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Richard Cloutier - One of the best experts on this subject based on the ideXlab platform.
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Elpistostege and the origin of the vertebrate hand
Nature, 2020Co-Authors: Richard Cloutier, Alice M Clement, Michael S. Y. Lee, Roxanne Noël, Isabelle Béchard, Vincent Roy, John A LongAbstract:The pectoral fin of an Elpistostege watsoni specimen from the Upper Devonian Period of Canada combines digits and fin rays, blurring the line between the appendages of fish and land vertebrates. The evolution of fishes to tetrapods (four-limbed vertebrates) was one of the most important transformations in vertebrate evolution. Hypotheses of tetrapod origins rely heavily on the anatomy of a few tetrapod-like fish fossils from the Middle and Late Devonian Period (393–359 million years ago)^ 1 . These taxa—known as elpistostegalians—include Panderichthys ^ 2 , Elpistostege ^ 3 , 4 and Tiktaalik ^ 1 , 5 , none of which has yet revealed the complete skeletal anatomy of the pectoral fin. Here we report a 1.57-metre-long articulated specimen of Elpistostege watsoni from the Upper Devonian Period of Canada, which represents—to our knowledge—the most complete elpistostegalian yet found. High-energy computed tomography reveals that the skeleton of the pectoral fin has four proximodistal rows of radials (two of which include branched carpals) as well as two distal rows that are organized as digits and putative digits. Despite this skeletal pattern (which represents the most tetrapod-like arrangement of bones found in a pectoral fin to date), the fin retains lepidotrichia (fin rays) distal to the radials. We suggest that the vertebrate hand arose primarily from a skeletal pattern buried within the fairly typical aquatic pectoral fin of elpistostegalians. Elpistostege is potentially the sister taxon of all other tetrapods, and its appendages further blur the line between fish and land vertebrates.
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The Miguasha Fossil-Fish-Lagerstätte: a consequence of the Devonian land–sea interactions
Palaeobiodiversity and Palaeoenvironments, 2011Co-Authors: Richard Cloutier, Jean-noël Proust, Bernadette TessierAbstract:The evolution of vertebrate assemblages in terms of fluctuating environments has rarely been investigated for the Devonian Period. Variation of biodiversity (richness, abundance and species composition) in the diverse Devonian fish assemblage of the Escuminac Formation (Quebec, Canada) is analysed in response to changes in lithofacies, depositional environment and taphonomy through time. Five sequences within an inner wave-dominated estuary show shifts in continentalisation. Although a ubiquitous fish assemblage is identified throughout the formation, species are more diversified and species composition is better structured during relative sea-level rise than during still-stand and relative sea-level fall. Konservat and Konzentrat Fossil- Lagerstatte horizons occur in the transgressive phase of the sequences.
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The Miguasha Fossil-Fish-Lagerstätte: a consequence of the Devonian land-sea interactions
Palaeobiodiversity and Palaeoenvironments, 2011Co-Authors: Richard Cloutier, Jean-noël Proust, Bernadette TessierAbstract:The evolution of vertebrate assemblages in terms of fluctuating environments has rarely been investigated for the Devonian Period. Variation of biodiversity (richness, abundance and species composition) in the diverse Devonian fish assemblage of the Escuminac Formation (Quebec, Canada) is analysed in response to changes in lithofacies, depositional environment and taphonomy through time. Five sequences within an inner wave-dominated estuary show shifts in continentalisation. Although a ubiquitous fish assemblage is identified throughout the formation, species are more diversified and species composition is better structured during relative sea-level rise than during still-stand and relative sea-level fall. Konservat and Konzentrat Fossil- Lagerstätte horizons occur in the transgressive phase of the sequences.
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The oldest articulated chondrichthyan from the Early Devonian Period
Nature, 2003Co-Authors: Randall F. Miller, Richard Cloutier, Susan TurnerAbstract:Chondrichthyans (including living sharks, skates, rays and chimaeras) have a fossil record of scales and dermal denticles perhaps dating back to the Late Ordovician Period, about 455 million years ago^ 1 , 2 . Their fossil tooth record extends to the earliest Devonian Period, almost 418 million years ago^ 3 , whereas the oldest known articulated shark remains date from the Early Devonian Period^ 4 , about 394 million years ago^ 5 . Here we report the discovery of an articulated shark that is almost 409 million years old^ 5 from the Early Devonian (early Emsian) Period of New Brunswick, Canada. The specimen, identified as Doliodus problematicus (Woodward)^ 6 , sheds light on the earliest chondrichthyans and their interrelationships with basal jawed vertebrates. This species has been truly problematic^ 7 . Previously known only from isolated teeth^ 2 , 6 , 8 , it has been identified as an acanthodian and a chondrichthyan. This specimen is the oldest shark showing the tooth families in situ , and preserves one of the oldest chondrichthyan braincases. More notably, it shows the presence of paired pectoral fin-spines, previously unknown in cartilaginous fishes.
Bernadette Tessier - One of the best experts on this subject based on the ideXlab platform.
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The Miguasha Fossil-Fish-Lagerstätte: a consequence of the Devonian land–sea interactions
Palaeobiodiversity and Palaeoenvironments, 2011Co-Authors: Richard Cloutier, Jean-noël Proust, Bernadette TessierAbstract:The evolution of vertebrate assemblages in terms of fluctuating environments has rarely been investigated for the Devonian Period. Variation of biodiversity (richness, abundance and species composition) in the diverse Devonian fish assemblage of the Escuminac Formation (Quebec, Canada) is analysed in response to changes in lithofacies, depositional environment and taphonomy through time. Five sequences within an inner wave-dominated estuary show shifts in continentalisation. Although a ubiquitous fish assemblage is identified throughout the formation, species are more diversified and species composition is better structured during relative sea-level rise than during still-stand and relative sea-level fall. Konservat and Konzentrat Fossil- Lagerstatte horizons occur in the transgressive phase of the sequences.
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The Miguasha Fossil-Fish-Lagerstätte: a consequence of the Devonian land-sea interactions
Palaeobiodiversity and Palaeoenvironments, 2011Co-Authors: Richard Cloutier, Jean-noël Proust, Bernadette TessierAbstract:The evolution of vertebrate assemblages in terms of fluctuating environments has rarely been investigated for the Devonian Period. Variation of biodiversity (richness, abundance and species composition) in the diverse Devonian fish assemblage of the Escuminac Formation (Quebec, Canada) is analysed in response to changes in lithofacies, depositional environment and taphonomy through time. Five sequences within an inner wave-dominated estuary show shifts in continentalisation. Although a ubiquitous fish assemblage is identified throughout the formation, species are more diversified and species composition is better structured during relative sea-level rise than during still-stand and relative sea-level fall. Konservat and Konzentrat Fossil- Lagerstätte horizons occur in the transgressive phase of the sequences.
Kiwamu Minamisawa - One of the best experts on this subject based on the ideXlab platform.
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Plant–Microbe Communications for Symbiosis
Plant and Cell Physiology, 2010Co-Authors: Masayoshi Kawaguchi, Kiwamu MinamisawaAbstract:Symbiosis is a biological phenomenon involving dynamic changes in the genome, metabolism and signaling network, and a multidirectional comprehension of these interactions is required when studying symbiotic organisms. In plant–microbe interactions, two symbiotic systems have been actively studied for many years. One is arbuscular mycorrhizal (AM) symbiosis and the other is root nodule (RN) symbiosis. AM symbiosis is probably the most widespread interaction between plants and microbes, in the context of phylogeny and ecology ( Kistner and Parniske 2002 , Bonfante and Genre 2010 ). More than 80 % of all land plant families are thought to have a symbiotic relationship with AM fungi that belong to the Glomeromycota. The origin of AM symbiosis is thought to be in the early Devonian Period, approximately 400 million years ago. Thus, AM symbiosis is also called the mother of plant root endosymbioses ( Parniske 2008 ). On the other hand, RN symbiosis involves morphogenesis and is formed by communication between plants and nitrogen-fi xing bacteria.
Gavin C. Young - One of the best experts on this subject based on the ideXlab platform.
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placoderms armored fish dominant vertebrates of the Devonian Period
Annual Review of Earth and Planetary Sciences, 2010Co-Authors: Gavin C. YoungAbstract:Placoderms, the most diverse group of Devonian fishes, were globally distributed in all habitable freshwater and marine environments, like teleost fishes in the modern fauna. Their known evolutionary history (Early Silurian–Late Devonian) spanned at least 70 million years. Known diversity (335 genera) will increase when diverse assemblages from new areas are described. Placoderms first occur in the Early Silurian of China, but their diversity remained low until their main evolutionary radiation in the Early Devonian, after which they became the dominant vertebrates of Devonian seas. Most current placoderm data are derived from the second half of the group's evolutionary history, and recent claims that they form a paraphyletic group are based on highly derived Late Devonian forms; 16 shared derived characters are proposed here to support placoderm monophyly. Interrelationships of seven placoderm orders are unresolved because Silurian forms from China are still poorly known. The relationship of placoderms t...
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placoderms armored fish dominant vertebrates of the Devonian Period
Annual Review of Earth and Planetary Sciences, 2010Co-Authors: Gavin C. YoungAbstract:Placoderms, the most diverse group of Devonian fishes, were globally distributed in all habitable freshwater and marine environments, like teleost fishes in the modern fauna. Their known evolutionary history (Early Silurian–Late Devonian) spanned at least 70 million years. Known diversity (335 genera) will increase when diverse assemblages from new areas are described. Placoderms first occur in the Early Silurian of China, but their diversity remained low until their main evolutionary radiation in the Early Devonian, after which they became the dominant vertebrates of Devonian seas. Most current placoderm data are derived from the second half of the group's evolutionary history, and recent claims that they form a paraphyletic group are based on highly derived Late Devonian forms; 16 shared derived characters are proposed here to support placoderm monophyly. Interrelationships of seven placoderm orders are unresolved because Silurian forms from China are still poorly known. The relationship of placoderms t...
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live birth in the Devonian Period
Nature, 2008Co-Authors: Gavin C. Young, John A Long, Kate Trinajstic, Timothy SendenAbstract:The placoderms, now long extinct, were a large and diverse group of fishes, thought to be the most primitive known vertebrates with jaws. Not so primitive, however, that they could not have given birth to live young. A remarkable fossil from the Late Devonian Gogo Formation of Australia, about 380 million years old, represents a new species of placoderm, preserved in the act of giving birth. A single, large embryo is connected to the adult by a mineralized remnant of an umbilical cord. This is the oldest known vertebrate live birth, and reveals reproductive biology comparable to that of some modern sharks and rays. The placoderms were a large and diverse group of distinctive fossil fishes, now thought to be the most primitive known vertebrates with jaws. Placoderm fossils from the Late Devonian Gogo Formation of Australia (about 380 million years ago) show a new species of placoderm, the specimen preserved with a single, large embryo connected to the adult by a mineralized remnant of an umbilical cord. The extinct placoderm fishes were the dominant group of vertebrates throughout the Middle Palaeozoic era1, yet controversy about their relationships within the gnathostomes (jawed vertebrates) is partly due to different interpretations of their reproductive biology2,3,4,5. Here we document the oldest record of a live-bearing vertebrate in a new ptyctodontid placoderm, Materpiscis attenboroughi gen. et sp. nov., from the Late Devonian Gogo Formation of Australia (approximately 380 million years ago)6. The new specimen, remarkably preserved in three dimensions, contains a single, intra-uterine embryo connected by a permineralized umbilical cord. An amorphous crystalline mass near the umbilical cord possibly represents the recrystallized yolk sac. Another ptyctodont from the Gogo Formation, Austroptyctodus gardineri7, also shows three small embryos inside it in the same position. Ptyctodontids have already provided the oldest definite evidence for vertebrate copulation8, and the new specimens confirm that some placoderms had a remarkably advanced reproductive biology, comparable to that of some modern sharks and rays. The new discovery points to internal fertilization and viviparity in vertebrates as originating earliest within placoderms.
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Live birth in the Devonian Period
Nature, 2008Co-Authors: John A Long, Gavin C. Young, Kate Trinajstic, Timothy SendenAbstract:The extinct placoderm fishes were the dominant group of vertebrates throughout the Middle Palaeozoic era, yet controversy about their relationships within the gnathostomes (jawed vertebrates) is partly due to different interpretations of their reproductive biology. Here we document the oldest record of a live-bearing vertebrate in a new ptyctodontid placoderm, Materpiscis attenboroughi gen. et sp. nov., from the Late Devonian Gogo Formation of Australia (approximately 380 million years ago). The new specimen, remarkably preserved in three dimensions, contains a single, intra-uterine embryo connected by a permineralized umbilical cord. An amorphous crystalline mass near the umbilical cord possibly represents the recrystallized yolk sac. Another ptyctodont from the Gogo Formation, Austroptyctodus gardineri, also shows three small embryos inside it in the same position. Ptyctodontids have already provided the oldest definite evidence for vertebrate copulation, and the new specimens confirm that some placoderms had a remarkably advanced reproductive biology, comparable to that of some modern sharks and rays. The new discovery points to internal fertilization and viviparity in vertebrates as originating earliest within placoderms.
John A Long - One of the best experts on this subject based on the ideXlab platform.
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Elpistostege and the origin of the vertebrate hand
Nature, 2020Co-Authors: Richard Cloutier, Alice M Clement, Michael S. Y. Lee, Roxanne Noël, Isabelle Béchard, Vincent Roy, John A LongAbstract:The pectoral fin of an Elpistostege watsoni specimen from the Upper Devonian Period of Canada combines digits and fin rays, blurring the line between the appendages of fish and land vertebrates. The evolution of fishes to tetrapods (four-limbed vertebrates) was one of the most important transformations in vertebrate evolution. Hypotheses of tetrapod origins rely heavily on the anatomy of a few tetrapod-like fish fossils from the Middle and Late Devonian Period (393–359 million years ago)^ 1 . These taxa—known as elpistostegalians—include Panderichthys ^ 2 , Elpistostege ^ 3 , 4 and Tiktaalik ^ 1 , 5 , none of which has yet revealed the complete skeletal anatomy of the pectoral fin. Here we report a 1.57-metre-long articulated specimen of Elpistostege watsoni from the Upper Devonian Period of Canada, which represents—to our knowledge—the most complete elpistostegalian yet found. High-energy computed tomography reveals that the skeleton of the pectoral fin has four proximodistal rows of radials (two of which include branched carpals) as well as two distal rows that are organized as digits and putative digits. Despite this skeletal pattern (which represents the most tetrapod-like arrangement of bones found in a pectoral fin to date), the fin retains lepidotrichia (fin rays) distal to the radials. We suggest that the vertebrate hand arose primarily from a skeletal pattern buried within the fairly typical aquatic pectoral fin of elpistostegalians. Elpistostege is potentially the sister taxon of all other tetrapods, and its appendages further blur the line between fish and land vertebrates.
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live birth in the Devonian Period
Nature, 2008Co-Authors: Gavin C. Young, John A Long, Kate Trinajstic, Timothy SendenAbstract:The placoderms, now long extinct, were a large and diverse group of fishes, thought to be the most primitive known vertebrates with jaws. Not so primitive, however, that they could not have given birth to live young. A remarkable fossil from the Late Devonian Gogo Formation of Australia, about 380 million years old, represents a new species of placoderm, preserved in the act of giving birth. A single, large embryo is connected to the adult by a mineralized remnant of an umbilical cord. This is the oldest known vertebrate live birth, and reveals reproductive biology comparable to that of some modern sharks and rays. The placoderms were a large and diverse group of distinctive fossil fishes, now thought to be the most primitive known vertebrates with jaws. Placoderm fossils from the Late Devonian Gogo Formation of Australia (about 380 million years ago) show a new species of placoderm, the specimen preserved with a single, large embryo connected to the adult by a mineralized remnant of an umbilical cord. The extinct placoderm fishes were the dominant group of vertebrates throughout the Middle Palaeozoic era1, yet controversy about their relationships within the gnathostomes (jawed vertebrates) is partly due to different interpretations of their reproductive biology2,3,4,5. Here we document the oldest record of a live-bearing vertebrate in a new ptyctodontid placoderm, Materpiscis attenboroughi gen. et sp. nov., from the Late Devonian Gogo Formation of Australia (approximately 380 million years ago)6. The new specimen, remarkably preserved in three dimensions, contains a single, intra-uterine embryo connected by a permineralized umbilical cord. An amorphous crystalline mass near the umbilical cord possibly represents the recrystallized yolk sac. Another ptyctodont from the Gogo Formation, Austroptyctodus gardineri7, also shows three small embryos inside it in the same position. Ptyctodontids have already provided the oldest definite evidence for vertebrate copulation8, and the new specimens confirm that some placoderms had a remarkably advanced reproductive biology, comparable to that of some modern sharks and rays. The new discovery points to internal fertilization and viviparity in vertebrates as originating earliest within placoderms.
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Live birth in the Devonian Period
Nature, 2008Co-Authors: John A Long, Gavin C. Young, Kate Trinajstic, Timothy SendenAbstract:The extinct placoderm fishes were the dominant group of vertebrates throughout the Middle Palaeozoic era, yet controversy about their relationships within the gnathostomes (jawed vertebrates) is partly due to different interpretations of their reproductive biology. Here we document the oldest record of a live-bearing vertebrate in a new ptyctodontid placoderm, Materpiscis attenboroughi gen. et sp. nov., from the Late Devonian Gogo Formation of Australia (approximately 380 million years ago). The new specimen, remarkably preserved in three dimensions, contains a single, intra-uterine embryo connected by a permineralized umbilical cord. An amorphous crystalline mass near the umbilical cord possibly represents the recrystallized yolk sac. Another ptyctodont from the Gogo Formation, Austroptyctodus gardineri, also shows three small embryos inside it in the same position. Ptyctodontids have already provided the oldest definite evidence for vertebrate copulation, and the new specimens confirm that some placoderms had a remarkably advanced reproductive biology, comparable to that of some modern sharks and rays. The new discovery points to internal fertilization and viviparity in vertebrates as originating earliest within placoderms.