Pectoral fins of rhizodontids and the evolution of pectoral appendages in the tetrapod stem-group

Jeffery, Jonathan E.

doi:10.1111/j.1095-8312.2001.tb01388.x

Cited by 26 publications

(30 citation statements)

References 48 publications

(76 reference statements)

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“…In Barameda, this depression has striations interpreted as muscle attachment scars (Garvey et al, 2005). Jeffery (2001) also suggested that the deltoid and supinator processes identified by Long (1989) in Barameda may be part of a continuous dorsal ridge, as in Rhizodus, and Garvey et al (2005) do not disagree with this position, noting that continuous ridges are present in Aztecia and Sauripterus, although their orientation is somewhat different. In Gogonasus, Holland (2013) described a deltoid process that was 'rounded, moderate in size, and is marked with scars for muscle attachment' and, distally, a 'large supinator process, which is pointed and marked with a small circular area of unfinished bone' (p. 156).…”

Section: (B) Tetrapodomorph Fishmentioning

confidence: 99%

“…Therefore, Panderichthys and Tiktaalik are interpreted as lacking a pectoral process, while that of the Catskill humerus is weakly developed, a position followed by Ahlberg (2011). This means that the 'pectoralis process' in Rhizodus, Strepsodus (Andrews & Westoll, 1970b;Jeffery, 2001) (black arrow, Fig. 9D), Sauripterus (Davis et al, 2004) and Sterropterygion (Rackoff, 1980), located at the preaxial end of the ventral humeral ridge, was probably misidentified (i.e.…”

Section: (B) Tetrapodomorph Fishmentioning

confidence: 99%

“…Vorobyeva (2000) also describes a latissimus dorsi process in these two taxa. However, Jeffery (2001), who examined additional specimens, contended that neither fish has a latissimus dorsi process. In Strepsodus, the two structures previously identified as possible latissimus dorsi processes are, according to Jeffery (2001), either part of the ventral humeral ridge or result from damage to the specimen (white and black arrows in Fig.…”

Section: (B) Tetrapodomorph Fishmentioning

confidence: 99%

“…Vorobyeva (2000) identified a separate 'supinator attachment' process in Rhizodus in a different location: distal to the dorsal ridge. Jeffery (2001) re-examined the specimens, including a second, more-complete specimen of Rhizodus (NMS G 1972.434c), and concluded that the processes that make up the dorsal ridge are not clearly differentiated and that the 'supinator attachment' of Vorobyeva (2000) in Strepsodus (grey arrow, Fig. 9C) is an artefact of crushing damage to the dorsal ridge.…”

Section: (B) Tetrapodomorph Fishmentioning

confidence: 99%

“…The ventral process (or 'postaxial process') in lobe-finned fish is thought to be homologous with the entepicondyle and ventral humeral ridge of tetrapods, and its presence is considered to be a sarcopterygian synapomorphy (Andrews & Westoll, 1970a;Ahlberg, 1989;Jeffery, 2001;Friedman et al, 2007). In tetrapodomorph fish such as Strepsodus, Sauripterus, Gogonasus, and Eusthenopteron, the entepicondyle is continuous with the ventral humeral ridge ('oblique ventral ridge'), part of which forms the pectoralis insertion (hr, Fig.…”

Section: (2) Humerusmentioning

confidence: 99%

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Reconstructing pectoral appendicular muscle anatomy in fossil fish and tetrapods over the fins‐to‐limbs transition

et al. 2017

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The question of how tetrapod limbs evolved from fins is one of the great puzzles of evolutionary biology. While palaeontologists, developmental biologists, and geneticists have made great strides in explaining the origin and early evolution of limb skeletal structures, that of the muscles remains largely unknown. The main reason is the lack of consensus about appendicular muscle homology between the closest living relatives of early tetrapods: lobe-finned fish and crown tetrapods. In the light of a recent study of these homologies, we re-examined osteological correlates of muscle attachment in the pectoral girdle, humerus, radius, and ulna of early tetrapods and their close relatives. Twenty-nine extinct and six extant sarcopterygians were included in a meta-analysis using information from the literature and from original specimens, when possible. We analysed these osteological correlates using parsimony-based character optimization in order to reconstruct muscle anatomy in ancestral lobe-finned fish, tetrapodomorph fish, stem tetrapods, and crown tetrapods. Our synthesis revealed that many tetrapod shoulder muscles probably were already present in tetrapodomorph fish, while most of the more-distal appendicular muscles either arose later from largely undifferentiated dorsal and ventral muscle masses or did not leave clear correlates of attachment in these taxa. Based on this review and meta-analysis, we postulate a stepwise sequence of specific appendicular muscle acquisitions, splits, and fusions that led from the ancestral sarcopterygian pectoral fin to the ancestral tetrapod forelimb. This sequence largely agrees with previous hypotheses based on palaeontological and comparative work, but it is much more comprehensive in terms of both muscles and taxa. Combined with existing information about the skeletal system, our new synthesis helps to illuminate the genetic, developmental, morphological, functional, and ecological changes that were key components of the fins-to-limbs transition.

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Section: (B) Tetrapodomorph Fishmentioning

confidence: 99%

Section: (B) Tetrapodomorph Fishmentioning

confidence: 99%

Section: (B) Tetrapodomorph Fishmentioning

confidence: 99%

Section: (B) Tetrapodomorph Fishmentioning

confidence: 99%

Section: (2) Humerusmentioning

confidence: 99%

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Reconstructing pectoral appendicular muscle anatomy in fossil fish and tetrapods over the fins‐to‐limbs transition

et al. 2017

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Pectoral girdle and fin anatomy ofGogonasus andrewsaelong, 1985: Implications for tetrapodomorph limb evolution

Holland

2012

Journal of Morphology

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Recently discovered material has yielded new information on the pectoral girdle and fin endoskeleton of Gogonasusandrewsae (Frasnian Gogo Formation, Kimberley Region, Western Australia). These elements permit the first comprehensive description of the anocleithrum, cleithrum, scapulocoracoid, and lepidotrichia. New autapomorphies of Gogonasus include a square exposed region on the supracleithrum, an unusual knob-like process on the scapulocoracoid, a relatively small entepicondyle, and lepidotrichia with I-beam-shaped cross sections. Several poorly ossified regions on the scapulocoracoid and humerus indicate an early ontogenetic state, as with other immature tetrapodomorph fish specimens. A phylogenetic analysis indicates a more stemward position for Gogonasus in a weakly supported clade with other "osteolepidid" taxa, compared to other recent studies placing Gogonasus crownward of osteolepidid fishes and the Tristichopteridae, as the sister taxon to the "Elpistosteglia" + Tetrapoda. A phylogenetic position among megalichthyid fishes is suggested for Sterropterygion, while radiographs of the megalichthyid Cladarosymblema show a scythe-like radius terminating distally with that of the intermedium. New data on the scapulocoracoid of the rhizodontid Barameda reveals a coroacoid crest and small supraglenoid foramen.

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The functional morphology of the pectoral fin girdle of the Spiny Dogfish (Squalus acanthias): Implications for the evolutionary history of the pectoral girdle of vertebrates

Gudo

Homberger

2002

Senckenbergiana lethaea

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Fresh functional-morphological observations and theoretical considerations warrant a re-analysis of the traditional assumptions that the head skeleton of sharks consists of the chondrocranium and visceral arches and that the pectoral fin girdle is part of the appendicular skeleton. The scapulocoracoid cartilage of the Spiny Dogfish (Squalus acanthias) plays at least three major roles: (1) Asa mechanical separator between the lateral undulations of the trunk and the vertical movements of the visceral arches; (2) asa structural basis for the anchoring of the pectoral fins: and (3) as the place of origin of the cucullaris and hypobranchial muscles which not only open the jaws and expand the branchial basket, but at the same time also affect the contractions of the heart and the timing of blood flow through the gills. Hence, the scapulocoracoid cartilage is an integral part of the head. It most likely evolve d in connection with the evolution of the jaw apparatus and not simply as a part of the appendicular skeleton. Furthermore, the head is a mechanically coherent system, in which the central alimentary, circulatory, respiratory and nervous systems of the organism converge. These central feeding, respiratory and circulatory functions are not simply choreographed by the central nervous system, but are concatenated by the mechanical construction of the head itself. Sueh a conceptualization of the selachian head raises fresh questions concerning the constraints and potentialities of the evolutionary transformations of the various components of the head and pectoral appendages during the transition from aquatic pisciform to terrestrial tetrapod vertebrates.

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Pectoral fins of rhizodontids and the evolution of pectoral appendages in the tetrapod stem-group

Cited by 26 publications

References 48 publications

Reconstructing pectoral appendicular muscle anatomy in fossil fish and tetrapods over the fins‐to‐limbs transition

Reconstructing pectoral appendicular muscle anatomy in fossil fish and tetrapods over the fins‐to‐limbs transition

Pectoral girdle and fin anatomy ofGogonasus andrewsaelong, 1985: Implications for tetrapodomorph limb evolution

The functional morphology of the pectoral fin girdle of the Spiny Dogfish (Squalus acanthias): Implications for the evolutionary history of the pectoral girdle of vertebrates

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