Leis' conundrum: Homology of the clavus of the ocean sunfishes. 1. Ontogeny of the median fins and axial skeleton of <i>Monotrete leiurus</i> (Teleostei, Tetraodontiformes, Tetraodontidae)

Britz, Ralf; Johnson, G. David

doi:10.1002/jmor.10243

Cited by 17 publications

(20 citation statements)

References 19 publications

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“…Another unusual feature of Ranzania is the sharp angle between the occiput and the anterior vertebrae, which only straightens gradually during further development. A similar, though less pronounced, curvature is also present during the development of the axial skeleton of Monotrete (Britz and Johnson, 2004) and may occur in a number of other tetraodontiforms.…”

Section: Ontogeny Of Axial Skeletonmentioning

confidence: 65%

“…The whole arrangement thus strongly resembles that of the first anal-fin pterygiophore of Monotrete leiurus (see Part 1, Britz and Johnson, 2004: fig. 1).…”

Section: Ranzania Laevis 21 MMmentioning

confidence: 67%

“…A striking early developmental character that distinguishes Ranzania from the closely related Monotrete (see Part 1, Britz and Johnson, 2004) is the lack of the flexion of the chorda, first pointed out by Leis (1977). Another unusual feature of Ranzania is the sharp angle between the occiput and the anterior vertebrae, which only straightens gradually during further development.…”

Section: Ontogeny Of Axial Skeletonmentioning

confidence: 98%

“…All neural and hemal arches and spines of the vertebral column of Ranzania develop in membrane bone, as described for most of these elements in the tetraodontid Monotrete (Britz and Johnson, 2004). It is unclear at present if the lack of cartilaginously preformed elements of the vertebral column is a more widespread condition among tetraodontiforms.…”

Section: Ontogeny Of Axial Skeletonmentioning

confidence: 99%

“…The goal of this article is to review the problem of homology of the clavus of molids from an ontogenetic perspective. In Part 1 (Britz and Johnson, 2004) we described the ontogeny of the axial skeleton and the dorsal, anal, and caudal fins and supporting structures in Monotrete leiurus, a member of the less modified family Tetraodontidae, belonging to the putative sister group of the Molidae. In this second part we provide an account of the ontogeny of the axial skeleton and median fins and their supports in the molid Ranzania laevis and compare it with that of the tetraodontid M. leiurus to elucidate relative modification of various elements.…”

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confidence: 99%

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Leis' conundrum: Homology of the clavus of the ocean sunfishes. 2. Ontogeny of the median fins and axial skeleton of Ranzania laevis (Teleostei, Tetraodontiformes, Molidae)

Johnson

Britz

2004

Journal of Morphology

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One of the most conspicuous characters of the ocean sunfishes, family Molidae, is the punctuation of the body by a deep, abbreviated, caudal fin-like structure extending vertically between the posterior ends of the dorsal and anal fins, termed the clavus by Fraser Brunner. Homology of the clavus has been a matter of debate since the first studies on molid anatomy in the early 1800s. Two hypotheses have been proposed: 1) It is a highly modified caudal fin; 2) It is formed by highly modified elements of the dorsal and anal fins. To resolve this homology issue, we studied the ontogeny of the molid vertebral column and median fins and compared it to that of a less morphologically derived gymnodont (see Part 1 of this study), a member of the family Tetraodontidae. We show that in molids the chorda never flexes during development, that the claval rays form from the posterior ends of the dorsal and anal fins toward the middle, thus closing the gap inward, and that elements of the molid clavus have an identical development and composition as the proximal-middle and distal radials of the regular dorsal and anal fins. We thus conclude that the molid clavus is unequivocally formed by modified elements of the dorsal and anal fin and that the caudal fin is lost in molids.

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Section: Ontogeny Of Axial Skeletonmentioning

confidence: 65%

“…The whole arrangement thus strongly resembles that of the first anal-fin pterygiophore of Monotrete leiurus (see Part 1, Britz and Johnson, 2004: fig. 1).…”

Section: Ranzania Laevis 21 MMmentioning

confidence: 67%

Section: Ontogeny Of Axial Skeletonmentioning

confidence: 98%

Section: Ontogeny Of Axial Skeletonmentioning

confidence: 99%

mentioning

confidence: 99%

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Leis' conundrum: Homology of the clavus of the ocean sunfishes. 2. Ontogeny of the median fins and axial skeleton of Ranzania laevis (Teleostei, Tetraodontiformes, Molidae)

Johnson

Britz

2004

Journal of Morphology

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Ontogeny and homology of the claustra in Otophysan Ostariophysi (Teleostei)

Britz

Hoffmann

2006

J. Morphol.

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We studied the ontogeny of the claustrum comparatively in representatives of all otophysan subgroups. The claustrum of cypriniforms has a cartilaginous precursor, the claustral cartilage, which subsequently ossifies perichondrally at its anterior face and develops an extensive lamina of membrane bone. The membrane bone component of the claustrum and its close association with the atrium sinus imparis, a perilymphatic space of the Weberian apparatus, are both synapomorphies of cypriniforms. The characiform claustrum is not preformed in cartilage and originates as a membrane bone ossification, a putative synapomorphy of that taxon. Among siluriforms, the claustrum is present only in more basal groups and originates as an elongate cartilage that ossifies in a characteristic ventrodorsal direction, possibly a synapomorphy of catfishes. Gymnotiforms lack the claustral cartilage and claustrum. We review all previous hypothesis of claustrum homology in light of the above findings and conclude that the most plausible hypothesis is the one originally proposed by Bloch ([1900] Jen Z Naturw 34:1-64) that claustra are homologs of the supradorsals of the first vertebra.

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Ontogeny, variation, and homology in Salvelinus alpinus caudal skeleton (Teleostei: Salmonidae)

Grünbaum

Cloutier

2009

Journal of Morphology

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The ontogeny of the caudal skeleton in the Arctic charr, Salvelinus alpinus was examined using an extensive series of cleared and stained specimens. We demonstrate the presence of skeletal components never reported previously within the Salmonidae. In contrast to the generalized condition for salmonids, seven hypurals (instead of six), and four uroneurals (instead of three) have been found in some specimens. Variation in the number and condition of epurals is documented. New hypotheses are proposed concerning (1) relationships among centra and their associated elements, (2) phylogenetic distribution of caudal characters within the Salmonidae, and (3) homology of caudal components. Using the published phylogenetic hypotheses, we provide evidence, that a seventh hypural and a fourth uroneural are taxic atavism in salmonids. The development of the salmonid homocercal fin is discussed in the light of a polyural scheme based on evidences of a one-to-one relationship among ural centra and their associated elements.

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Leis' conundrum: Homology of the clavus of the ocean sunfishes. 1. Ontogeny of the median fins and axial skeleton of Monotrete leiurus (Teleostei, Tetraodontiformes, Tetraodontidae)

Cited by 17 publications

References 19 publications

Leis' conundrum: Homology of the clavus of the ocean sunfishes. 2. Ontogeny of the median fins and axial skeleton of Ranzania laevis (Teleostei, Tetraodontiformes, Molidae)

Leis' conundrum: Homology of the clavus of the ocean sunfishes. 2. Ontogeny of the median fins and axial skeleton of Ranzania laevis (Teleostei, Tetraodontiformes, Molidae)

Ontogeny and homology of the claustra in Otophysan Ostariophysi (Teleostei)

Ontogeny, variation, and homology in Salvelinus alpinus caudal skeleton (Teleostei: Salmonidae)

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