Fins to limbs: what the fossils say<sup>1</sup>

Coates, Michael I.; Jeffery, Jonathan E.; Ruta, Marcello

doi:10.1046/j.1525-142x.2002.02026.x

Cited by 114 publications

(148 citation statements)

References 43 publications

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“…Comparative studies of actinopterygians and ARTICLE sarcopterygians may provide insight into the evolution of both peripheral and central proprioceptive systems. Additionally, fin rays appear to be a primitive feature of sarcopterygian fins 23 . Investigating proprioceptive mechanisms in the fin rays of actinopterygian fishes may inform our understanding of how proprioception in tetrapod limbs arose.…”

Section: Discussionmentioning

confidence: 99%

The function of fin rays as proprioceptive sensors in fish

2013

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The sensation of movement and position of the limbs is critical for normal behaviours in tetrapods. In the bony fishes it is unclear what proprioceptive feedback is provided from the paired fins, the piscine homologues of the tetrapod limbs. Here we test mechanosensory abilities of afferent nerves in the pectoral fin rays, limb structures used by many fish species in propulsion and manoeuvreing. We examine the bluegill sunfish, a fish that uses its pectoral fins extensively in locomotion. We find that the activity of fin ray nerve fibres reflects the amplitude and velocity of fin ray bending. Spike sorting analyses demonstrate the presence of both slowly and rapidly adapting afferent nerve fibres. The fin sensory abilities we describe substantially expand the diversity of known vertebrate proprioceptive capabilities, and suggest that the pectoral fins need to be considered as possible proprioceptive sensors in studies of their functional morphology, movement and evolution.

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Section: Discussionmentioning

confidence: 99%

The function of fin rays as proprioceptive sensors in fish

2013

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“…The lobed fins of the coelacanth exhibit structures that are intermediate between fish and tetrapods, as represented by the presence of ray-like dermal bones (lepidotrichia), as well as a tetrapod-like robust endochondral internal skeleton, which are the ancestral characteristics of primitive sarcopterygians (Figs. 2, 6A; Coates et al 2002;Friedman et al 2007). The and genes encode actinoidin proteins, which are essential for the formation of lepidotrichia in teleost fishes and are absent in tetrapods (Zhang et al 2010).…”

Section: Genes For Limb Developmentmentioning

confidence: 99%

“…Thus, an innovative change occurred in the olfactory organ of vertebrates during the habitat transition from water to land. Similarly, the robust endoskeletal structures observed in land vertebrates are believed to be a result of adaptation to terrestrial life (Coates et al 2002). Investigation of such phenotypic alterations is quite important to elucidate how adaptation to terrestrial life was accomplished during evolution.…”

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confidence: 99%

Coelacanth genomes reveal signatures for evolutionary transition from water to land

et al. 2013

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Coelacanths are known as ''living fossils,'' as they show remarkable morphological resemblance to the fossil record and belong to the most primitive lineage of living Sarcopterygii (lobe-finned fishes and tetrapods). Coelacanths may be key to elucidating the tempo and mode of evolution from fish to tetrapods. Here, we report the genome sequences of five coelacanths, including four Latimeria chalumnae individuals (three specimens from Tanzania and one from Comoros) and one L. menadoensis individual from Indonesia. These sequences cover two African breeding populations and two known extant coelacanth species. The genome is~2.74 Gbp and contains a high proportion (~60%) of repetitive elements. The genetic diversity among the individuals was extremely low, suggesting a small population size and/or a slow rate of evolution. We found a substantial number of genes that encode olfactory and pheromone receptors with features characteristic of tetrapod receptors for the detection of airborne ligands. We also found that limb enhancers of bmp7 and gli3, both of which are essential for limb formation, are conserved between coelacanth and tetrapods, but not ray-finned fishes. We expect that some tetrapod-like genes may have existed early in the evolution of primitive Sarcopterygii and were later co-opted to adapt to terrestrial environments. These coelacanth genomes will provide a cornerstone for studies to elucidate how ancestral aquatic vertebrates evolved into terrestrial animals.

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“…Elginerpeton and Obruchevichthys were first, between 385 and 375 MYBP, followed several million years later by a modest radiation that included Ventastega, Ichythostega, Acanthostega, Tulerpeton, Metaxygnathus, and Hynerpeton. Although most of these taxa possessed limbs (although this is not certain for Elginerpeton and Obruchevichthys), all of these taxa have been interpreted as fully aquatic, rather than terrestrial (5)(6)(7). Their respiratory systems are poorly known, but osteology suggests that they were able to derive some amount of O 2 from water instead of being entirely air breathing (8).…”

mentioning

confidence: 99%

Confirmation of Romer's Gap as a low oxygen interval constraining the timing of initial arthropod and vertebrate terrestrialization

Ward

Labandeira

Laurin

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

133

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The first terrestrialization of species that evolved from previously aquatic taxa was a seminal event in evolutionary history. For vertebrates, one of the most important terrestrialized groups, this event was interrupted by a time interval known as Romer's Gap, for which, until recently, few fossils were known. Here, we argue that geochronologic range data of terrestrial arthropods show a pattern similar to that of vertebrates. Thus, Romer's Gap is real, occupied an interval from 360 million years before present (MYBP) to 345 MYBP, and occurred when environmental conditions were unfavorable for air-breathing, terrestrial animals. These model results suggest that atmospheric oxygen levels were the major driver of successful terrestrialization, and a low-oxygen interval accounts for Romer's Gap. Results also show that terrestrialization among members of arthropod and vertebrate clades occurred in two distinct phases. The first phase was a 65-million-year ( (1) indicates that arthropods, with species interpreted as fully land-based before 400 million years before present (MYBP) (2), preceded vertebrates onto land by tens of millions of years. The first body fossils identified as stegocephalians (limbed vertebrates) are known from strata Ϸ370 MYBP, such that the appearance of the limb with digits, the loss of the opercular apparatus, and the development of other characters that subsequently allowed a terrestrial lifestyle, presumably occurred during the 25-My interval between 385 and 360 MYBP (3, 4). Most of our understanding about these crucial vertebrate events comes from only a few freshwater deposits from Euramerican localities, with outcrops in Greenland producing the most prolific stegocephalian remains. Elginerpeton and Obruchevichthys were first, between 385 and 375 MYBP, followed several million years later by a modest radiation that included Ventastega, Ichythostega, Acanthostega, Tulerpeton, Metaxygnathus, and Hynerpeton. Although most of these taxa possessed limbs (although this is not certain for Elginerpeton and Obruchevichthys), all of these taxa have been interpreted as fully aquatic, rather than terrestrial (5-7). Their respiratory systems are poorly known, but osteology suggests that they were able to derive some amount of O 2 from water instead of being entirely air breathing (8). These stegocephalians disappeared soon thereafter, followed rapidly by rare appearances of limbed vertebrates. This temporal gap has long been called Romer's Gap, and until recently it was unknown whether this hiatus was due to a combination of unfavorable taphonomic conditions and collection failure or whether it represented an interval of intrinsically low diversity and an abundance of limbed vertebrates. Romer's Gap separates occurrences of the earliest (Late Devonian) aquatic stegocephalians from a much larger adaptive radiation that included the first terrestrial vertebrates that commenced during the Visean stage of the Early Carboniferous. Although new collections have partly filled Romer's Gap (9), including the d...

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Fins to limbs: what the fossils say¹

Cited by 114 publications

References 43 publications

The function of fin rays as proprioceptive sensors in fish

The function of fin rays as proprioceptive sensors in fish

Coelacanth genomes reveal signatures for evolutionary transition from water to land

Confirmation of Romer's Gap as a low oxygen interval constraining the timing of initial arthropod and vertebrate terrestrialization

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Fins to limbs: what the fossils say1

Cited by 114 publications

References 43 publications

The function of fin rays as proprioceptive sensors in fish

The function of fin rays as proprioceptive sensors in fish

Coelacanth genomes reveal signatures for evolutionary transition from water to land

Confirmation of Romer's Gap as a low oxygen interval constraining the timing of initial arthropod and vertebrate terrestrialization

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Fins to limbs: what the fossils say¹