The endocranial anatomy of<i>Gogonasus andrewsae</i>Long, 1985 revealed through micro CT-scanning

Holland, Timothy

doi:10.1017/s1755691014000164

Cited by 21 publications

(22 citation statements)

References 32 publications

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“…Endocranial enclosure of the spiracle is generally absent in sarcopterygians (excluding the highly nested Powichthys [17] and Eusthenopteron [25]), the braincase referred to Ligulalepis [6], Acanthodes [29], early chondrichthyans [25], and 'placoderms' [20,25]. The stem gnathostome Janusiscus bears symmetrical endocranial [11,19,[24][25][26]. See also Figure S3.…”

Section: Spiracular Canal Evolutionmentioning

confidence: 99%

The Oldest Actinopterygian Highlights the Cryptic Early History of the Hyperdiverse Ray-Finned Fishes

et al. 2016

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Osteichthyans comprise two divisions, each containing over 32,000 living species [1]: Sarcopterygii (lobe-finned fishes and tetrapods) and Actinopterygii (ray-finned fishes). Recent discoveries from China highlight the morphological disparity of early sarcopterygians and extend their origin into the late Silurian [2-4]. By contrast, the oldest unambiguous actinopterygians are roughly 30 million years younger, leaving a long temporal gap populated by fragments and rare body fossils of controversial phylogenetic placement [5-10]. Here we reinvestigate the enigmatic osteichthyan Meemannia from the Early Devonian (∼415 million years ago) of China, previously identified as an exceptionally primitive lobe-finned fish [3, 7, 11, 12]. Meemannia combines "cosmine"-like tissues taken as evidence of sarcopterygian affinity with actinopterygian-like skull roof and braincase geometry, including endoskeletal enclosure of the spiracle and a lateral cranial canal. We report comparable histological structures in undoubted ray-finned fishes and conclude that they are general osteichthyan features. Phylogenetic analysis places Meemannia as an early-diverging ray-finned fish, resolving it as the sister lineage of Cheirolepis [13] plus all younger actinopterygians. This brings the first appearance of ray-fins more in line with that of lobe-fins and fills a conspicuous faunal gap in the otherwise diverse late Silurian-earliest Devonian vertebrate faunas of the South China Block [4].

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Section: Spiracular Canal Evolutionmentioning

confidence: 99%

The Oldest Actinopterygian Highlights the Cryptic Early History of the Hyperdiverse Ray-Finned Fishes

et al. 2016

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“…Kentuckia Rayner, ; Coccocephalichthys Whitley, (Watson ; Poplin and Véran ); Pteronisculus White, (Nielsen ; Patterson ; Coates )) and sarcopterygians (e.g. Youngolepis Chang and Yu, (Chang ); Eusthenopteron Whiteaves, (Bjerring ; Jarvik ); Gogonasus Long, (Holland )). The large fontanelles presumably formed a point of weakness about which the otic region collapsed, and the fontanelles may in fact appear slightly larger than their original size.…”

Section: Descriptionmentioning

confidence: 99%

Endoskeletal structure inCheirolepis(Osteichthyes,Actinopterygii), An early ray‐finned fish

et al. 2015

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As the sister lineage of all other actinopterygians, the Middle to Late Devonian (Eifelian–Frasnian) Cheirolepis occupies a pivotal position in vertebrate phylogeny. Although the dermal skeleton of this taxon has been exhaustively described, very little of its endoskeleton is known, leaving questions of neurocranial and fin evolution in early ray‐finned fishes unresolved. The model for early actinopterygian anatomy has instead been based largely on the Late Devonian (Frasnian) Mimipiscis, preserved in stunning detail from the Gogo Formation of Australia. Here, we present re‐examinations of existing museum specimens through the use of high‐resolution laboratory‐ and synchrotron‐based computed tomography scanning, revealing new details of the neuro‐cranium, hyomandibula and pectoral fin endoskeleton for the Eifelian Cheirolepis trailli. These new data highlight traits considered uncharacteristic of early actinopterygians, including an uninvested dorsal aorta and imperforate propterygium, and corroborate the early divergence of Cheirolepis within actinopterygian phylogeny. These traits represent conspicuous differences between the endoskeletal structure of Cheirolepis and Mimipiscis. Additionally, we describe new aspects of the parasphenoid, vomer and scales, most notably that the scales display peg‐and‐socket articulation and a distinct neck. Collectively, these new data help clarify primitive conditions within ray‐finned fishes, which in turn have important implications for understanding features likely present in the last common ancestor of living osteichthyans.

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“…They connect with the pore canal system and also extend internally to open into the nasal capsule or meckelian cavity (Miles ; Cheng ). Recently, rostral tubuli have also been found in the non‐Dipnoan taxa Gogonasus and Qingmenodus (Holland ; Lu et al . ).…”

Section: Osteichthyans (Bony Fish)mentioning

confidence: 99%

“…The presence of pore groups in Powichthys and Youngolepis shows that these clusters can be found in marine species. Gogonasus also has a cavity in the neurocranium that has been compared to the rostral organ of coelacanths (Holland ), but this lacks connections to the surface.…”

Section: Osteichthyans (Bony Fish)mentioning

confidence: 99%

Electroreception in early vertebrates: survey, evidence and new information

King

Long

2018

Palaeontology

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Electroreception is widespread in living vertebrates, and is often considered to be a primitive vertebrate character. However, the early evolution of electroreception remains unclear. A variety of structures in early vertebrate fossils have been put forward as potential electroreceptors, but these need to be reassessed in light of the now substantial literature on electroreceptors in living vertebrates. Here we review the evidence for all putative electroreceptors in early vertebrates, and provide new information from CT scans. In the jawless osteostracans, the pore canal system in the dermal skeleton and the lateral and dorsal fields do not resemble electroreceptors in living species. Nevertheless, the presence of a recurrent ramus of the anterior lateral line nerve in osteostracans suggests that electroreceptors were present, by comparison with lampreys. In placoderms, cutaneous sense organs on arthrodire cheek plates are possible electroreceptors. CT data shows that the orientation of these pits is anomalous for electroreceptors, and intimately associated with bone growth. A newly identified type of cheek pit, for which the term 'Young's apparatus' is introduced, is known from only two arthrodire specimens. It is closely associated with the underlying jaw joint, but its precise function is unknown. In osteichthyans, the 'pore group' clusters of early sarcopterygians may have housed electroreceptors. CT data from Devonian lungfish support this interpretation, showing internal morphology consistent with electroreceptors, and innervation via the rostral tubuli underlying the dermal bone of the snout. The early osteichthyan Ligulalepis has pit structures which may be electroreceptors, and were possibly innervated by lateral line nerves. Specialized electroreceptor systems, including elaborated 'pore group' pits in Devonian lungfish and rostral organs in the earliest coelacanths, show that electroreception may have had an important role in niche specialization in early vertebrates. Finally, fossil data does not support the hypothesis that vertebrate hard tissues initially evolved to shield electroreceptors.

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The endocranial anatomy ofGogonasus andrewsaeLong, 1985 revealed through micro CT-scanning

Cited by 21 publications

References 32 publications

The Oldest Actinopterygian Highlights the Cryptic Early History of the Hyperdiverse Ray-Finned Fishes

The Oldest Actinopterygian Highlights the Cryptic Early History of the Hyperdiverse Ray-Finned Fishes

Endoskeletal structure inCheirolepis(Osteichthyes,Actinopterygii), An early ray‐finned fish

Electroreception in early vertebrates: survey, evidence and new information

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