The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
Brigitte Meyer-berthaud - One of the best experts on this subject based on the ideXlab platform.
-
A review of the Early Mississippian anatomically preserved flora from Montagne Noire
2020Co-Authors: Anne-laure Decombeix, Jean Galtier, Cyrille Prestianni, Brigitte Meyer-berthaud, Nick P. Rowe, Carla J. HarperAbstract:In 1870, Schimper documented an anatomically preserved lycopsid cone found near the town of Cabrières, in the Hérault region of France. Since this initial report, over 500 specimens have been collected from Tournaisian (early Mississippian) outcrops in this area. They include permineralized specimens from the radiolarian cherts and associated phosphatic nodules of the Lydiennes Formation, and a hundred compressions in argilites, some with cellular preservation. Here we provide an updated review focused on the plants from the cherts, based on a database of 441 specimens corresponding to stems (66%), leaves/petioles (27%), fertile structures (4%), and roots (1%). Seed plants are by far the most abundant and diverse group of plants and constitute approximately 64% of the specimens assignable to that group. Some genera such as Calamopitys, Stenomyelon, Tristichia, Eristophyton, Lyginorachis, Kalymma and Periastron are also found in other Late Devonian-Mississippian localities. Four genera are only documented to date in the Montagne Noire: Faironia, Lyginopitys, Triichnia, and Coumiasperma, the latter being the only seed known in the chert. Lycopsids, cladoxylopsids, and zygopteridalean ferns each represent about 10% of the specimens. Lycopsids include different types of stems and two species of Flemingites (Lepidostrobus). Cladoxylopsids are represented by stems assignable to a single genus, Cladoxylon. Zygopteridalean ferns include many types of Clepsydropsis petioles/ phyllophores; their diversification is interpreted as evidence of early radiation preceding the emergence of two clades, one leading to the quadriseriate zygopteridaleans and the other to the biseriate ankyropterid/tedeleans. The less abundant groups are the Progymnosperms and sphenopsids, each corresponding to 1-2% of the specimens. Sphenopsids are only represented by small stems of Sphenophyllum. The Progymnosperms include vegetative and fertile remains assigned to Protopitys, and the putative Progymnosperm stem Stauroxylon, which is currently being reinvestigated. The plants from the Montagne Noire constitutes one of the few well-dated middle Tournaisian floral assemblage in the world. As such, they provide key information on plant evolution, especially the diversification of ferns s.l. and seed plants. They also document floral changes between the Devonian and the Carboniferous, with the presence of a mixture of taxa belonging (1) to groups that were abundant and diverse during the Devonian and disappeared during the Carboniferous, such as the cladoxylopsids and Progymnosperms, and (2) to groups that appeared in the late Devonian and diversified to become emblematic members of Carboniferous floras, such as the Sphenophyllales, the zygopteridalean and tedelean ferns, and the seed plants.
-
Anatomically preserved plants from the Tournaisian of the Montagne Noire (France): an exceptional window into Early Mississippian floras
2019Co-Authors: Anne-laure Decombeix, Jean Galtier, Cyrille Prestianni, Brigitte Meyer-berthaud, Carla J. Harper, Hugues Terreaux De FéliceAbstract:The Mississippian was an important time in plant evolution, with the diversification of several groups, especially among the ferns s.l. and seed plants. The Montagne Noire localities in southern France include some of the oldest outcrops with anatomically preserved fossil plants from that time. The plant remains occur within the Lydienne Formation, which corresponds to alternating beds of argillaceous rock and radiolarian cherts that contain phosphatic nodules deposited in a shallow sea. The horizons containing plant fossils are considered middle Tournaisian in age based on the conodonts (Galtier et al., 1988). Since the first study of an anatomically preserved Lepidostrobus cone by Schimper in 1870, more than 30 taxa have been identified in the Lydiennes formation (e.g., Bohm, 1935; Bertrand et al., 1935; Galtier, 1970; Meyer-Berthaud, 1984; Galtier et al., 1988; Galtier & Rowe, 1989; Rowe & Galtier, 1989, 1990; Galtier et al., 1993; Decombeix et al., 2006, 2008). Ongoing work on this material aims to provide a better understanding of plant diversity in the Early Mississippian and to elucidate their systematic relationships with better-known Late Devonian and Late Mississippian taxa. Here we present (1) a synthesis of plant diversity in the Montagne Noire and how it compares to Devonian-Mississippian floras from around the world, (2) three examples of recently (re)investigated taxa and how they contribute to our understanding of plant evolution, and (3) remaining questions and future directions. The Montagne Noire anatomically preserved flora is largely dominated by seed plants, which represent more than half of the total number of collected specimens. Zygopteridalean ferns, cladoxylopsids, and lycopsids are also relatively abundant (+/- 10%) while the Progymnosperms and sphenopsids are exceptionally rare (1–2%). Reproductive structures are rare (4–5 %) and the majority of the specimens are leaves and stems (Galtier et al., 1988). The latter range from minute axes less than a millimeter in diameter to wood fragments indicating the presence of arborescent taxa. A number of genera found in the Montagne Noire also occur in younger (Late Tournaisian-Visean) localities (e.g., Stenomyelon, Eristophyton) and a few are known in both Devonian and younger Mississippian localities (e.g., Sphenophyllum, Cladoxylon). Interestingly, there are also some genera that are to date only known in the Montagne Noire such as the seed Coumiasperma, or the seed plant stems Faironia and Lyginopitys. The closest flora in terms of composition is from the Saalfeld area in Thuringia, Germany which is likely coeval. Recent (re)investigations of specimens from the Montagne Noire have provided important information on several key plant genera. One example is Sphenophyllum, a scrambling to lianescent sphenopsid genus known from the Late Devonian to the Triassic and a major component of Pennsylvanian coal swamp floras. The Montagne Noire specimens provide new information on the anatomy of Mississippian representatives of Sphenophyllum, which are poorly known in part due to the small number of permineralized specimens from that time (Terreaux de Felice et al., in revision). The Montagne Noire flora also contains several specimens that can be assigned to the enigmatic Progymnosperm Protopitys, an arborescent genus currently known from the Mississippian localities of Canada, Scotland, France, Germany, Australia, and possibly the US (Decombeix et al, 2015). Of particular importance is a branching system bearing sporangia with preserved spores. This specimen represents the third fertile specimen ever reported for the genus and is the best preserved and the oldest one known to date. Ongoing studies will provide new information and insight to assess the affinities of Protopitys. Finally, some plants from the Montagne Noire display a unique combination of characters that challenges our understanding of Devonian-Carboniferous plant relationships and their stratigraphic distribution. This is the case for Stauroxylon (Galtier 1970), an enigmatic genus currently being reexamined that could represent the youngest occurrence of an aneurophytalean Progymnosperm, a group typically known in the Middle and Late Devonian and thought to have gone extinct by the end of the Frasnian. Future work will focus on the description of unpublished specimens from the Universite de Montpellier collections and collecting of new material. While plant remains are rare in the Lydienne formation, they have the potential to provide key information on plant evolution. As one of the oldest Mississippian deposits with anatomically preserved plants, the Montagne Noire is also a crucial source of information on floral changes around the Devonian-Carboniferous boundary.
-
Anatomically preserved plants from the Tournaisian of the Montagne Noire (France): an exceptional window into Early Mississippian floras
2019Co-Authors: Anne-laure Decombeix, Jean Galtier, Cyrille Prestianni, Brigitte Meyer-berthaud, Carla J. Harper, Hugues Terreaux De FéliceAbstract:The Mississippian was an important time in plant evolution, with the diversification of several groups, especially among the ferns s.l. and seed plants. The Montagne Noire localities in southern France include some of the oldest outcrops with anatomically preserved fossil plants from that time. The plant remains occur within the Lydienne Formation, which corresponds to alternating beds of argillaceous rock and radiolarian cherts that contain phosphatic nodules deposited in a shallow sea. The horizons containing plant fossils are considered middle Tournaisian in age based on the conodonts (Galtier et al., 1988). Since the first study of an anatomically preserved Lepidostrobus cone by Schimper in 1870, more than 30 taxa have been identified in the Lydiennes formation (e.g., Böhm, 1935; Bertrand et al., 1935; Galtier, 1970; Meyer-Berthaud, 1984; Galtier et al., 1988; Galtier & Rowe, 1989; Rowe & Galtier, 1989, 1990; Galtier et al., 1993; Decombeix et al., 2006, 2008). Ongoing work on this material aims to provide a better understanding of plant diversity in the Early Mississippian and to elucidate their systematic relationships with better-known Late Devonian and Late Mississippian taxa. Here we present (1) a synthesis of plant diversity in the Montagne Noire and how it compares to Devonian-Mississippian floras from around the world, (2) three examples of recently (re)investigated taxa and how they contribute to our understanding of plant evolution, and (3) remaining questions and future directions. The Montagne Noire anatomically preserved flora is largely dominated by seed plants, which represent more than half of the total number of collected specimens. Zygopteridalean ferns, cladoxylopsids, and lycopsids are also relatively abundant (+/- 10%) while the Progymnosperms and sphenopsids are exceptionally rare (1–2%). Reproductive structures are rare (4–5 %) and the majority of the specimens are leaves and stems (Galtier et al., 1988). The latter range from minute axes less than a millimeter in diameter to wood fragments indicating the presence of arborescent taxa. A number of genera found in the Montagne Noire also occur in younger (Late Tournaisian-Viséan) localities (e.g., Stenomyelon, Eristophyton) and a few are known in both Devonian and younger Mississippian localities (e.g., Sphenophyllum, Cladoxylon). Interestingly, there are also some genera that are to date only known in the Montagne Noire such as the seed Coumiasperma, or the seed plant stems Faironia and Lyginopitys. The closest flora in terms of composition is from the Saalfeld area in Thuringia, Germany which is likely coeval. Recent (re)investigations of specimens from the Montagne Noire have provided important information on several key plant genera. One example is Sphenophyllum, a scrambling to lianescent sphenopsid genus known from the Late Devonian to the Triassic and a major component of Pennsylvanian coal swamp floras. The Montagne Noire specimens provide new information on the anatomy of Mississippian representatives of Sphenophyllum, which are poorly known in part due to the small number of permineralized specimens from that time (Terreaux de Félice et al., in revision). The Montagne Noire flora also contains several specimens that can be assigned to the enigmatic Progymnosperm Protopitys, an arborescent genus currently known from the Mississippian localities of Canada, Scotland, France, Germany, Australia, and possibly the US (Decombeix et al, 2015). Of particular importance is a branching system bearing sporangia with preserved spores. This specimen represents the third fertile specimen ever reported for the genus and is the best preserved and the oldest one known to date. Ongoing studies will provide new information and insight to assess the affinities of Protopitys. Finally, some plants from the Montagne Noire display a unique combination of characters that challenges our understanding of Devonian-Carboniferous plant relationships and their stratigraphic distribution. This is the case for Stauroxylon (Galtier 1970), an enigmatic genus currently being reexamined that could represent the youngest occurrence of an aneurophytalean Progymnosperm, a group typically known in the Middle and Late Devonian and thought to have gone extinct by the end of the Frasnian. Future work will focus on the description of unpublished specimens from the Université de Montpellier collections and collecting of new material. While plant remains are rare in the Lydienne formation, they have the potential to provide key information on plant evolution. As one of the oldest Mississippian deposits with anatomically preserved plants, the Montagne Noire is also a crucial source of information on floral changes around the Devonian-Carboniferous boundary.
-
Whose Roots Are These? Linking Anatomically Preserved Lignophyte Roots and Stems from the Early Carboniferous of Montagne Noire, France
International Journal of Plant Sciences, 2017Co-Authors: Anne-laure Decombeix, Dorothée Letellier, Brigitte Meyer-berthaudAbstract:International audienceDespite their importance for understanding plant evolution and plant-environmental interactions through geological time, fossil roots have always received less attention than aerial parts. In the case of the lignophytes (i.e., Progymnosperms and seed plants), the ability to form abundant secondary vascular tissues (secondary xylem and phloem) can, however, provide useful characters to compare isolated roots to stems from the same deposit to better understand the whole-plant structure and function of fossil plants.Methodology.We studied five permineralized lignophyte roots with well-preserved secondary xylem, and in two cases some secondary phloem, from the Early Carboniferous Lydiennes Formation of the Montagne Noire, France, using classical thin sections.Pivotal results.Analysis of the secondary vascular tissues of the roots allows us to distinguish three wood morphotypes that suggest affinities with at least three different types of stems previously reported in the Montagne Noire. One specimen is assigned to the arborescent seed plant Eristophyton; two are assigned to small, probably non-self-supporting seed plants belonging to either the Calamopityaceae or Lyginopitys; and two are assigned to the Progymnosperms Protopitys or Stauroxylon.Conclusions.This study illustrates how the affinities of isolated permineralized lignophyte roots can be narrowed down by comparing their wood anatomy with that of stems from the same deposit. The diversity of stem organization seen in the Montagne Noire deposit typically illustrates the morpho-anatomical diversification of the lignophytes’ vegetative body in the Early Carboniferous. This study is a first step toward adding the underground organs to our understanding of this diversification
-
Callixylon wendtii sp. nov., a new species of archaeopteridalean Progymnosperm from the Late Devonian of Anti-Atlas, Morocco
Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 2017Co-Authors: Mélanie Tanrattana, Brigitte Meyer-berthaud, Anne-laure DecombeixAbstract:Archaeopterid trees were the main components of most Late Devonian forests. Their aerial axes characterised by a eustele with mesarch primary xylem strands, leaf traces departing radially from cauline bundles and secondary xylem tracheids with radial pits arranged in groups, are referred to the genus Callixylon Zalessky. The nineteen species of Callixylon described to date from North America, North Africa, Europe, Xinjiang and several parts of Russia range from the late Givetian to the Mississippian. In this paper, we describe a new species of Callixylon from two specimens collected in the Famennian locality of Mader el Mrakib in eastern Anti-Atlas. Callixylon wendtii sp. nov. is characterised by the presence of sclerotic nests in the pith, a new character for the genus. Its wood shows narrow rays of variable height, with unevenly distributed ray tracheids. Small vascular traces crossing the wood within the two innermost growth rings are interpreted as evidence for short-lived leaves. This discovery adds to the diversity of the genus Callixylon in an area of northern Gondwana that may have been favourable to the establishment of a diverse community of archaeopterid trees.
Jean Galtier - One of the best experts on this subject based on the ideXlab platform.
-
A review of the Early Mississippian anatomically preserved flora from Montagne Noire
2020Co-Authors: Anne-laure Decombeix, Jean Galtier, Cyrille Prestianni, Brigitte Meyer-berthaud, Nick P. Rowe, Carla J. HarperAbstract:In 1870, Schimper documented an anatomically preserved lycopsid cone found near the town of Cabrières, in the Hérault region of France. Since this initial report, over 500 specimens have been collected from Tournaisian (early Mississippian) outcrops in this area. They include permineralized specimens from the radiolarian cherts and associated phosphatic nodules of the Lydiennes Formation, and a hundred compressions in argilites, some with cellular preservation. Here we provide an updated review focused on the plants from the cherts, based on a database of 441 specimens corresponding to stems (66%), leaves/petioles (27%), fertile structures (4%), and roots (1%). Seed plants are by far the most abundant and diverse group of plants and constitute approximately 64% of the specimens assignable to that group. Some genera such as Calamopitys, Stenomyelon, Tristichia, Eristophyton, Lyginorachis, Kalymma and Periastron are also found in other Late Devonian-Mississippian localities. Four genera are only documented to date in the Montagne Noire: Faironia, Lyginopitys, Triichnia, and Coumiasperma, the latter being the only seed known in the chert. Lycopsids, cladoxylopsids, and zygopteridalean ferns each represent about 10% of the specimens. Lycopsids include different types of stems and two species of Flemingites (Lepidostrobus). Cladoxylopsids are represented by stems assignable to a single genus, Cladoxylon. Zygopteridalean ferns include many types of Clepsydropsis petioles/ phyllophores; their diversification is interpreted as evidence of early radiation preceding the emergence of two clades, one leading to the quadriseriate zygopteridaleans and the other to the biseriate ankyropterid/tedeleans. The less abundant groups are the Progymnosperms and sphenopsids, each corresponding to 1-2% of the specimens. Sphenopsids are only represented by small stems of Sphenophyllum. The Progymnosperms include vegetative and fertile remains assigned to Protopitys, and the putative Progymnosperm stem Stauroxylon, which is currently being reinvestigated. The plants from the Montagne Noire constitutes one of the few well-dated middle Tournaisian floral assemblage in the world. As such, they provide key information on plant evolution, especially the diversification of ferns s.l. and seed plants. They also document floral changes between the Devonian and the Carboniferous, with the presence of a mixture of taxa belonging (1) to groups that were abundant and diverse during the Devonian and disappeared during the Carboniferous, such as the cladoxylopsids and Progymnosperms, and (2) to groups that appeared in the late Devonian and diversified to become emblematic members of Carboniferous floras, such as the Sphenophyllales, the zygopteridalean and tedelean ferns, and the seed plants.
-
Anatomically preserved plants from the Tournaisian of the Montagne Noire (France): an exceptional window into Early Mississippian floras
2019Co-Authors: Anne-laure Decombeix, Jean Galtier, Cyrille Prestianni, Brigitte Meyer-berthaud, Carla J. Harper, Hugues Terreaux De FéliceAbstract:The Mississippian was an important time in plant evolution, with the diversification of several groups, especially among the ferns s.l. and seed plants. The Montagne Noire localities in southern France include some of the oldest outcrops with anatomically preserved fossil plants from that time. The plant remains occur within the Lydienne Formation, which corresponds to alternating beds of argillaceous rock and radiolarian cherts that contain phosphatic nodules deposited in a shallow sea. The horizons containing plant fossils are considered middle Tournaisian in age based on the conodonts (Galtier et al., 1988). Since the first study of an anatomically preserved Lepidostrobus cone by Schimper in 1870, more than 30 taxa have been identified in the Lydiennes formation (e.g., Böhm, 1935; Bertrand et al., 1935; Galtier, 1970; Meyer-Berthaud, 1984; Galtier et al., 1988; Galtier & Rowe, 1989; Rowe & Galtier, 1989, 1990; Galtier et al., 1993; Decombeix et al., 2006, 2008). Ongoing work on this material aims to provide a better understanding of plant diversity in the Early Mississippian and to elucidate their systematic relationships with better-known Late Devonian and Late Mississippian taxa. Here we present (1) a synthesis of plant diversity in the Montagne Noire and how it compares to Devonian-Mississippian floras from around the world, (2) three examples of recently (re)investigated taxa and how they contribute to our understanding of plant evolution, and (3) remaining questions and future directions. The Montagne Noire anatomically preserved flora is largely dominated by seed plants, which represent more than half of the total number of collected specimens. Zygopteridalean ferns, cladoxylopsids, and lycopsids are also relatively abundant (+/- 10%) while the Progymnosperms and sphenopsids are exceptionally rare (1–2%). Reproductive structures are rare (4–5 %) and the majority of the specimens are leaves and stems (Galtier et al., 1988). The latter range from minute axes less than a millimeter in diameter to wood fragments indicating the presence of arborescent taxa. A number of genera found in the Montagne Noire also occur in younger (Late Tournaisian-Viséan) localities (e.g., Stenomyelon, Eristophyton) and a few are known in both Devonian and younger Mississippian localities (e.g., Sphenophyllum, Cladoxylon). Interestingly, there are also some genera that are to date only known in the Montagne Noire such as the seed Coumiasperma, or the seed plant stems Faironia and Lyginopitys. The closest flora in terms of composition is from the Saalfeld area in Thuringia, Germany which is likely coeval. Recent (re)investigations of specimens from the Montagne Noire have provided important information on several key plant genera. One example is Sphenophyllum, a scrambling to lianescent sphenopsid genus known from the Late Devonian to the Triassic and a major component of Pennsylvanian coal swamp floras. The Montagne Noire specimens provide new information on the anatomy of Mississippian representatives of Sphenophyllum, which are poorly known in part due to the small number of permineralized specimens from that time (Terreaux de Félice et al., in revision). The Montagne Noire flora also contains several specimens that can be assigned to the enigmatic Progymnosperm Protopitys, an arborescent genus currently known from the Mississippian localities of Canada, Scotland, France, Germany, Australia, and possibly the US (Decombeix et al, 2015). Of particular importance is a branching system bearing sporangia with preserved spores. This specimen represents the third fertile specimen ever reported for the genus and is the best preserved and the oldest one known to date. Ongoing studies will provide new information and insight to assess the affinities of Protopitys. Finally, some plants from the Montagne Noire display a unique combination of characters that challenges our understanding of Devonian-Carboniferous plant relationships and their stratigraphic distribution. This is the case for Stauroxylon (Galtier 1970), an enigmatic genus currently being reexamined that could represent the youngest occurrence of an aneurophytalean Progymnosperm, a group typically known in the Middle and Late Devonian and thought to have gone extinct by the end of the Frasnian. Future work will focus on the description of unpublished specimens from the Université de Montpellier collections and collecting of new material. While plant remains are rare in the Lydienne formation, they have the potential to provide key information on plant evolution. As one of the oldest Mississippian deposits with anatomically preserved plants, the Montagne Noire is also a crucial source of information on floral changes around the Devonian-Carboniferous boundary.
-
Anatomically preserved plants from the Tournaisian of the Montagne Noire (France): an exceptional window into Early Mississippian floras
2019Co-Authors: Anne-laure Decombeix, Jean Galtier, Cyrille Prestianni, Brigitte Meyer-berthaud, Carla J. Harper, Hugues Terreaux De FéliceAbstract:The Mississippian was an important time in plant evolution, with the diversification of several groups, especially among the ferns s.l. and seed plants. The Montagne Noire localities in southern France include some of the oldest outcrops with anatomically preserved fossil plants from that time. The plant remains occur within the Lydienne Formation, which corresponds to alternating beds of argillaceous rock and radiolarian cherts that contain phosphatic nodules deposited in a shallow sea. The horizons containing plant fossils are considered middle Tournaisian in age based on the conodonts (Galtier et al., 1988). Since the first study of an anatomically preserved Lepidostrobus cone by Schimper in 1870, more than 30 taxa have been identified in the Lydiennes formation (e.g., Bohm, 1935; Bertrand et al., 1935; Galtier, 1970; Meyer-Berthaud, 1984; Galtier et al., 1988; Galtier & Rowe, 1989; Rowe & Galtier, 1989, 1990; Galtier et al., 1993; Decombeix et al., 2006, 2008). Ongoing work on this material aims to provide a better understanding of plant diversity in the Early Mississippian and to elucidate their systematic relationships with better-known Late Devonian and Late Mississippian taxa. Here we present (1) a synthesis of plant diversity in the Montagne Noire and how it compares to Devonian-Mississippian floras from around the world, (2) three examples of recently (re)investigated taxa and how they contribute to our understanding of plant evolution, and (3) remaining questions and future directions. The Montagne Noire anatomically preserved flora is largely dominated by seed plants, which represent more than half of the total number of collected specimens. Zygopteridalean ferns, cladoxylopsids, and lycopsids are also relatively abundant (+/- 10%) while the Progymnosperms and sphenopsids are exceptionally rare (1–2%). Reproductive structures are rare (4–5 %) and the majority of the specimens are leaves and stems (Galtier et al., 1988). The latter range from minute axes less than a millimeter in diameter to wood fragments indicating the presence of arborescent taxa. A number of genera found in the Montagne Noire also occur in younger (Late Tournaisian-Visean) localities (e.g., Stenomyelon, Eristophyton) and a few are known in both Devonian and younger Mississippian localities (e.g., Sphenophyllum, Cladoxylon). Interestingly, there are also some genera that are to date only known in the Montagne Noire such as the seed Coumiasperma, or the seed plant stems Faironia and Lyginopitys. The closest flora in terms of composition is from the Saalfeld area in Thuringia, Germany which is likely coeval. Recent (re)investigations of specimens from the Montagne Noire have provided important information on several key plant genera. One example is Sphenophyllum, a scrambling to lianescent sphenopsid genus known from the Late Devonian to the Triassic and a major component of Pennsylvanian coal swamp floras. The Montagne Noire specimens provide new information on the anatomy of Mississippian representatives of Sphenophyllum, which are poorly known in part due to the small number of permineralized specimens from that time (Terreaux de Felice et al., in revision). The Montagne Noire flora also contains several specimens that can be assigned to the enigmatic Progymnosperm Protopitys, an arborescent genus currently known from the Mississippian localities of Canada, Scotland, France, Germany, Australia, and possibly the US (Decombeix et al, 2015). Of particular importance is a branching system bearing sporangia with preserved spores. This specimen represents the third fertile specimen ever reported for the genus and is the best preserved and the oldest one known to date. Ongoing studies will provide new information and insight to assess the affinities of Protopitys. Finally, some plants from the Montagne Noire display a unique combination of characters that challenges our understanding of Devonian-Carboniferous plant relationships and their stratigraphic distribution. This is the case for Stauroxylon (Galtier 1970), an enigmatic genus currently being reexamined that could represent the youngest occurrence of an aneurophytalean Progymnosperm, a group typically known in the Middle and Late Devonian and thought to have gone extinct by the end of the Frasnian. Future work will focus on the description of unpublished specimens from the Universite de Montpellier collections and collecting of new material. While plant remains are rare in the Lydienne formation, they have the potential to provide key information on plant evolution. As one of the oldest Mississippian deposits with anatomically preserved plants, the Montagne Noire is also a crucial source of information on floral changes around the Devonian-Carboniferous boundary.
-
Ahnetia, a new lignophyte stem from the Lower Carboniferous of southern Algeria
Review of Palaeobotany and Palynology, 2017Co-Authors: Anne-laure Decombeix, Jean GaltierAbstract:A new taxon of lignophyte is described based on a permineralized stem from the Late Tournaisian (Lower Carboniferous) of the Central Ahnet region, Algeria. It shows similarities with arborescent seed plants described in the Lower Carboniferous of Europe and North America such as Eristophyton waltonii Lacey and Cauloxylon ambiguum Cribbs. However, the primary and secondary vascular system of the stem display an original combination of characters and it is assigned to a new genus: Ahnetia. The preservation of extraxylary tissues (secondary phloem, periderm, cortex) allows formulating hypotheses on the stem's growth potential. The early appearance of a periderm indicates that Ahnetia was capable of significant secondary growth and that the specimen likely represents a young axis of a larger plant. By its Late Tournaisian age, this specimen represents the oldest known occurrence in North Africa of a lignophyte capable of significant secondary growth after the extinction of the Progymnosperm Archaeopteris.
-
Ahnetia, a new lignophyte stem from the Lower Carboniferous of southern Algeria
Review of Palaeobotany and Palynology, 2017Co-Authors: Anne-laure Decombeix, Jean GaltierAbstract:International audienceA new taxon of lignophyte is described based on a permineralized stem from the Late Tournaisian (Lower Carboniferous) of the Central Ahnet region, Algeria. It shows similarities with arborescent seed plants described in the Lower Carboniferous of Europe and North America such as Eristophyton waltonii Lacey and Cauloxylon ambiguum Cribbs. However, the primary and secondary vascular system of the stem display an original combination of characters and it is assigned to a new genus: Ahnetia. The preservation of extraxylary tissues (secondary phloem, periderm, cortex) allows formulating hypotheses on the stem's growth potential. The early appearance of a periderm indicates that Ahnetia was capable of significant secondary growth and that the specimen likely represents a young axis of a larger plant. By its Late Tournaisian age, this specimen represents the oldest known occurrence in North Africa of a lignophyte capable of significant secondary growth after the extinction of the Progymnosperm Archaeopteris
Anne-laure Decombeix - One of the best experts on this subject based on the ideXlab platform.
-
A review of the Early Mississippian anatomically preserved flora from Montagne Noire
2020Co-Authors: Anne-laure Decombeix, Jean Galtier, Cyrille Prestianni, Brigitte Meyer-berthaud, Nick P. Rowe, Carla J. HarperAbstract:In 1870, Schimper documented an anatomically preserved lycopsid cone found near the town of Cabrières, in the Hérault region of France. Since this initial report, over 500 specimens have been collected from Tournaisian (early Mississippian) outcrops in this area. They include permineralized specimens from the radiolarian cherts and associated phosphatic nodules of the Lydiennes Formation, and a hundred compressions in argilites, some with cellular preservation. Here we provide an updated review focused on the plants from the cherts, based on a database of 441 specimens corresponding to stems (66%), leaves/petioles (27%), fertile structures (4%), and roots (1%). Seed plants are by far the most abundant and diverse group of plants and constitute approximately 64% of the specimens assignable to that group. Some genera such as Calamopitys, Stenomyelon, Tristichia, Eristophyton, Lyginorachis, Kalymma and Periastron are also found in other Late Devonian-Mississippian localities. Four genera are only documented to date in the Montagne Noire: Faironia, Lyginopitys, Triichnia, and Coumiasperma, the latter being the only seed known in the chert. Lycopsids, cladoxylopsids, and zygopteridalean ferns each represent about 10% of the specimens. Lycopsids include different types of stems and two species of Flemingites (Lepidostrobus). Cladoxylopsids are represented by stems assignable to a single genus, Cladoxylon. Zygopteridalean ferns include many types of Clepsydropsis petioles/ phyllophores; their diversification is interpreted as evidence of early radiation preceding the emergence of two clades, one leading to the quadriseriate zygopteridaleans and the other to the biseriate ankyropterid/tedeleans. The less abundant groups are the Progymnosperms and sphenopsids, each corresponding to 1-2% of the specimens. Sphenopsids are only represented by small stems of Sphenophyllum. The Progymnosperms include vegetative and fertile remains assigned to Protopitys, and the putative Progymnosperm stem Stauroxylon, which is currently being reinvestigated. The plants from the Montagne Noire constitutes one of the few well-dated middle Tournaisian floral assemblage in the world. As such, they provide key information on plant evolution, especially the diversification of ferns s.l. and seed plants. They also document floral changes between the Devonian and the Carboniferous, with the presence of a mixture of taxa belonging (1) to groups that were abundant and diverse during the Devonian and disappeared during the Carboniferous, such as the cladoxylopsids and Progymnosperms, and (2) to groups that appeared in the late Devonian and diversified to become emblematic members of Carboniferous floras, such as the Sphenophyllales, the zygopteridalean and tedelean ferns, and the seed plants.
-
Anatomically preserved plants from the Tournaisian of the Montagne Noire (France): an exceptional window into Early Mississippian floras
2019Co-Authors: Anne-laure Decombeix, Jean Galtier, Cyrille Prestianni, Brigitte Meyer-berthaud, Carla J. Harper, Hugues Terreaux De FéliceAbstract:The Mississippian was an important time in plant evolution, with the diversification of several groups, especially among the ferns s.l. and seed plants. The Montagne Noire localities in southern France include some of the oldest outcrops with anatomically preserved fossil plants from that time. The plant remains occur within the Lydienne Formation, which corresponds to alternating beds of argillaceous rock and radiolarian cherts that contain phosphatic nodules deposited in a shallow sea. The horizons containing plant fossils are considered middle Tournaisian in age based on the conodonts (Galtier et al., 1988). Since the first study of an anatomically preserved Lepidostrobus cone by Schimper in 1870, more than 30 taxa have been identified in the Lydiennes formation (e.g., Bohm, 1935; Bertrand et al., 1935; Galtier, 1970; Meyer-Berthaud, 1984; Galtier et al., 1988; Galtier & Rowe, 1989; Rowe & Galtier, 1989, 1990; Galtier et al., 1993; Decombeix et al., 2006, 2008). Ongoing work on this material aims to provide a better understanding of plant diversity in the Early Mississippian and to elucidate their systematic relationships with better-known Late Devonian and Late Mississippian taxa. Here we present (1) a synthesis of plant diversity in the Montagne Noire and how it compares to Devonian-Mississippian floras from around the world, (2) three examples of recently (re)investigated taxa and how they contribute to our understanding of plant evolution, and (3) remaining questions and future directions. The Montagne Noire anatomically preserved flora is largely dominated by seed plants, which represent more than half of the total number of collected specimens. Zygopteridalean ferns, cladoxylopsids, and lycopsids are also relatively abundant (+/- 10%) while the Progymnosperms and sphenopsids are exceptionally rare (1–2%). Reproductive structures are rare (4–5 %) and the majority of the specimens are leaves and stems (Galtier et al., 1988). The latter range from minute axes less than a millimeter in diameter to wood fragments indicating the presence of arborescent taxa. A number of genera found in the Montagne Noire also occur in younger (Late Tournaisian-Visean) localities (e.g., Stenomyelon, Eristophyton) and a few are known in both Devonian and younger Mississippian localities (e.g., Sphenophyllum, Cladoxylon). Interestingly, there are also some genera that are to date only known in the Montagne Noire such as the seed Coumiasperma, or the seed plant stems Faironia and Lyginopitys. The closest flora in terms of composition is from the Saalfeld area in Thuringia, Germany which is likely coeval. Recent (re)investigations of specimens from the Montagne Noire have provided important information on several key plant genera. One example is Sphenophyllum, a scrambling to lianescent sphenopsid genus known from the Late Devonian to the Triassic and a major component of Pennsylvanian coal swamp floras. The Montagne Noire specimens provide new information on the anatomy of Mississippian representatives of Sphenophyllum, which are poorly known in part due to the small number of permineralized specimens from that time (Terreaux de Felice et al., in revision). The Montagne Noire flora also contains several specimens that can be assigned to the enigmatic Progymnosperm Protopitys, an arborescent genus currently known from the Mississippian localities of Canada, Scotland, France, Germany, Australia, and possibly the US (Decombeix et al, 2015). Of particular importance is a branching system bearing sporangia with preserved spores. This specimen represents the third fertile specimen ever reported for the genus and is the best preserved and the oldest one known to date. Ongoing studies will provide new information and insight to assess the affinities of Protopitys. Finally, some plants from the Montagne Noire display a unique combination of characters that challenges our understanding of Devonian-Carboniferous plant relationships and their stratigraphic distribution. This is the case for Stauroxylon (Galtier 1970), an enigmatic genus currently being reexamined that could represent the youngest occurrence of an aneurophytalean Progymnosperm, a group typically known in the Middle and Late Devonian and thought to have gone extinct by the end of the Frasnian. Future work will focus on the description of unpublished specimens from the Universite de Montpellier collections and collecting of new material. While plant remains are rare in the Lydienne formation, they have the potential to provide key information on plant evolution. As one of the oldest Mississippian deposits with anatomically preserved plants, the Montagne Noire is also a crucial source of information on floral changes around the Devonian-Carboniferous boundary.
-
Anatomically preserved plants from the Tournaisian of the Montagne Noire (France): an exceptional window into Early Mississippian floras
2019Co-Authors: Anne-laure Decombeix, Jean Galtier, Cyrille Prestianni, Brigitte Meyer-berthaud, Carla J. Harper, Hugues Terreaux De FéliceAbstract:The Mississippian was an important time in plant evolution, with the diversification of several groups, especially among the ferns s.l. and seed plants. The Montagne Noire localities in southern France include some of the oldest outcrops with anatomically preserved fossil plants from that time. The plant remains occur within the Lydienne Formation, which corresponds to alternating beds of argillaceous rock and radiolarian cherts that contain phosphatic nodules deposited in a shallow sea. The horizons containing plant fossils are considered middle Tournaisian in age based on the conodonts (Galtier et al., 1988). Since the first study of an anatomically preserved Lepidostrobus cone by Schimper in 1870, more than 30 taxa have been identified in the Lydiennes formation (e.g., Böhm, 1935; Bertrand et al., 1935; Galtier, 1970; Meyer-Berthaud, 1984; Galtier et al., 1988; Galtier & Rowe, 1989; Rowe & Galtier, 1989, 1990; Galtier et al., 1993; Decombeix et al., 2006, 2008). Ongoing work on this material aims to provide a better understanding of plant diversity in the Early Mississippian and to elucidate their systematic relationships with better-known Late Devonian and Late Mississippian taxa. Here we present (1) a synthesis of plant diversity in the Montagne Noire and how it compares to Devonian-Mississippian floras from around the world, (2) three examples of recently (re)investigated taxa and how they contribute to our understanding of plant evolution, and (3) remaining questions and future directions. The Montagne Noire anatomically preserved flora is largely dominated by seed plants, which represent more than half of the total number of collected specimens. Zygopteridalean ferns, cladoxylopsids, and lycopsids are also relatively abundant (+/- 10%) while the Progymnosperms and sphenopsids are exceptionally rare (1–2%). Reproductive structures are rare (4–5 %) and the majority of the specimens are leaves and stems (Galtier et al., 1988). The latter range from minute axes less than a millimeter in diameter to wood fragments indicating the presence of arborescent taxa. A number of genera found in the Montagne Noire also occur in younger (Late Tournaisian-Viséan) localities (e.g., Stenomyelon, Eristophyton) and a few are known in both Devonian and younger Mississippian localities (e.g., Sphenophyllum, Cladoxylon). Interestingly, there are also some genera that are to date only known in the Montagne Noire such as the seed Coumiasperma, or the seed plant stems Faironia and Lyginopitys. The closest flora in terms of composition is from the Saalfeld area in Thuringia, Germany which is likely coeval. Recent (re)investigations of specimens from the Montagne Noire have provided important information on several key plant genera. One example is Sphenophyllum, a scrambling to lianescent sphenopsid genus known from the Late Devonian to the Triassic and a major component of Pennsylvanian coal swamp floras. The Montagne Noire specimens provide new information on the anatomy of Mississippian representatives of Sphenophyllum, which are poorly known in part due to the small number of permineralized specimens from that time (Terreaux de Félice et al., in revision). The Montagne Noire flora also contains several specimens that can be assigned to the enigmatic Progymnosperm Protopitys, an arborescent genus currently known from the Mississippian localities of Canada, Scotland, France, Germany, Australia, and possibly the US (Decombeix et al, 2015). Of particular importance is a branching system bearing sporangia with preserved spores. This specimen represents the third fertile specimen ever reported for the genus and is the best preserved and the oldest one known to date. Ongoing studies will provide new information and insight to assess the affinities of Protopitys. Finally, some plants from the Montagne Noire display a unique combination of characters that challenges our understanding of Devonian-Carboniferous plant relationships and their stratigraphic distribution. This is the case for Stauroxylon (Galtier 1970), an enigmatic genus currently being reexamined that could represent the youngest occurrence of an aneurophytalean Progymnosperm, a group typically known in the Middle and Late Devonian and thought to have gone extinct by the end of the Frasnian. Future work will focus on the description of unpublished specimens from the Université de Montpellier collections and collecting of new material. While plant remains are rare in the Lydienne formation, they have the potential to provide key information on plant evolution. As one of the oldest Mississippian deposits with anatomically preserved plants, the Montagne Noire is also a crucial source of information on floral changes around the Devonian-Carboniferous boundary.
-
Whose Roots Are These? Linking Anatomically Preserved Lignophyte Roots and Stems from the Early Carboniferous of Montagne Noire, France
International Journal of Plant Sciences, 2017Co-Authors: Anne-laure Decombeix, Dorothée Letellier, Brigitte Meyer-berthaudAbstract:International audienceDespite their importance for understanding plant evolution and plant-environmental interactions through geological time, fossil roots have always received less attention than aerial parts. In the case of the lignophytes (i.e., Progymnosperms and seed plants), the ability to form abundant secondary vascular tissues (secondary xylem and phloem) can, however, provide useful characters to compare isolated roots to stems from the same deposit to better understand the whole-plant structure and function of fossil plants.Methodology.We studied five permineralized lignophyte roots with well-preserved secondary xylem, and in two cases some secondary phloem, from the Early Carboniferous Lydiennes Formation of the Montagne Noire, France, using classical thin sections.Pivotal results.Analysis of the secondary vascular tissues of the roots allows us to distinguish three wood morphotypes that suggest affinities with at least three different types of stems previously reported in the Montagne Noire. One specimen is assigned to the arborescent seed plant Eristophyton; two are assigned to small, probably non-self-supporting seed plants belonging to either the Calamopityaceae or Lyginopitys; and two are assigned to the Progymnosperms Protopitys or Stauroxylon.Conclusions.This study illustrates how the affinities of isolated permineralized lignophyte roots can be narrowed down by comparing their wood anatomy with that of stems from the same deposit. The diversity of stem organization seen in the Montagne Noire deposit typically illustrates the morpho-anatomical diversification of the lignophytes’ vegetative body in the Early Carboniferous. This study is a first step toward adding the underground organs to our understanding of this diversification
-
Ahnetia, a new lignophyte stem from the Lower Carboniferous of southern Algeria
Review of Palaeobotany and Palynology, 2017Co-Authors: Anne-laure Decombeix, Jean GaltierAbstract:A new taxon of lignophyte is described based on a permineralized stem from the Late Tournaisian (Lower Carboniferous) of the Central Ahnet region, Algeria. It shows similarities with arborescent seed plants described in the Lower Carboniferous of Europe and North America such as Eristophyton waltonii Lacey and Cauloxylon ambiguum Cribbs. However, the primary and secondary vascular system of the stem display an original combination of characters and it is assigned to a new genus: Ahnetia. The preservation of extraxylary tissues (secondary phloem, periderm, cortex) allows formulating hypotheses on the stem's growth potential. The early appearance of a periderm indicates that Ahnetia was capable of significant secondary growth and that the specimen likely represents a young axis of a larger plant. By its Late Tournaisian age, this specimen represents the oldest known occurrence in North Africa of a lignophyte capable of significant secondary growth after the extinction of the Progymnosperm Archaeopteris.
Hubert Lardeux - One of the best experts on this subject based on the ideXlab platform.
-
Frasnian plants from the Dra Valley, southern Anti-Atlas, Morocco
Geological Magazine, 2004Co-Authors: Brigitte Meyer-berthaud, Martin Rücklin, Aude Soria, Zdzislaw Belka, Hubert LardeuxAbstract:Anatomically preserved plant fragments are reported from Devonian marine deposits exposed in the Dra Valley of southern Anti-Atlas, Morocco. Associated conodont and tentaculite faunas indicate that the sediments yielding plants, which consist of black shales with intercalated calcareous concretions, are early Frasnian in age and most probably represent Zone 2 of the conodont zonation. This is the first record of Frasnian plants in North Africa. The specimens found all correspond to decorticated portions of axes. Six are referable to Callixylon, the organ genus corresponding to anatomically preserved axes of the Progymnosperm tree Archaeopteris. Based on wood characters, especially ray structure, they are assigned to the species C. henkei, formerly described from the Famennian of Europe. One single specimen is compared to Xenocladia, a cladoxylopsid genus previously known from the Middle Devonian of Europe, USA and Kazakhstan. Interestingly, Archaeopteridales and Cladoxylopsida are two groups that dominate the younger plant assemblages of Famennian age recently described from the eastern Anti-Atlas. Callixylon henkei-type axes occur both in the Frasnian and in the Famennian deposits of the Anti-Atlas and they are all devoid of growth rings. These results are in accordance with a close position of Gondwana and Euramerica during Late Devonian times.
-
DOI: 10.1017/S0016756804009665 Printed in the United Kingdom Frasnian plants from the Dra Valley, southern Anti-Atlas, Morocco
2004Co-Authors: Brigitte Meyer-berthaud, Aude Soria, Zdzislaw Belka, Hubert LardeuxAbstract:Abstract – Anatomically preserved plant fragments are reported from Devonian marine deposits exposed in the Dra Valley of southern Anti-Atlas, Morocco. Associated conodont and tentaculite faunas indicate that the sediments yielding plants, which consist of black shales with intercalated calcareous concretions, are early Frasnian in age and most probably represent Zone 2 of the conodont zonation. This is the first record of Frasnian plants in North Africa. The specimens found all correspond to decorticated portions of axes. Six are referable to Callixylon, the organ genus corresponding to anatomically preserved axes of the Progymnosperm tree Archaeopteris. Based on wood characters, especially ray structure, they are assigned to the species C. henkei, formerly described from the Famennian of Europe. One single specimen is compared to Xenocladia, a cladoxylopsid genus previously known from the Middle Devonian of Europe, USA and Kazakhstan. Interestingly, Archaeopteridales and Cladoxylopsida are two groups that dominate the younger plant assemblages of Famennian age recently described from the eastern Anti-Atlas. Callixylon henkei-type axes occur both in the Frasnian and in the Famennian deposits of the Anti-Atlas and they are all devoid of growth rings. These results are in accordance with a close position of Gondwana and Euramerica during Late Devonian times
Howard J. Falcon-lang - One of the best experts on this subject based on the ideXlab platform.
-
Anatomically-preserved tree-trunks in late Mississippian (Serpukhovian, late Pendleian–Arnsbergian) braided fluvial channel facies, near Searston, southwest Newfoundland, Canada
Review of Palaeobotany and Palynology, 2010Co-Authors: Howard J. Falcon-lang, Jean GaltierAbstract:Abstract Little is known of the Mississippian palaeobotany of Newfoundland, Canada. Here we improve this situation by describing anatomically-preserved tree-trunks from the Codroy Valley, southwest Newfoundland. The tree-trunks, which have incomplete lengths of up to 8.3 m, occur in braided fluvial channel facies of the Searston Formation, a late Pendleian–Arnsbergian (upper Serpukhovian, 326.4–325 Ma) unit. Three morphotypes are present. The first, Pitus primaeva Witham shows exceptionally wide rays (1–8-seriate, rarely to 16-seriate) and tracheids with multiseriate pits. The second, cf. Pitus withamii (Lindley and Hutton) Witham has rather narrower rays (1–3-seriate), and unusually shows ray cells pitted on all walls. Both morphotypes probably represent arborescent pteridosperms. The third, Protopitys scotica Walton is characterized by the occurrence of very short rays (mode: 1 cell high), and represents a putative Progymnosperm. Associated megafloral assemblages are dominated by Diplotmema and Adiantites , which may have comprised the foliage of the lignophytes described herein. However, in marked contrast, palynological assemblages suggest that arborescent lycopsids, sphenopsids and ferns dominated regional vegetation make-up. One resolution to this paradox is the lignophytes may have been growing on levees or well-drained uplands to the south, and washed into the basin in river channels, while pteridophytic vegetation occupied the floodplain. This inference is supported by occurrence of irregular growth interruptions in the fossil woods, suggesting trees grew under a seasonally dry tropical climate.
-
Anatomically-preserved tree-trunks in late Mississippian (Serpukhovian, late Pendleian–Arnsbergian) braided fluvial channel facies, near Searston, southwest Newfoundland, Canada
Review of Palaeobotany and Palynology, 2010Co-Authors: Howard J. Falcon-lang, Jean GaltierAbstract:International audienceLittle is known of the Mississippian palaeobotany of Newfoundland, Canada. Here we improve this situation by describing anatomically-preserved tree-trunks from the Codroy Valley, southwest Newfoundland. The tree-trunks, which have incomplete lengths of up to 8.3 m, occur in braided fluvial channel facies of the Searston Formation, a late Pendleian-Arnsbergian (upper Serpukhovian, 326.4-325 Ma) unit. Three morphotypes are present. The first, Pitus primaeva Witham shows exceptionally wide rays (1-8-seriate, rarely to 16-seriate) and tracheids with multiseriate pits. The second, cf. Pitus withamii (Lindley and Hutton) Witham has rather narrower rays (1-3-seriate), and unusually shows ray cells pitted on all walls. Both morphotypes probably represent arborescent pteridosperms. The third, Protopitys scotica Walton is characterized by the occurrence of very short rays (mode: 1 cell high), and represents a putative Progymnosperm. Associated megafloral assemblages are dominated by Diplotmema and Adiantites, which may have comprised the foliage of the lignophytes described herein. However, in marked contrast, palynological assemblages suggest that arborescent lycopsids, sphenopsids and ferns dominated regional vegetation make-up. One resolution to this paradox is the lignophytes may have been growing on levees or well-drained uplands to the south, and washed into the basin in river channels, while pteridophytic vegetation occupied the floodplain. This inference is supported by occurrence of irregular growth interruptions in the fossil woods, suggesting trees grew under a seasonally dry tropical climat
-
Anatomically-preserved tree-trunks in late Mississippian (Serpukhovian, late Pendleian-Arnsbergian) braided fluvial channel facies, near Searston, southwest Newfoundland, Canada
Review of Palaeobotany and Palynology, 2010Co-Authors: Howard J. Falcon-lang, Jean GaltierAbstract:Little is known of the Mississippian palaeobotany of Newfoundland, Canada. Here we improve this situation by describing anatomically-preserved tree-trunks from the Codroy Valley, southwest Newfoundland. The tree-trunks, which have incomplete lengths of up to 8.3 m, occur in braided fluvial channel facies of the Searston Formation, a late Pendleian-Arnsbergian (upper Serpukhovian, 326.4-325 Ma) unit. Three morphotypes are present. The first, Pitus primaeva Witham shows exceptionally wide rays (1-8-seriate, rarely to 16-seriate) and tracheids with multiseriate pits. The second, cf. Pitus withamii (Lindley and Hutton) Witham has rather narrower rays (1-3-seriate), and unusually shows ray cells pitted on all walls. Both morphotypes probably represent arborescent pteridosperms. The third, Protopitys scotica Walton is characterized by the occurrence of very short rays (mode: 1 cell high), and represents a putative Progymnosperm. Associated megafloral assemblages are dominated by Diplotmema and Adiantites, which may have comprised the foliage of the lignophytes described herein. However, in marked contrast, palynological assemblages suggest that arborescent lycopsids, sphenopsids and ferns dominated regional vegetation make-up. One resolution to this paradox is the lignophytes may have been growing on levees or well-drained uplands to the south, and washed into the basin in river channels, while pteridophytic vegetation occupied the floodplain. This inference is supported by occurrence of irregular growth interruptions in the fossil woods, suggesting trees grew under a seasonally dry tropical climate
