Calcified cartilage in the paired fins of the osteostracan<i>Escuminaspis laticeps</i>(Traquair 1880), from the Late Devonian of Miguasha (Québec, Canada), with a consideration of the early evolution of the pectoral fin endoskeleton in vertebrates

Janvier, Philippe; Arsenault, Marius; Desbiens, Sylvain

doi:10.1671/0272-4634(2004)024[0773:ccitpf]2.0.co;2

Cited by 48 publications

(30 citation statements)

References 16 publications

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“…For example, the earliest pectoral appendage is found in osteostracans, in which the endochondral fin proper was articulated to the dermal plates circumscribing the branchial arches via an endochondral girdle (Janvier, , ; Coates, ; Janvier et al. ). Although the homology between each dermal plate and each dermal girdle is yet to be unveiled (McGonnell, ), if the dermal girdle in amniotes represents the caudal wall of the branchial chamber, the endochondral pectoral appendage would have always been associated with the branchial wall since its appearance in evolution.…”

Section: Discussionmentioning

confidence: 99%

Developmental origin of the clavicle, and its implications for the evolution of the neck and the paired appendages in vertebrates

et al. 2016

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In fish, the pectoral appendage is adjacent to the head, but during vertebrate evolution a long neck region emerged via caudal relocation of the pectoral appendage. The pectoral appendage is comprised of endochondral portions, such as the humerus and the scapula, and a dermal portion, such as the clavicle, that contributes to the shoulder girdle. In the search for clues to the mechanism of the caudal relocation of the pectoral appendage, the cell lineage of the rostral lateral plate mesoderm was analyzed in chickens. It was found that, despite the long neck region in chickens, the origin of the clavicle attached to the head mesoderm ranged between 1 and 14 somite levels. Because the pectoral limb bud and the endochondral pectoral appendage developed on 15-20 and 15-24 somite levels, respectively, the clavicle-forming region corresponds to the embryonic neck, which suggests that the relocation would have been executed by the expansion of the source of the clavicle. The rostral portion of the clavicle-forming region overlaps the source of the cucullaris muscle, embraces the pharyngeal arches caudally, and can be experimentally replaced with the head mesoderm to form the cucullaris muscle, which implies that the mesodermal portion could have been the head mesoderm and that the clavicle would have developed at the head/trunk boundary. The link between the head mesoderm and the presumptive clavicle appears to have been the developmental constraint needed to create the evolutionarily conserved musculoskeletal connectivities characterizing the gnathostome neck. In this sense, the dermal girdle of the ganathostomes would represent the wall of the branchial chamber into which the endochondral pectoral appendage appears to have attached since its appearance in evolution.

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Section: Discussionmentioning

confidence: 99%

Developmental origin of the clavicle, and its implications for the evolution of the neck and the paired appendages in vertebrates

et al. 2016

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“…Watson (1954) acknowledged the fin-like nature of these structures but considered that they were neomorphs and not homologous to the pectoral fins of gnathostomes. Osteostracan paired fins are anteriorly positioned, there are traces of muscular attachments and foramens for the passage of nerves and blood vessels (Janvier, 1978(Janvier, , 1996bJohanson, 2002), and there are endoskeletal supports (Janvier, 1996b;Janvier & Arsenault, 1996;Janvier, Arsenault, et al, 2004). Osteostracan paired fins are anteriorly positioned, there are traces of muscular attachments and foramens for the passage of nerves and blood vessels (Janvier, 1978(Janvier, , 1996bJohanson, 2002), and there are endoskeletal supports (Janvier, 1996b;Janvier & Arsenault, 1996;Janvier, Arsenault, et al, 2004).…”

Section: 'Cephalaspidomorphi'mentioning

confidence: 99%

A critical appraisal of appendage disparity and homology in fishes

2019

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Fishes are both extremely diverse and morphologically disparate. Part of this disparity can be observed in the numerous possible fin configurations that may differ in terms of the number of fins as well as fin shapes, sizes and relative positions on the body. Here, we thoroughly review the major patterns of disparity in fin configurations for each major group of fishes and discuss how median and paired fin homologies have been interpreted over time. When taking into account the entire span of fish diversity, including both extant and fossil taxa, the disparity in fin morphologies greatly complicates inferring homologies for individual fins. Given the phylogenetic scope of this review, structural and topological criteria appear to be the most useful indicators of fin identity. We further suggest that it may be advantageous to consider some of these fin homologies as nested within the larger framework of homologous fin‐forming morphogenetic fields. We also discuss scenarios of appendage evolution and suggest that modularity may have played a key role in appendage disparification. Fin modules re‐expressed within the boundaries of fin‐forming fields could explain how some fins may have evolved numerous times independently in separate lineages (e.g., adipose fin), or how new fins may have evolved over time (e.g., anterior and posterior dorsal fins, pectoral and pelvic fins). We favour an evolutionary scenario whereby median appendages appeared from a unique field of competence first positioned throughout the dorsal and ventral midlines, which was then redeployed laterally leading to paired appendages.

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“…Osteostraci (Wenlock—Frasnian) are the closest jawless relatives of jawed vertebrates, sharing with crown gnathostomes, to the exclusion of other ‘ostracoderms’, sclerotic rings, an ossified sclera, paired pectoral fins with an internal skeletal support, cellular bone, and ossification of the braincase with perichondral bone (Janvier, , , ). Osteostracans therefore represent an important grade in the evolution of the vertebrate skeleton, but despite being well‐studied, their dermal skeletal histology is poorly understood within an evolutionary context and conflicting interpretations of their tissue homologies remain (e.g., Sire et al, ).…”

Section: Introductionmentioning

confidence: 99%

The dermal skeleton of the jawless vertebrateTremataspis mammillata(Osteostraci, stem‐Gnathostomata)

O'Shea

Keating

Donoghue

2019

Journal of Morphology

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Osteostracans are the closest jawless relatives of jawed vertebrates, informing the gradual assembly of the vertebrate mineralised skeleton. Conflicting interpretations of their dermal skeletal histology arise from failure to account for topological variation, obscuring their significance in elucidating vertebrate skeletal evolution. To resolve this, we characterize the cranial and trunk dermal skeleton of a single individual of Tremataspis mammillata (Osteostraci, Thyestiida) at submicron resolution using synchrotron‐ and computed‐ tomography. Our results show that the architecture of the Tremataspis dermal skeleton is, for the most part, conserved over the skeleton and is broadly consistent with previous histological hypotheses based on 2D thin section study. We resolve debate over the homology of the basal layer, identifying it as osteogenic acellular isopedin rather than odontogenic elasmodine or metaplastic ossification of the stratum compactum of the dermis. We find topological variation between all dermal skeletal elements studied, and particularly between the cranial and postcranial dermal skeleton. This variation can be largely explained by reduction in differentiation due to geometric constraints imposed within smaller skeletal elements, such as scales. Our description of the dermal skeleton of Tremataspis mammillata provides a foundation for interpreting data from cursory topological samples of dermal skeletal diversity obtained in other osteostracans. This reveals general aspects of histological structure that must be ancestral for osteostracans and, likely, ancestral jawed vertebrates. Finally, we draw the distinction between hypotheses and descriptions in palaeohistology.

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Calcified cartilage in the paired fins of the osteostracanEscuminaspis laticeps(Traquair 1880), from the Late Devonian of Miguasha (Québec, Canada), with a consideration of the early evolution of the pectoral fin endoskeleton in vertebrates

Cited by 48 publications

References 16 publications

Developmental origin of the clavicle, and its implications for the evolution of the neck and the paired appendages in vertebrates

Developmental origin of the clavicle, and its implications for the evolution of the neck and the paired appendages in vertebrates

A critical appraisal of appendage disparity and homology in fishes

The dermal skeleton of the jawless vertebrateTremataspis mammillata(Osteostraci, stem‐Gnathostomata)

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