Carla J. Harper

Trinity College Dublin | TCD · Department of Botany

Premise of the Research The fossil record shows that seed plants appeared during the Devonian and started to become dominant in the Mississippian. However, the identity of their closest relatives remains uncertain with three candidates: Stenokoleales, Archeopteridalean progymnosperms, and Aneurophytalean progymnosperms. To clarify the relationship...

The various types of spherical microfossils collectively termed fossil fungal “sporocarps” exhibit basic congruities in morphology that have been used to suggest they all may belong to the same higher taxonomic category. Both the Ascomycota and zygomycete fungi have been discussed in this respect, but features that precisely delimit the nature and...

The Jurassic vegetation of Antarctica remains poorly known and, while there have been several reports of large fossil trees from that time period across the continent, detailed anatomical studies of their wood are extremely scarce. Here we describe new silicified woods of Early Jurassic (probably Toarcian) age from Carapace Nunatak, South Victoria...

Tyloses are swellings of parenchyma cells into adjacent water-conducting cells that develop in vascular plants as part of heartwood formation or specifically in response to embolism and pathogen infection. Here we document tyloses in Late Devonian (approximately 360 Myr ago) Callixylon wood. This discovery suggests that some of the earliest woody t...

Tyloses are protoplasmic swellings of parenchyma cells into the lumen of adjacent conducting cells. They develop as part of the heartwood formation process, or in response to embolism or pathogen infection. Here, we report the oldest fossil evidence to date of tylosis formation that occurs in permineralized wood of the (pro)gymnosperm Dameria hueb...

Our understanding of vegetation changes around the Devonian-Carboniferous boundary remains limited by the small number of plant-yielding deposits close in age to the boundary. In this context, we have started to reinvestigate Devonian-Carboniferous localities of Ireland, with an initial focus on those from which Matten and collaborators (1980, 1983...

Fungal parasites are important drivers in ecosystem dynamics today that can have far-reaching effects on the performance and community structure of other organisms. Knowledge of the fossil record and evolution of fungal parasitism is therefore a key component of our understanding of the complexity and functioning of ancient ecosystems. However, the...

Premise of research. As our understanding of the importance of fungi in ecosystems today increases, we are still in the early stages of appreciating their roles in the past. The famous Early Devonian Rhynie chert contains a remarkable diversity of fungal fossils and copious evidence of fungal interactions; however, only relatively few of them have...

Glomeromycotan propagules (spores) are morphologically diverse in the Early Devonian Rhynie chert; however, only relatively few of these fossils have been documented and critically evaluated. This study re-examines propagules previously described informally as ‘reproductive unit 1’, and identified as glomeromycotan acaulospores borne within the nec...

The fossil record contains abundant evidence of the hyperdiverse kingdom Fungi. Macrofungi (Ascomycota, Basidiomycota) enter this record in the Paleozoic, some 360–540 myr ago. Common modes of preservation of macrofungi include impression, compression, petrifaction, and permineralization; delicate mushrooms may also occur as amber inclusions. Fossi...

The Lower Devonian Rhynie and Windyfield cherts from Scotland contain a remarkable diversity of microscopic fungal propagules and reproductive units; however, only relatively few of these fossils are described. One of them is Windipila spinifera, an unusual reproductive unit from the Windyfield chert that consists of a walled spheroid (~ 100 µm in...

Glomeromycotan spores from the Early Devonian Rhynie chert frequently contain evidence of colonization by other fungi. However, relatively few of these relationships have been described and evaluated. Brijax amictus gen. et sp. nov., a probable chytrid (Chytridiomycota) associated with certain thick-walled archeosporalean acaulospores from the Rhyn...

Background and aims: Structurally preserved arbuscular mycorrhizas from the Lower Devonian Rhynie chert represent core fossil evidence of the evolutionary history of mycorrhizal systems. Moreover, Rhynie chert fossils of glomeromycotan propagules suggest that this lineage of arbuscular fungi was morphologically diverse by the Early Devonian; howev...

The biology of trees that grew in high‐latitude forests during warmer geological periods is of major interest in understanding past and future ecosystem dynamics. As we study the different plants that composed these forests, it becomes possible to make comparisons with ecosystem processes that occur today. Here we describe a silicified late Permian...

Permineralized peat from the central Transantarctic Mountains of Antarctica has provided a wealth of information on plant and fungal diversity in Middle Triassic high-latitude forest paleoecosystems; however, there are no reports as yet of algae or cyanobacteria. The first record of a fossil filamentous cyanobacterium in this peat consists of wide,...

For 300 years, fossil plants from fluvial deposits of the Manebach Formation (Asselian, central Germany) have kept both collectors and scientists in their spell, and their investigation is considered to represent the onset of palaeobotany. Compressions and casts of various plant organs, many of them preserved in striking detail, provided insights i...

Perexiflasca tayloriana, a widespread microfossil in the Lower Devonian Rhynie chert from Scotland, consists of a thin-walled cavity surrounded by a prominent sheath. A single tube extends from the cavity to the surface. Specimens occur singly or aggregated in decaying plant tissue and on fungi. Perexiflasca tayloriana has been attributed to the Ch...

Premise of research. Microbial mats in the Lower Devonian Windyfield chert comprise diverse communities of organisms; however, little information on the various life forms that occur in these formations is available. A recently cut and thin-sectioned block of Windyfield chert contains an extensive microbial mat that formed among an in situ stand of...

Rhyniococcus uniformis from the Lower Devonian Rhynie and Windyfield cherts, Scotland, occurs in the form of unistratose, plate-like colonies comprised of (8–)16–>250 cell units (3–5 μm in diameter) situated in rows more or less perpendicular to one another; quadruplets and 16-cell unit clusters are often recognizable as modular units. The fossil r...

Documented evidence of fungi associated with Mesozoic ferns is exceedingly rare. Three different types of fungal remains occur in a portion of a small, permineralised fern stem of uncertain systematic affinities from the Triassic of Germany. Exquisite preservation of all internal tissues made it possible to map the spatial distribution of the fungi...

Microbial mats in the Lower Devonian Rhynie chert represent diverse communities of organisms, which probably not only co-occurred in these structures, but also variously interacted with one another. However, little is known about these interactions. Three different types of fungi interact with clusters of small propagules that frequently occur with...

In this chapter we propose a model for the early evolution of eukaryotic cells under pressure of intense endoparasitism. Defining features of eukaryotes developed to defend against endoparasites (primarily bacteria), including a defensive system composed of an antioxidant sterol-enriched internal and external membrane system that could be used to e...

Transformative Paleobotany: Papers to Commemorate the Life and Legacy of Thomas N. Taylor features wide-ranging coverage that includes the broadest possible spectrum of topics analyzing the structure, function and evolution of fossil plants, microorganisms, and organismal interrelatedness in fossil ecosystems (e.g., plant paleobiography, paleoecolo...

New specimens of the fungal reproductive unit Windipila spinifera from the Lower Devonian Windyfield chert (Scotland) are better preserved than the original material, and thus now permit a more precise definition and photographic documentation of this peculiar microfossil. A mantle composed of circumferential hyphae and prominent, thin-walled proje...

Presentation/seminar on Endoparasitism-Driven Eukaryogenesis to be given at Lanzhao University, China May 6-20, 2018. Seminar covers most of what is contained in the chapter 'Reactive Oxygen Defense Against Cellular Endoparasites and the Origin of Eukaryotes'.

Article in press: Documented evidence of fungi from the Permian of Antarctica is exceedingly rare and mostly consists of dispersed remains that do not provide the whole complement of diagnostic features necessary to determine systematic affinities A dense cluster of >250 fungal spores occurs within what appears to be a degraded glossopterid reprodu...

Various types of other fungi colonize glomeromycotinan (Mucoromycota) spores in the Early Devonian Rhynie chert. However, relatively few of these associations have been described and evaluated in detail. One particular type of glomoid spore located in degrading land plant axes from the Rhynie chert provides evidence of (simultaneous) interaction wi...

The Lower Devonian Rhynie chert is one of the most important rock deposits yielding comprehensive information on early continental plant, animal and microbial life. Fungi are especially abundant among the microbial remains, and include representatives of all major fungal lineages except Basidiomycota. This paper surveys the evidence assembled to da...

In this chapter we propose a model for the early evolution of eukaryotic cells under pressure of intense endoparasitism. Defining features of eukaryotes developed to defend against endoparasites (primarily bacteria), including a defensive system composed of an antioxidant sterol-enriched internal and external membrane system that could be used to e...

Photoautotrophic microorganisms were likely abundant in the Early Devonian Rhynie ecosystem; however, documented evidence of these life forms is rare. Hagenococcus aggregatus nov. gen. et sp. occurs in the Rhynie chert matrix as solitary cells, dyads, triads, linear, decussate, and isobilateral tetrads, sarcinoid packets, short filaments, irregular...

Six different types of small fungal reproductive units with ancillary coverings in the form of hyphal mantles have been described from the Lower Devonian Rhynie chert in Aberdeenshire, Scotland. This paper presents the first record of a mantled fungal reproductive unit from the closeby, broadly coeval Windyfield chert. Specimens consist of a walled...

Small, detached fungal reproductive units are almost ubiquitous in the Early Devonian Rhynie chert; however, only a few of these fossils have been described. Three morphologically distinctive types of spheroidal reproductive units occur in litter layers from the Rhynie chert. One of these is >250 μm in diameter and has a multi-layered wall; the out...

Unusual microfossils that occur associated with fungal spores in the Lower Devonian (~410 Ma) Windyfield chert from Scotland are comprised of a narrow stipe (2.5–9 μm long) to which is attached an obovoid or elongate drop-shaped cell up to 14 μm long; a basal attachment pad is present in several specimens. The fossils are strikingly similar morphol...

The intraradical portion of arbuscular mycorrhizal (AM) fungi comprises mycelium, vesicles, and special physiological interfaces termed arbuscules; sometimes mycorrhizal fungi also produce spores within their hosts. Arbuscules are ephemeral structures that collapse after a few days, while the hyphae and vesicles appear to remain intact for some tim...

Evidence of fungal decay is frequently encountered in silicified wood. However, studies focusing on fossil fungal wood degradation remain rare. A characteristic pattern of degradation and decay symptoms congruent with present-day white pocket rot occur in Late Permian silicified glossopteridalean stem and root wood (Australoxylon sp.) from Skaar Ri...

Combresomyces cornifer is a conspicuous spheroidal microfossil (<40 μm diam.) that occurs in Mississippian (~330 Ma) chert from France and is characterized by a prominent surface ornament of antler-like extensions positioned on hollow, conical or column-like wall papillations. The fossil has been interpreted as a peronosporomycete oogonium based on...

Among the few Lower Jurassic sites with plant remains known from Antarctica, Carapace Nunatak, in South Victoria Land, is emerging as one of the richest. It contains different types of plant fossils (pollen, silicified plants, compressions/impressions, and fusain), which opens the door to promising multidisciplinary studies on past biodiversity and...

Chert and silicified wood from the Permian through Cretaceous of Antarctica contain abundant information on fungal diversity and plant–fungal interactions. The chert deposits represent a particularly interesting setting for the study of plant–fungal interactions because they preserve remains of distinctive high latitude forest ecosystems with polar...

Zwergimyces vestitus, a fungal reproductive unit enveloped in a mantle of interlaced circumferential hyphae from the Lower Devonian Rhynie chert, was formally described based on limited information obtained from six specimens. In this paper, we provide additional insights into the organization of Z. vestitus, together with specific developmental de...

Fungi today occur on virtually every plant part, living and dead, and represent a significant proportion of fungal diversity. Arborescent seed ferns characterized by large, tongue-shaped leaves with reticulate venation (Glossopteris) represent the dominant floral element in the Permian of Gondwana. However, documented evidence of fungi associated w...

Several specimens of a new fungal reproductive unit, Halifaxia taylorii nov. gen. et spec., occur within the tracheids of a structurally preserved fern axis from the Lower Pennsylvanian of Great Britain. The reproductive units, which appear to be lateral outgrowths of tubular hyphae, consist of a mantled sphere (80–90 mm in diameter) borne termi...

Paleoecological interactions among fossil microorganisms have garnered significant interest within the paleobotanical community; however, an understanding of the early diagenesis of associated plant material is of critical importance when assessing putative body fossils of fungi and bacteria. Structures preserved within permineralized petioles of t...

Spherical to pyriform microfossils containing multiple smooth-walled spherules from the Lower Devonian Rhynie chert are described as oogonia of a new fossil peronosporomycete based on congruencies in basic morphology to the polyoosporous oogonia of certain extant Saprolegniales. Because the new fossils also resemble Frankbaronia polyspora, a putati...

Well-preserved fungi occur in permineralized conifer axes from the Lower Jurassic of northern Victoria Land, Antarctica. The fungus is characterized by septate hyphae extending through the vascular ray system via penetration of cross-field pits. Tyloses are present in large numbers and might have been effective as a physical restraint to the spread...

A conspicuous silicified microfossil, Frankbaronia polyspora n. gen. n. sp., occurs in plant litter and as an inhabitant of microbial mats from the Lower Devonian Rhynie chert, Aberdeenshire, Scotland. Specimens are elongate-cylindrical, oval, or spherical, thin-walled, and may possess conical or column-like surface projections. Most specimens occu...

A conspicuous silicified microfossil, Frankbaronia polyspora n. gen. n. sp., occurs in plant litter and as an inhabitant of microbial mats from the Lower Devonian Rhynie chert, Aberdeenshire, Scotland. Specimens are elongate-cylindrical, oval, or spherical, thin-walled, and may possess conical or column-like surface projections. Most specimens occu...