The Experts below are selected from a list of 159 Experts worldwide ranked by ideXlab platform

David M Rudkin - One of the best experts on this subject based on the ideXlab platform.

  • a soft bodied mollusc with radula from the middle cambrian burgess shale
    Nature, 2006
    Co-Authors: Jeanbernard Caron, Amelie H Scheltema, Christoffer Schander, David M Rudkin
    Abstract:

    Odontogriphus omalus was originally described as a problematic non-biomineralized lophophorate organism. Here we re-interpret Odontogriphus based on 189 new specimens including numerous exceptionally well preserved individuals from the Burgess Shale collections of the Royal Ontario Museum. This additional material provides compelling evidence that the feeding apparatus in Odontogriphus is a radula of molluscan architecture comprising two primary bipartite tooth rows attached to a radular membrane and showing replacement by posterior addition. Further characters supporting molluscan affinity include a broad foot bordered by numerous ctenidia located in a mantle groove and a stiffened cuticular dorsum. Odontogriphus has a radula similar to Wiwaxia corrugata but lacks a scleritome. We interpret these animals to be members of an early stem-group mollusc lineage that probably originated in the Neoproterozoic Ediacaran Period, providing support for the retention of a biomat-based grazing community from the late Precambrian Period until at least the Middle Cambrian.

  • A soft-bodied mollusc with radula from the Middle Cambrian Burgess Shale
    Nature, 2006
    Co-Authors: Jeanbernard Caron, Amelie H Scheltema, Christoffer Schander, David M Rudkin
    Abstract:

    Odontogriphus omalus was originally described as a problematic non-biomineralized lophophorate organism. Here we re-interpret Odontogriphus based on 189 new specimens including numerous exceptionally well preserved individuals from the Burgess Shale collections of the Royal Ontario Museum. This additional material provides compelling evidence that the feeding apparatus in Odontogriphus is a radula of molluscan architecture comprising two primary bipartite tooth rows attached to a radular membrane and showing replacement by posterior addition. Further characters supporting molluscan affinity include a broad foot bordered by numerous ctenidia located in a mantle groove and a stiffened cuticular dorsum. Odontogriphus has a radula similar to Wiwaxia corrugata but lacks a scleritome. We interpret these animals to be members of an early stem-group mollusc lineage that probably originated in the Neoproterozoic Ediacaran Period, providing support for the retention of a biomat-based grazing community from the late Precambrian Period until at least the Middle Cambrian. Odontogriphus omalus is a star in the firmament of fossil oddities from the Middle Cambrian Burgess Shales of Canada, looking as it does like a cross between an airbed and a coffee grinder. It also had the added allure of 'problematic' status, as the one original fossil could not be pinned down to any known group of animals. Now, based on a study of 189 new specimens, it emerges as a shell-less mollusc that grazed the algal mats of ancient seafloors. The key to this reinterpretation is the identification of an early form of a feeding device characteristic of molluscs, a radula, a hard rasp-like organism used to strip alga from the rocks. This opens a new window on the earliest history of one of the most important animal groups, and will allow a reassessment of several other enigmatic fossils involved in the origin of multicellular animal life before the Cambrian 'explosion'.

Iñaki Ruiz-trillo - One of the best experts on this subject based on the ideXlab platform.

  • The origin of Metazoa: a unicellular perspective
    Nature Reviews Genetics, 2017
    Co-Authors: Arnau Sebé-pedrós, Bernard M. Degnan, Iñaki Ruiz-trillo
    Abstract:

    The origin of animal multicellularity is one of the major evolutionary transitions in the history of life. The identification and phylogenetic classification of the closest unicellular relatives of animals initiated the study of this transition from a unicellular perspective. Comparative genomics has revealed that many genes associated with animal multicellularity evolved in a unicellular context and has enabled the rich gene repertoire of the unicellular ancestor of animals to be reconstructed. The presence of highly regulated temporal cell types in animal relatives suggests the existence of cell differentiation in the unicellular ancestor of animals. Initial studies suggest important differences between the genome regulatory mechanisms of animals and those of their closest unicellular relatives. These innovations in genome regulation would have been key to the spatial integration of pre-existing cell types at the onset of Metazoa. Multicellular organisms rely on a complex interplay between diverse cell types, but how multicellularity evolved from unicellular ancestors has long been a debated research question. In this Review, the authors describe how comparative and functional genomics have provided valuable insights into the transition between unicellularity and multicellularity, including how various molecular networks have been adopted for multicellular life. The first animals evolved from an unknown single-celled ancestor in the Precambrian Period. Recently, the identification and characterization of the genomic and cellular traits of the protists most closely related to animals have shed light on the origin of animals. Comparisons of animals with these unicellular relatives allow us to reconstruct the first evolutionary steps towards animal multicellularity. Here, we review the results of these investigations and discuss their implications for understanding the earliest stages of animal evolution, including the origin of metazoan genes and genome function.

  • The origin of Metazoa: a unicellular perspective
    Nature reviews. Genetics, 2017
    Co-Authors: Arnau Sebé-pedrós, Bernard M. Degnan, Iñaki Ruiz-trillo
    Abstract:

    The first animals evolved from an unknown single-celled ancestor in the Precambrian Period. Recently, the identification and characterization of the genomic and cellular traits of the protists most closely related to animals have shed light on the origin of animals. Comparisons of animals with these unicellular relatives allow us to reconstruct the first evolutionary steps towards animal multicellularity. Here, we review the results of these investigations and discuss their implications for understanding the earliest stages of animal evolution, including the origin of metazoan genes and genome function.

Jeanbernard Caron - One of the best experts on this subject based on the ideXlab platform.

  • a soft bodied mollusc with radula from the middle cambrian burgess shale
    Nature, 2006
    Co-Authors: Jeanbernard Caron, Amelie H Scheltema, Christoffer Schander, David M Rudkin
    Abstract:

    Odontogriphus omalus was originally described as a problematic non-biomineralized lophophorate organism. Here we re-interpret Odontogriphus based on 189 new specimens including numerous exceptionally well preserved individuals from the Burgess Shale collections of the Royal Ontario Museum. This additional material provides compelling evidence that the feeding apparatus in Odontogriphus is a radula of molluscan architecture comprising two primary bipartite tooth rows attached to a radular membrane and showing replacement by posterior addition. Further characters supporting molluscan affinity include a broad foot bordered by numerous ctenidia located in a mantle groove and a stiffened cuticular dorsum. Odontogriphus has a radula similar to Wiwaxia corrugata but lacks a scleritome. We interpret these animals to be members of an early stem-group mollusc lineage that probably originated in the Neoproterozoic Ediacaran Period, providing support for the retention of a biomat-based grazing community from the late Precambrian Period until at least the Middle Cambrian.

  • A soft-bodied mollusc with radula from the Middle Cambrian Burgess Shale
    Nature, 2006
    Co-Authors: Jeanbernard Caron, Amelie H Scheltema, Christoffer Schander, David M Rudkin
    Abstract:

    Odontogriphus omalus was originally described as a problematic non-biomineralized lophophorate organism. Here we re-interpret Odontogriphus based on 189 new specimens including numerous exceptionally well preserved individuals from the Burgess Shale collections of the Royal Ontario Museum. This additional material provides compelling evidence that the feeding apparatus in Odontogriphus is a radula of molluscan architecture comprising two primary bipartite tooth rows attached to a radular membrane and showing replacement by posterior addition. Further characters supporting molluscan affinity include a broad foot bordered by numerous ctenidia located in a mantle groove and a stiffened cuticular dorsum. Odontogriphus has a radula similar to Wiwaxia corrugata but lacks a scleritome. We interpret these animals to be members of an early stem-group mollusc lineage that probably originated in the Neoproterozoic Ediacaran Period, providing support for the retention of a biomat-based grazing community from the late Precambrian Period until at least the Middle Cambrian. Odontogriphus omalus is a star in the firmament of fossil oddities from the Middle Cambrian Burgess Shales of Canada, looking as it does like a cross between an airbed and a coffee grinder. It also had the added allure of 'problematic' status, as the one original fossil could not be pinned down to any known group of animals. Now, based on a study of 189 new specimens, it emerges as a shell-less mollusc that grazed the algal mats of ancient seafloors. The key to this reinterpretation is the identification of an early form of a feeding device characteristic of molluscs, a radula, a hard rasp-like organism used to strip alga from the rocks. This opens a new window on the earliest history of one of the most important animal groups, and will allow a reassessment of several other enigmatic fossils involved in the origin of multicellular animal life before the Cambrian 'explosion'.

Arnau Sebé-pedrós - One of the best experts on this subject based on the ideXlab platform.

  • The origin of Metazoa: a unicellular perspective
    Nature Reviews Genetics, 2017
    Co-Authors: Arnau Sebé-pedrós, Bernard M. Degnan, Iñaki Ruiz-trillo
    Abstract:

    The origin of animal multicellularity is one of the major evolutionary transitions in the history of life. The identification and phylogenetic classification of the closest unicellular relatives of animals initiated the study of this transition from a unicellular perspective. Comparative genomics has revealed that many genes associated with animal multicellularity evolved in a unicellular context and has enabled the rich gene repertoire of the unicellular ancestor of animals to be reconstructed. The presence of highly regulated temporal cell types in animal relatives suggests the existence of cell differentiation in the unicellular ancestor of animals. Initial studies suggest important differences between the genome regulatory mechanisms of animals and those of their closest unicellular relatives. These innovations in genome regulation would have been key to the spatial integration of pre-existing cell types at the onset of Metazoa. Multicellular organisms rely on a complex interplay between diverse cell types, but how multicellularity evolved from unicellular ancestors has long been a debated research question. In this Review, the authors describe how comparative and functional genomics have provided valuable insights into the transition between unicellularity and multicellularity, including how various molecular networks have been adopted for multicellular life. The first animals evolved from an unknown single-celled ancestor in the Precambrian Period. Recently, the identification and characterization of the genomic and cellular traits of the protists most closely related to animals have shed light on the origin of animals. Comparisons of animals with these unicellular relatives allow us to reconstruct the first evolutionary steps towards animal multicellularity. Here, we review the results of these investigations and discuss their implications for understanding the earliest stages of animal evolution, including the origin of metazoan genes and genome function.

  • The origin of Metazoa: a unicellular perspective
    Nature reviews. Genetics, 2017
    Co-Authors: Arnau Sebé-pedrós, Bernard M. Degnan, Iñaki Ruiz-trillo
    Abstract:

    The first animals evolved from an unknown single-celled ancestor in the Precambrian Period. Recently, the identification and characterization of the genomic and cellular traits of the protists most closely related to animals have shed light on the origin of animals. Comparisons of animals with these unicellular relatives allow us to reconstruct the first evolutionary steps towards animal multicellularity. Here, we review the results of these investigations and discuss their implications for understanding the earliest stages of animal evolution, including the origin of metazoan genes and genome function.

Amelie H Scheltema - One of the best experts on this subject based on the ideXlab platform.

  • a soft bodied mollusc with radula from the middle cambrian burgess shale
    Nature, 2006
    Co-Authors: Jeanbernard Caron, Amelie H Scheltema, Christoffer Schander, David M Rudkin
    Abstract:

    Odontogriphus omalus was originally described as a problematic non-biomineralized lophophorate organism. Here we re-interpret Odontogriphus based on 189 new specimens including numerous exceptionally well preserved individuals from the Burgess Shale collections of the Royal Ontario Museum. This additional material provides compelling evidence that the feeding apparatus in Odontogriphus is a radula of molluscan architecture comprising two primary bipartite tooth rows attached to a radular membrane and showing replacement by posterior addition. Further characters supporting molluscan affinity include a broad foot bordered by numerous ctenidia located in a mantle groove and a stiffened cuticular dorsum. Odontogriphus has a radula similar to Wiwaxia corrugata but lacks a scleritome. We interpret these animals to be members of an early stem-group mollusc lineage that probably originated in the Neoproterozoic Ediacaran Period, providing support for the retention of a biomat-based grazing community from the late Precambrian Period until at least the Middle Cambrian.

  • A soft-bodied mollusc with radula from the Middle Cambrian Burgess Shale
    Nature, 2006
    Co-Authors: Jeanbernard Caron, Amelie H Scheltema, Christoffer Schander, David M Rudkin
    Abstract:

    Odontogriphus omalus was originally described as a problematic non-biomineralized lophophorate organism. Here we re-interpret Odontogriphus based on 189 new specimens including numerous exceptionally well preserved individuals from the Burgess Shale collections of the Royal Ontario Museum. This additional material provides compelling evidence that the feeding apparatus in Odontogriphus is a radula of molluscan architecture comprising two primary bipartite tooth rows attached to a radular membrane and showing replacement by posterior addition. Further characters supporting molluscan affinity include a broad foot bordered by numerous ctenidia located in a mantle groove and a stiffened cuticular dorsum. Odontogriphus has a radula similar to Wiwaxia corrugata but lacks a scleritome. We interpret these animals to be members of an early stem-group mollusc lineage that probably originated in the Neoproterozoic Ediacaran Period, providing support for the retention of a biomat-based grazing community from the late Precambrian Period until at least the Middle Cambrian. Odontogriphus omalus is a star in the firmament of fossil oddities from the Middle Cambrian Burgess Shales of Canada, looking as it does like a cross between an airbed and a coffee grinder. It also had the added allure of 'problematic' status, as the one original fossil could not be pinned down to any known group of animals. Now, based on a study of 189 new specimens, it emerges as a shell-less mollusc that grazed the algal mats of ancient seafloors. The key to this reinterpretation is the identification of an early form of a feeding device characteristic of molluscs, a radula, a hard rasp-like organism used to strip alga from the rocks. This opens a new window on the earliest history of one of the most important animal groups, and will allow a reassessment of several other enigmatic fossils involved in the origin of multicellular animal life before the Cambrian 'explosion'.