Calcification of early vertebrate cartilage

Janvier, Philippe; Arsenault, Marius

doi:10.1038/417609a

Cited by 38 publications

(23 citation statements)

References 4 publications

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“…First, the presence of mineralized endoskeletal tissues, including both calcified cartilage and perichondral bone, in placoderms, is consistent with present understanding of vertebrate phylogeny (Donoghue and Sansom, 2002; Wang et al, 2005;Donoghue et al, 2006). Mineralized endoskeletal tissues have been reported in Petromyzontidae (Bardack and Zangerl, 1971;Langille and Hall, 1993), Astraspida (Ørvig, 1951;Denison, 1967;Sansom et al, 1997), Anaspida (Janvier and Arsenault, 2002), Arandaspida (Gagnier, 1993), Galeaspida (Janvier, 1984(Janvier, , 1990Wang, 1991;Wang et al, 2005;Zhu and Janvier, 1998), Pituriaspida (Young, 1991), Osteostraci (Stensiö, 1927;Denison, 1947Denison, , 1951Wä ngsjö, 1952;Ørvig, 1957a;Gross, 1961) and Placodermi (Ørvig, 1951). The fusion of endoskeletal tissues to the internal surface of external dermal skeletal elements has previously been reported in the stem gnathostome clades Osteostraci (Stensiö, 1927;Denison, 1947Denison, , 1951Wä ngsjö, 1952;Ørvig, 1957a;Gross, 1961) and Galeaspida (Janvier, 1984;1990;Wang, 1991;Wang et al, 2005;Zhu and Janvier, 1998).…”

Section: Discussion Tissue Homologiessupporting

confidence: 54%

Skeletal histology of Bothriolepis canadensis (Placodermi, Antiarchi) and evolution of the skeleton at the origin of jawed vertebrates

Downs

Donoghue

2009

Journal of Morphology

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We used light microscopy and scanning electron microscopy to compile a complete histological description of the dermal skeleton of the antiarch placoderm, Bothriolepis canadensis. Placodermi is most often cited as the sister group of crown group Gnathostomata, but some recent authors propose that placoderms instead represent a paraphyly of forms leading to the crown. In either phylogenetic scenario, comparative analysis of placoderm and gnathostome histological data allows us to address the primitive condition of both the gnathostome skeleton and the jawed vertebrate skeleton. The results of this work support the interpretation that the external skeleton of Bothriolepis canadensis is comprised exclusively of cellular dermal bone tissue. The unique stratification of the antiarch thoracic skeleton that has led to controversial interpretations in the past is explained by the nature of the articulations between adjacent elements. Skeletal features long thought to be gnathostome innovations are instead discovered to arise along the gnathostome stem. These innovations include secondary osteons, the systematic reconstruction of the skeleton in response to growth, and unfused, overlapping joints that enable marginal growth while maximizing the area of the articulation surface. The extensive evidence for spheritic mineralization agrees with a model of the skeleton as one capable of a high growth rate and active remodeling. Dermal skeletal development in both placoderms and osteichthyans is primarily skeletogenetic with only a minor odontogenetic contribution in some taxa. This demonstrates the problem inherent with assuming a broad application for those hypotheses of dermal skeletal evolution that are based on a chondrichthyan model. Our results highlight the importance of anatomical and ontogenetic context in the interpretation of fossil tissues.

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Section: Discussion Tissue Homologiessupporting

confidence: 54%

Skeletal histology of Bothriolepis canadensis (Placodermi, Antiarchi) and evolution of the skeleton at the origin of jawed vertebrates

Downs

Donoghue

2009

Journal of Morphology

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“…Furthermore, the ancient agnathan Euphanerops shows mineralized vertebral elements, and among these might be morphologically distinguishable dorsal and ventral vertebral arch elements (Janvier and Arsenault, 2002). Their distribution is clearly periodic along the axis, resembling the lamprey dorsal arch elements (Janvier, 2007;Janvier and Arsenault, 2002). The phylogenetic position of Euphanerops is not clear, but it could represent a stem cyclostome (Janvier, 2011).…”

Section: Vertebral Arches Might Have Evolved First In the Ancestral Cmentioning

confidence: 99%

“…The mostly softbodied fossil Haikouichthys, described as a stem craniate, has elements positioned along its notochord that might represent vertebral rudiments (Shu et al, 2003). Furthermore, the ancient agnathan Euphanerops shows mineralized vertebral elements, and among these might be morphologically distinguishable dorsal and ventral vertebral arch elements (Janvier and Arsenault, 2002). Their distribution is clearly periodic along the axis, resembling the lamprey dorsal arch elements (Janvier, 2007;Janvier and Arsenault, 2002).…”

Section: Vertebral Arches Might Have Evolved First In the Ancestral Cmentioning

confidence: 99%

Building the backbone: the development and evolution of vertebral patterning

et al. 2015

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The segmented vertebral column comprises a repeat series of vertebrae, each consisting of two key components: the vertebral body (or centrum) and the vertebral arches. Despite being a defining feature of the vertebrates, much remains to be understood about vertebral development and evolution. Particular controversy surrounds whether vertebral component structures are homologous across vertebrates, how somite and vertebral patterning are connected, and the developmental origin of vertebral bone-mineralizing cells. Here, we assemble evidence from ichthyologists, palaeontologists and developmental biologists to consider these issues. Vertebral arch elements were present in early stem vertebrates, whereas centra arose later. We argue that centra are homologous among jawed vertebrates, and review evidence in teleosts that the notochord plays an instructive role in segmental patterning, alongside the somites, and contributes to mineralization. By clarifying the evolutionary relationship between centra and arches, and their varying modes of skeletal mineralization, we can better appreciate the detailed mechanisms that regulate and diversify vertebral patterning.

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“…Endoskeletal mineralization is widely distributed amongst vertebrates, including jawed forms (Donoghue et al, 2006) and several jawless groups: Eriptychius (Denison, 1967;Smith & Hall, 1990), Euphanerops (Janvier & Arsenault, 2002), osteostracans (Janvier, 1985a, b), galeaspids (Halstead, 1979;Zhu & Janvier, 1998, Wang et al, 2005, and quite possibly pituriaspids (Young, 1991). Extensive mineralization of the braincase is, however, limited to the latter three agnathan groups plus jawed vertebrates.…”

Section: Primary Skeletonmentioning

confidence: 99%

The characters of Palaeozoic jawed vertebrates

2014

Zoological Journal of the Linnean Society

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Newly discovered fossils from the Silurian and Devonian periods are beginning to challenge embedded perceptions about the origin and early diversification of jawed vertebrates (gnathostomes). Nevertheless, an explicit cladistic framework for the relationships of these fossils relative to the principal crown lineages of the jawed vertebrates (osteichthyans: bony fishes and tetrapods; chondrichthyans: sharks, batoids, and chimaeras) remains elusive. We critically review the systematics and character distributions of early gnathostomes and provide a clearly stated hierarchy of synapomorphies covering the jaw-bearing stem gnathostomes and osteichthyan and chondrichthyan stem groups. We show that character lists, designed to support the monophyly of putative groups, tend to overstate their strength and lack cladistic corroboration. By contrast, synapomorphic hierarchies are more open to refutation and must explicitly confront conflicting evidence. Our proposed synapomorphy scheme is used to evaluate the status of the problematic fossil groups Acanthodii and Placodermi, and suggest profitable avenues for future research. We interpret placoderms as a paraphyletic array of stem-group gnathostomes, and suggest what we regard as two equally plausible placements of acanthodians: exclusively on the chondrichthyan stem, or distributed on both the chondrichthyan and osteichthyan stems.

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Calcification of early vertebrate cartilage

Cited by 38 publications

References 4 publications

Skeletal histology of Bothriolepis canadensis (Placodermi, Antiarchi) and evolution of the skeleton at the origin of jawed vertebrates

Skeletal histology of Bothriolepis canadensis (Placodermi, Antiarchi) and evolution of the skeleton at the origin of jawed vertebrates

Building the backbone: the development and evolution of vertebral patterning

The characters of Palaeozoic jawed vertebrates

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