon Creek, Carboniferous, paleontology, amphibians, Field Museum, tetrapods, fossil preservation, waste bin taxon, Women in Science, Amphibamus grandiceps, early tetrapod evolution

SVP asserts that fossils of such profound scientific importance belong in accredited public institutions like museums and universities. These institutions provide the rigorous documentation, preservation, and continual accessibility essential for ongoing research and public education. Without such stewardship, the scientific potential of these irreplaceable records of Earth’s biological past risks being irreversibly compromised.

Vertebrate fossils preserve unique insights into ancient life, encompassing evolutionary patterns, paleobiology, and paleoecology. Yet, the true value of these specimens often unfolds long after their discovery. Kristina Curry Rogers, SVP Vice President, underscores that the initial fossil find is only a prelude to decades of scientific inquiry enabled by emerging technologies and methodologies.

Cutting-edge research tools such as high-resolution computed tomography (CT) scans reveal intricate internal structures, while geochemical and molecular analyses unlock data on growth processes, disease, and environmental interactions of extinct organisms. These techniques thrive on access to well-preserved fossils housed in public collections, where they can be revisited as scientific questions and technologies evolve.

The role of private collectors, landowners, and commercial excavators in unearthing remarkable fossils is acknowledged and valued. Nonetheless, SVP emphasizes that safeguarding a specimen’s long-term scientific significance requires meticulous record-keeping, professional curation, and public accessibility—standards sometimes unmet in private sales and auctions.

As the market for dinosaur fossils escalates, public institutions face increasing obstacles in acquiring key specimens for research and education. The transfer of critical fossils into private hands, absent provisions for scientific access, threatens to stifle future discoveries and diminish the educational potential of these finds.

SVP calls for collaborative frameworks involving fossil discoverers, auction houses, and potential buyers to prioritize the preservation of scientific heritage. Ensuring that important vertebrate fossils remain accessible in public repositories is paramount for advancing paleontological knowledge and sharing humanity’s ancient biological legacy.

Founded in 1940, the Society of Vertebrate Paleontology remains dedicated to the ethical stewardship and study of fossil vertebrates, fostering scientific progress through research, education, and conservation.

Subject of Research: Tyrannosaurus rex fossil preservation and scientific accessibility
Article Title: The Scientific Stakes Behind the Auction of “Gus,” a Nearly Complete Tyrannosaurus rex
News Publication Date: Not provided
Web References: Not provided
References: Not provided
Image Credits: Not provided

Keywords: Tyrannosaurus rex, vertebrate paleontology, fossil preservation, scientific curation, public research institutions, CT imaging, geochemical analysis, molecular paleontology, fossil auction, Society of Vertebrate Paleontology