Cyrille Prestianni | Royal Belgian Institute of Natural Sciences (original) (raw)
Papers by Cyrille Prestianni
Palaeontologia Electronica, 2018
Morphometric characters of fossil leaves such as size and shape are important and widely used sou... more Morphometric characters of fossil leaves such as size and shape are important and widely used sources for reconstructing palaeoenvironments. Various tools, including CLAMP or Leaf Margin Analysis, utilize leaf traits as input parameters for estimating
palaeoclimate, mostly based on correlations between traits and climate parameters of extant plants. During the last few years, the scope of information extracted from the morphology of fossil leaves has been further expanded by including leaf economics, which describe correlations between functional leaf traits and ecological strategies. The amount and quality of available data are essential for a successful palaeoecological analysis utilizing leaf traits. Here, the database MORPHYLL is described. This database is devised to offer a web-based resource for fossil leaf trait data. For this purpose, fossil leaves from various collections were digitized and morphometric traits extracted from leaf outlines. Besides metadata such as accession number, repository, fossil site or taxonomic information (for identified specimens), MORPHYLL offers queries for several morphometric parameters and derived ecophysiological traits (e.g., leaf mass per area). Currently, the database contains data from about 6000 fossil leaves from sites in Central Europe, spanning almost the entire Paleogene and part of the
early Neogene. The application potential of the database is demonstrated by conducting some exemplary analyses of leaf traits for the Paleocene, Eocene and Oligocene, with the results indicating changes of mean leaf traits through time. For example, the results show leaf mass per area to peak during the Eocene, which is in accordance with general climate development during the Paleogene.
The multiovulate cupule of a new spermatophyte, Thorezia vezerensis gen. et sp. nov. , is describ... more The multiovulate cupule of a new spermatophyte,
Thorezia vezerensis
gen.
et
sp. nov.
, is described from the Late Devonian
aged sediments from Trooz Quarry in Belgium. In gross morphology, it conforms to the
Moresnetia
morphotype and has a
cupule that is composed of four independent quarters that each dichotomises three times. Each cupule quarter contains one
single ovoid preovule with a long pedicel and an integument that has small apical teeth surrounding a rudimentary
micropyle. Morphological variability in the materials examined is interpreted as being related to preovule maturity, and from
this a good understanding of the ontogenetic development from preceding dispersal has been developed. Up to now, 17
spermatophyte species have been described, 11 of which come from eastern Laurussia. This diversity in eastern Laurussia
contrasts strongly with the low diversity characterizing contemporaneous floras from other phytogeographical areas. We
suggest here that the arid climatic conditions prevailing in eastern Laurussia favoured the development of diverse
spermatophyte communities and contributed to reduced diversity and abundance of contemporaneous free-sporing plant
diversity.
Well-preserved specimens of Stauropteris oldhamia are described. The material was collected in th... more Well-preserved specimens of Stauropteris oldhamia are described. The material was collected in the early 1920s from the Lower Westphalian (Early Pennsylvanian) Saurue seam from Belgium. The fossil plants occur as permineralized axes fragments within a coal ball. This study confirms most of the interpretations made by previous researchers. The observation of immature axis however suggests a less regular organization than previously interpreted beyond the three first branching orders. We also highlight the presence of profusely and dichotomously branched aphlebiae, the lack of laminate organs as well as the presence of hypodermal aerenchyma in all plant parts. We interpret these features as part of a very specialized assimilatory apparatus indicating an adaptation to a humid swamp environment.
We review progress made during the last 25years in our understanding of the Protopityales, Early ... more We review progress made during the last 25years in our understanding of the Protopityales, Early Carboniferous plants
belonging to the extinct group of the progymnosperms. Recent studies support previous observations that the only genus of
this order,
Protopitys
, included large arborescent plant with trunks up to 1m in diameter. All branch orders had an oval
eustele, secondary xylem with small rays and tracheid pitting ranging from circular bordered to scalariform bordered, and
vascular traces to lateral appendages emitted in an alternate to subopposite distichous arrangement. Leaf morphology
remains unknown. New material also confirms that fertile organs of
Protopitys
consist of branching systems bearing
elongated sporangia terminally. Spores have a perispore and range in two size groups, which has been interpreted as a
primitive stage of heterospory. The dense wood and fertile parts of
Protopitys
are comparable to those of the
aneurophytalean progymnosperms of the Devonian, but
Protopitys
is distinct by its eustelic primary vascular system, and its
affinities are still uncertain. The genus is now documented from at least nine localities in Europe, North America and
Australia. Recent discoveries also indicate that it was present through the whole Mississippian, from the middle Tournaisian
to the Serpukhovian.
Premise of research. Although the most comprehensively known Devonian seeds were borne in a “telo... more Premise of research. Although the most comprehensively known Devonian seeds were borne in a “telomic”
cupule, those of some species have been postulated as being borne terminally on naked axes lacking a cupule.
Uncertainty remains as to whether such seeds were shed from a cupule before preservation. We reinvestigate
the Upper Devonian fossils Pseudosporogonites hallei and Xenotheca bertrandii from Belgium and the similar
ovules Aglosperma quadrapartita and Aglosperma avonensis from Britain and Aglosperma sp. from North
America to consider their structure and organization and to determine whether they were cupulate.
Methodology. Compressions/adpressions of X. bertrandii and Pseudosporogonites from Belgium and A.
quadrapartita and A. avonensis from the United Kingdom, as well as Anglosperma sp. from Pennsylvania,
were prepared, mainly by de´gagement. Observation and photography were carried out using crossed polarizing
filters.
Pivotal results. Pseudosporogonites hallei, X. bertrandii, and A. quadrapartita comprise single ovules
borne within small, radially symmetrical, uniovulate cupules. Integuments are entire at the chalaza but form
flattened lobes distally. While a cupule is unknown in A. avonensis, its comparable integument morphology
suggests that it was shed from a uniovulate cupule. Although the species are distinct from each other, their
similarities show that they are closely related and belong to a single genus, for which the name Pseudosporogonites
has priority. We emend P. hallei in light of our findings and erect the combinations P. bertrandii
(Stockmans) C. Prestianni, J. Hilton et W. Cressler, P. quadrapartitus (J. Hilton et D. Edwards) C. Prestianni,
J. Hilton et W. Cressler, and P. avonensis (J. Hilton) C. Prestianni, J. Hilton et W. Cressler.
Conclusions. The uniovulate cupule in Pseudosporogonites is distinct from multiovulate telomic cupules
of other Devonian seeds and expands the phenotypic diversity seen during the earliest phase of seed plant
radiation, which was geologically instantaneous. Hydrasperman pollination in all proven Devonian seeds
demonstrates evolution from a common ancestor, but finding morphological intermediates between seed and
free-sporing plants remains a significant challenge to evolutionary plant biology.
The Ourthe valley in eastern Belgium provides the most complete exposures of the upper Famennian ... more The Ourthe valley in eastern Belgium provides the most complete exposures of the upper Famennian Condroz Group.
A detailed miospore stratigraphy has been established for this succession. The lower three miospore biozones of the Upper Famennian
(GF, VCo and VH Oppel Zones) are re-defined and subdivided into five new interval zones. The GF Oppel Zone which spans the Middle
and Upper Famennian boundary was previously subdivided into three interval zones is now reduced to two. The highest Retispora
macroreticulata (Mac) Interval Zone is now removed (due to its very sporadic occurrence) which results in the Grandispora microseta
(Mic) Interval Zone of the GF Oppel Zone now being the lowest miospore interval zone of the Upper Famennian. The overlying
VCo Oppel zone is subdivided into two new interval zones, the Rugospora radiata (Rad) and overlying Grandispora cornuta (Cor)
interval Zones. A detailed study based on new and published material of the two nominal zonal taxa of the VCo Zone has clarified their
morphology and resolved identification problems with other closely related Upper Devonian taxa. Furthermore, a biometric comparison
of Grandispora cornuta with Grandispora tamarae has resulted in the specific diagnosis of G. cornuta being emended to increase its
minimal spine length to 8 μm. The biostratigraphic implications for intercontinental correlations with the Upper Famennian of North
America are discussed. The overlying VH Oppel Zone is subdivided into two new interval zones, the Apiculiretusispora verrucosa
(Ver) Interval Zone and the overlying Vallatisporites hystricosus (Hys) Interval Zone. All of the new miospore interval zones are closely
correlated with the well established conodont zones occurring in five sections of the Ourthe Valley. The new integrated data sets provide
a high resolution biostratigraphy for the Upper Famennian stratigraphic interval in eastern Belgium.
The rhizomorphs of Early (Devonian and Early Carboniferous) arborescent lycopsids are known from ... more The rhizomorphs of Early (Devonian and Early Carboniferous) arborescent lycopsids are known from only a handful of taxa. That of Leptophloeum is previously described from a single fragmentary specimen from China that, in our opinion, has been incorrectly interpreted. Here we describe several relatively well-preserved examples of Leptophloeum rhizomorphs from the Famennian aged Waterloo Farm Lägerstatte of South Africa. We demonstrate an unlobed cormose morphology separated from the microphyll bearing axis by a smooth transition zone. This provides one of the few known examples of a cormose lycopsid rhizomorph dating back to the Devonian. We assign this material and all previously published South African Leptophloeum material to Leptophloeum rhombicum.
Upper Devonian sedimentary rocks have not, up to now, been reliably recognized cropping out in Ar... more Upper Devonian sedimentary rocks have not, up to now, been reliably recognized cropping out in Argentina. The single units considered as most probably recording the Devonian-Carboniferous transition are comprised within the La Punilla Formation, which integrates the main body of the Sierra de La Punilla, in the southwestern area of the La Rioja Province, in central-west Argentina.
Up to now, fossiliferous, Upper Devonian sedimentary rocks have not been reliably recognized crop... more Up to now, fossiliferous, Upper Devonian sedimentary rocks have not been reliably recognized cropping out in Argentina. The single units considered as most probably recording the Devonian-Carboniferous transition are comprised within the La Punilla Formation, which integrates the main body of the Sierra de La Punilla, in the southwestern area of the La Rioja Province, in central-west Argentina (Caminos et al., 1993).
![Research paper thumbnail of Early diversification of seeds and seed-like structures.[Diversification précoce des graines et structures assimilées]](https://attachments.academia-assets.com/26090548/thumbnails/1.jpg)
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Review of Palaeobotany and Palynology, Jan 1, 2006
Condrusia rumex Stockmans 1948 occurs in several localities of the Belgian Evieux Formation (late... more Condrusia rumex Stockmans 1948 occurs in several localities of the Belgian Evieux Formation (late Famennian, Upper Devonian). It consists of a hastate organ borne at the tip of "slender, dichotomizing" axes. Various interpretations have been given to this intriguing structure, ranging from a spore-bearing organ to a fern prothallus but recent investigations consider Condrusia to be an ovulate structures produced by early seed plants. The genus Condrusia includes 3 species: C. rumex Stockmans, C. minor Stockmans and C. brevis Petrosjan. C. rumex was described by Stockmans in 1948, who provided a diagnosis and illustrations, but failed to designate a holotype. We are currently reinvestigating the genus and we here designate and illustrate a lectotype for the genus and species C. rumex.
Recent Advances in …, Jan 1, 2007
The Strud quarry is located in the uppermost levels of the Dinant Synclinorium, Belgium. It expos... more The Strud quarry is located in the uppermost levels of the Dinant Synclinorium, Belgium. It exposes a part of the Upper Famennian (Upper Devonian)&amp;amp;amp;quot; Condroz sandstones&amp;amp;amp;quot;, composed mainly of fine-grained, more or less micaceous, arkosic sandstones interlayered with thin shale or siltstone beds and, but rarely, with dolomite beds (these may occur either as evaporites or as immature dolcrete)(Thorez &amp;amp;amp;amp; Dreesen, 1986).
Review of Palaeobotany …, Jan 1, 2012
A permineralized Callixylon trunk is reported from Ronquières, a mid to late Givetian (Middle Dev... more A permineralized Callixylon trunk is reported from Ronquières, a mid to late Givetian (Middle Devonian) locality from Belgium. The specimen consists of an 80 cm long trunk adpression whose central area is preserved as a pyrite permineralization. The pyritized area is composed of a eustele surrounded by secondary xylem. Tracheids show radially aligned groups of pits separated by unpitted regions on the radial walls of tracheids. The specimen belongs to a group of species characterized by a predominance of uniseriate rays and the lack of ray tracheids. This Callixylon specimen is one of the earliest representatives of the genus. It coexists at the locality with large cladoxylopsids and provides direct evidence that the tree habit had evolved in the archaeopteridalean progymnosperms by the Givetian.
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.
International Journal of Coal …, Jan 1, 2010
Early spermatophytes have been discovered at Red Hill, a Late Devonian (Famennian) fossil localit... more Early spermatophytes have been discovered at Red Hill, a Late Devonian (Famennian) fossil locality in northcentral Pennsylvania, USA. The Red Hill locality contains an Archaeopteris-dominated flora within an outcrop of the Duncannon Member of the Catskill Formation. Palynological analyses of the plant fossil-bearing horizons within the Red Hill outcrop indicate deposition within the VCo palynozone. This is the earliest time horizon known to contain evidence for spermatophytes, and is contemporaneous with well-known spermatophyte-bearing deposits in West Virginia and Belgium. Some of the spermatophyte material from Red Hill compares well with Aglosperma sp., previously known as isolated ovules from the latest Devonian of South Wales and England, thus extending its geographic and stratigraphic range. Red Hill specimens of Aglosperma sp. occur both as isolated ovules and attached to dichotomously forking axes. Additional spermatophyte cupules discovered at Red Hill are morphologically similar to those of the previously described Late Devonian spermatophytes Elkinsia Rothwell, Scheckler, et Gillespie, Moresnetia Stockmans, and Xenotheca Arber et Goode. Some of the Red Hill cupule complexes are distinct from the aforementioned taxa in consisting of slender dichotomously forking axes terminating in paired cupules with highly fused and symmetric cupule quadrant lobes. The distinctive nature of these Red Hill specimens warrants the creation of Duodimidia pfefferkornii Cressler, Prestianni, et LePage gen. et sp. nov. Plant fossil remains with sphenopteroid foliage are also present at Red Hill, possibly attributable to the spermatophytes. Previous systematic sampling of the rich plant-fossil bearing layer at Red Hill and analysis of its floristic diversity and abundance as well as the presence and absence of charcoal suggests a pattern of floral turnover from a local-scale Rhacophyton-dominated community to spermatophyte colonization following disturbance by wildfires.
Recent Advances in …, Jan 1, 2007
Palaeontologia Electronica, 2018
Morphometric characters of fossil leaves such as size and shape are important and widely used sou... more Morphometric characters of fossil leaves such as size and shape are important and widely used sources for reconstructing palaeoenvironments. Various tools, including CLAMP or Leaf Margin Analysis, utilize leaf traits as input parameters for estimating
palaeoclimate, mostly based on correlations between traits and climate parameters of extant plants. During the last few years, the scope of information extracted from the morphology of fossil leaves has been further expanded by including leaf economics, which describe correlations between functional leaf traits and ecological strategies. The amount and quality of available data are essential for a successful palaeoecological analysis utilizing leaf traits. Here, the database MORPHYLL is described. This database is devised to offer a web-based resource for fossil leaf trait data. For this purpose, fossil leaves from various collections were digitized and morphometric traits extracted from leaf outlines. Besides metadata such as accession number, repository, fossil site or taxonomic information (for identified specimens), MORPHYLL offers queries for several morphometric parameters and derived ecophysiological traits (e.g., leaf mass per area). Currently, the database contains data from about 6000 fossil leaves from sites in Central Europe, spanning almost the entire Paleogene and part of the
early Neogene. The application potential of the database is demonstrated by conducting some exemplary analyses of leaf traits for the Paleocene, Eocene and Oligocene, with the results indicating changes of mean leaf traits through time. For example, the results show leaf mass per area to peak during the Eocene, which is in accordance with general climate development during the Paleogene.
The multiovulate cupule of a new spermatophyte, Thorezia vezerensis gen. et sp. nov. , is describ... more The multiovulate cupule of a new spermatophyte,
Thorezia vezerensis
gen.
et
sp. nov.
, is described from the Late Devonian
aged sediments from Trooz Quarry in Belgium. In gross morphology, it conforms to the
Moresnetia
morphotype and has a
cupule that is composed of four independent quarters that each dichotomises three times. Each cupule quarter contains one
single ovoid preovule with a long pedicel and an integument that has small apical teeth surrounding a rudimentary
micropyle. Morphological variability in the materials examined is interpreted as being related to preovule maturity, and from
this a good understanding of the ontogenetic development from preceding dispersal has been developed. Up to now, 17
spermatophyte species have been described, 11 of which come from eastern Laurussia. This diversity in eastern Laurussia
contrasts strongly with the low diversity characterizing contemporaneous floras from other phytogeographical areas. We
suggest here that the arid climatic conditions prevailing in eastern Laurussia favoured the development of diverse
spermatophyte communities and contributed to reduced diversity and abundance of contemporaneous free-sporing plant
diversity.
Well-preserved specimens of Stauropteris oldhamia are described. The material was collected in th... more Well-preserved specimens of Stauropteris oldhamia are described. The material was collected in the early 1920s from the Lower Westphalian (Early Pennsylvanian) Saurue seam from Belgium. The fossil plants occur as permineralized axes fragments within a coal ball. This study confirms most of the interpretations made by previous researchers. The observation of immature axis however suggests a less regular organization than previously interpreted beyond the three first branching orders. We also highlight the presence of profusely and dichotomously branched aphlebiae, the lack of laminate organs as well as the presence of hypodermal aerenchyma in all plant parts. We interpret these features as part of a very specialized assimilatory apparatus indicating an adaptation to a humid swamp environment.
We review progress made during the last 25years in our understanding of the Protopityales, Early ... more We review progress made during the last 25years in our understanding of the Protopityales, Early Carboniferous plants
belonging to the extinct group of the progymnosperms. Recent studies support previous observations that the only genus of
this order,
Protopitys
, included large arborescent plant with trunks up to 1m in diameter. All branch orders had an oval
eustele, secondary xylem with small rays and tracheid pitting ranging from circular bordered to scalariform bordered, and
vascular traces to lateral appendages emitted in an alternate to subopposite distichous arrangement. Leaf morphology
remains unknown. New material also confirms that fertile organs of
Protopitys
consist of branching systems bearing
elongated sporangia terminally. Spores have a perispore and range in two size groups, which has been interpreted as a
primitive stage of heterospory. The dense wood and fertile parts of
Protopitys
are comparable to those of the
aneurophytalean progymnosperms of the Devonian, but
Protopitys
is distinct by its eustelic primary vascular system, and its
affinities are still uncertain. The genus is now documented from at least nine localities in Europe, North America and
Australia. Recent discoveries also indicate that it was present through the whole Mississippian, from the middle Tournaisian
to the Serpukhovian.
Premise of research. Although the most comprehensively known Devonian seeds were borne in a “telo... more Premise of research. Although the most comprehensively known Devonian seeds were borne in a “telomic”
cupule, those of some species have been postulated as being borne terminally on naked axes lacking a cupule.
Uncertainty remains as to whether such seeds were shed from a cupule before preservation. We reinvestigate
the Upper Devonian fossils Pseudosporogonites hallei and Xenotheca bertrandii from Belgium and the similar
ovules Aglosperma quadrapartita and Aglosperma avonensis from Britain and Aglosperma sp. from North
America to consider their structure and organization and to determine whether they were cupulate.
Methodology. Compressions/adpressions of X. bertrandii and Pseudosporogonites from Belgium and A.
quadrapartita and A. avonensis from the United Kingdom, as well as Anglosperma sp. from Pennsylvania,
were prepared, mainly by de´gagement. Observation and photography were carried out using crossed polarizing
filters.
Pivotal results. Pseudosporogonites hallei, X. bertrandii, and A. quadrapartita comprise single ovules
borne within small, radially symmetrical, uniovulate cupules. Integuments are entire at the chalaza but form
flattened lobes distally. While a cupule is unknown in A. avonensis, its comparable integument morphology
suggests that it was shed from a uniovulate cupule. Although the species are distinct from each other, their
similarities show that they are closely related and belong to a single genus, for which the name Pseudosporogonites
has priority. We emend P. hallei in light of our findings and erect the combinations P. bertrandii
(Stockmans) C. Prestianni, J. Hilton et W. Cressler, P. quadrapartitus (J. Hilton et D. Edwards) C. Prestianni,
J. Hilton et W. Cressler, and P. avonensis (J. Hilton) C. Prestianni, J. Hilton et W. Cressler.
Conclusions. The uniovulate cupule in Pseudosporogonites is distinct from multiovulate telomic cupules
of other Devonian seeds and expands the phenotypic diversity seen during the earliest phase of seed plant
radiation, which was geologically instantaneous. Hydrasperman pollination in all proven Devonian seeds
demonstrates evolution from a common ancestor, but finding morphological intermediates between seed and
free-sporing plants remains a significant challenge to evolutionary plant biology.
The Ourthe valley in eastern Belgium provides the most complete exposures of the upper Famennian ... more The Ourthe valley in eastern Belgium provides the most complete exposures of the upper Famennian Condroz Group.
A detailed miospore stratigraphy has been established for this succession. The lower three miospore biozones of the Upper Famennian
(GF, VCo and VH Oppel Zones) are re-defined and subdivided into five new interval zones. The GF Oppel Zone which spans the Middle
and Upper Famennian boundary was previously subdivided into three interval zones is now reduced to two. The highest Retispora
macroreticulata (Mac) Interval Zone is now removed (due to its very sporadic occurrence) which results in the Grandispora microseta
(Mic) Interval Zone of the GF Oppel Zone now being the lowest miospore interval zone of the Upper Famennian. The overlying
VCo Oppel zone is subdivided into two new interval zones, the Rugospora radiata (Rad) and overlying Grandispora cornuta (Cor)
interval Zones. A detailed study based on new and published material of the two nominal zonal taxa of the VCo Zone has clarified their
morphology and resolved identification problems with other closely related Upper Devonian taxa. Furthermore, a biometric comparison
of Grandispora cornuta with Grandispora tamarae has resulted in the specific diagnosis of G. cornuta being emended to increase its
minimal spine length to 8 μm. The biostratigraphic implications for intercontinental correlations with the Upper Famennian of North
America are discussed. The overlying VH Oppel Zone is subdivided into two new interval zones, the Apiculiretusispora verrucosa
(Ver) Interval Zone and the overlying Vallatisporites hystricosus (Hys) Interval Zone. All of the new miospore interval zones are closely
correlated with the well established conodont zones occurring in five sections of the Ourthe Valley. The new integrated data sets provide
a high resolution biostratigraphy for the Upper Famennian stratigraphic interval in eastern Belgium.
The rhizomorphs of Early (Devonian and Early Carboniferous) arborescent lycopsids are known from ... more The rhizomorphs of Early (Devonian and Early Carboniferous) arborescent lycopsids are known from only a handful of taxa. That of Leptophloeum is previously described from a single fragmentary specimen from China that, in our opinion, has been incorrectly interpreted. Here we describe several relatively well-preserved examples of Leptophloeum rhizomorphs from the Famennian aged Waterloo Farm Lägerstatte of South Africa. We demonstrate an unlobed cormose morphology separated from the microphyll bearing axis by a smooth transition zone. This provides one of the few known examples of a cormose lycopsid rhizomorph dating back to the Devonian. We assign this material and all previously published South African Leptophloeum material to Leptophloeum rhombicum.
Upper Devonian sedimentary rocks have not, up to now, been reliably recognized cropping out in Ar... more Upper Devonian sedimentary rocks have not, up to now, been reliably recognized cropping out in Argentina. The single units considered as most probably recording the Devonian-Carboniferous transition are comprised within the La Punilla Formation, which integrates the main body of the Sierra de La Punilla, in the southwestern area of the La Rioja Province, in central-west Argentina.
Up to now, fossiliferous, Upper Devonian sedimentary rocks have not been reliably recognized crop... more Up to now, fossiliferous, Upper Devonian sedimentary rocks have not been reliably recognized cropping out in Argentina. The single units considered as most probably recording the Devonian-Carboniferous transition are comprised within the La Punilla Formation, which integrates the main body of the Sierra de La Punilla, in the southwestern area of the La Rioja Province, in central-west Argentina (Caminos et al., 1993).
Review of Palaeobotany and Palynology, Jan 1, 2006
Condrusia rumex Stockmans 1948 occurs in several localities of the Belgian Evieux Formation (late... more Condrusia rumex Stockmans 1948 occurs in several localities of the Belgian Evieux Formation (late Famennian, Upper Devonian). It consists of a hastate organ borne at the tip of "slender, dichotomizing" axes. Various interpretations have been given to this intriguing structure, ranging from a spore-bearing organ to a fern prothallus but recent investigations consider Condrusia to be an ovulate structures produced by early seed plants. The genus Condrusia includes 3 species: C. rumex Stockmans, C. minor Stockmans and C. brevis Petrosjan. C. rumex was described by Stockmans in 1948, who provided a diagnosis and illustrations, but failed to designate a holotype. We are currently reinvestigating the genus and we here designate and illustrate a lectotype for the genus and species C. rumex.
Recent Advances in …, Jan 1, 2007
The Strud quarry is located in the uppermost levels of the Dinant Synclinorium, Belgium. It expos... more The Strud quarry is located in the uppermost levels of the Dinant Synclinorium, Belgium. It exposes a part of the Upper Famennian (Upper Devonian)&amp;amp;amp;quot; Condroz sandstones&amp;amp;amp;quot;, composed mainly of fine-grained, more or less micaceous, arkosic sandstones interlayered with thin shale or siltstone beds and, but rarely, with dolomite beds (these may occur either as evaporites or as immature dolcrete)(Thorez &amp;amp;amp;amp; Dreesen, 1986).
Review of Palaeobotany …, Jan 1, 2012
A permineralized Callixylon trunk is reported from Ronquières, a mid to late Givetian (Middle Dev... more A permineralized Callixylon trunk is reported from Ronquières, a mid to late Givetian (Middle Devonian) locality from Belgium. The specimen consists of an 80 cm long trunk adpression whose central area is preserved as a pyrite permineralization. The pyritized area is composed of a eustele surrounded by secondary xylem. Tracheids show radially aligned groups of pits separated by unpitted regions on the radial walls of tracheids. The specimen belongs to a group of species characterized by a predominance of uniseriate rays and the lack of ray tracheids. This Callixylon specimen is one of the earliest representatives of the genus. It coexists at the locality with large cladoxylopsids and provides direct evidence that the tree habit had evolved in the archaeopteridalean progymnosperms by the Givetian.
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.
International Journal of Coal …, Jan 1, 2010
Early spermatophytes have been discovered at Red Hill, a Late Devonian (Famennian) fossil localit... more Early spermatophytes have been discovered at Red Hill, a Late Devonian (Famennian) fossil locality in northcentral Pennsylvania, USA. The Red Hill locality contains an Archaeopteris-dominated flora within an outcrop of the Duncannon Member of the Catskill Formation. Palynological analyses of the plant fossil-bearing horizons within the Red Hill outcrop indicate deposition within the VCo palynozone. This is the earliest time horizon known to contain evidence for spermatophytes, and is contemporaneous with well-known spermatophyte-bearing deposits in West Virginia and Belgium. Some of the spermatophyte material from Red Hill compares well with Aglosperma sp., previously known as isolated ovules from the latest Devonian of South Wales and England, thus extending its geographic and stratigraphic range. Red Hill specimens of Aglosperma sp. occur both as isolated ovules and attached to dichotomously forking axes. Additional spermatophyte cupules discovered at Red Hill are morphologically similar to those of the previously described Late Devonian spermatophytes Elkinsia Rothwell, Scheckler, et Gillespie, Moresnetia Stockmans, and Xenotheca Arber et Goode. Some of the Red Hill cupule complexes are distinct from the aforementioned taxa in consisting of slender dichotomously forking axes terminating in paired cupules with highly fused and symmetric cupule quadrant lobes. The distinctive nature of these Red Hill specimens warrants the creation of Duodimidia pfefferkornii Cressler, Prestianni, et LePage gen. et sp. nov. Plant fossil remains with sphenopteroid foliage are also present at Red Hill, possibly attributable to the spermatophytes. Previous systematic sampling of the rich plant-fossil bearing layer at Red Hill and analysis of its floristic diversity and abundance as well as the presence and absence of charcoal suggests a pattern of floral turnover from a local-scale Rhacophyton-dominated community to spermatophyte colonization following disturbance by wildfires.
Recent Advances in …, Jan 1, 2007