Carboniferous dipnoans from Nova Scotia

Sternberg, Rob

doi:10.2475/ajs.239.11.836

Cited by 4 publications

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“…). The distinction between Sagenodus and Ctenodus can be somewhat blurred (see for example the debate surrounding ‘ Sagenodus ’ plicatus : Dawson ; Romer and Smith ; Sternberg ; Baird ; Schultze and Chorn ), but in general the two are differentiated by radiation being weak or absent in the tooth ridges of the former (Schultze and Chorn ). Sagenodus is only distinguishable from the closely related Straitonia (Upper Carboniferous of Midlothian, Scotland) by the arrangement of the dermal bones of the skull (Thomson ); the dentition of Straitonia is unknown, but generally assumed to be similar to that of Sagenodus (Thomson ; Campbell and Barwick , ), so it cannot be excluded that the specimens described here belong to Straitonia .…”

Section: Family Sagenodontidae Woodward Genus ?Sagenodus Owen ?Samentioning

confidence: 99%

Carboniferous (Tournaisian) fish assemblages from the Isle of Bute, Scotland: systematics and palaeoecology

et al. 2014

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We describe fish assemblages from the Carboniferous (mid-to late Tournaisian) Ballagan Formation at two localities, Hawk's Nib and Mill Hole, on the Isle of Bute, Scotland. Fossil material occurs in thin, locally reworked dolomitic limestone beds, interpreted as the deposits of very shallow lakes or lagoons, developed on, or adjacent to, a seasonally dry coastal plain. The mostly disarticulated fossils comprise isolated teeth, mandibles, scales, tesserae, dermal bones, lepidotrichia and vertebrae. The fauna includes rhizodonts (cf. Archichthys portlocki, cf. Strepsodus sauroides), lungfish (Sagenodus sp.), other sarcopterygians (Megalichthys sp.), one shark (Ageleodus pectinatus), climatiiform acanthodians and indeterminate actinopterygians. The Mill Hole assemblage is especially noteworthy because it includes some putative juvenile forms (Archichthys and Sagenodus). A critical review of the habitat preferences of the documented taxa suggests that most were either euryhaline or, in the case of Archichthys, probably endemic to brackish or freshwater settings. The Bute fish beds fall within a crucial evolutionary period during which many fish and other animal groups were infiltrating nonmarine environments, either passively or actively. It may be that lakes and lagoons may have functioned as protected nurseries for juveniles during this wave of colonization.

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Section: Family Sagenodontidae Woodward Genus ?Sagenodus Owen ?Samentioning

confidence: 99%

Carboniferous (Tournaisian) fish assemblages from the Isle of Bute, Scotland: systematics and palaeoecology

et al. 2014

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“…NBMG 10740 shows more prominent separated apices than C. cristatus (Sharp & Clack , fig. 2) and C. murchisoni (Sternberg , figs 1–3). These prominent apices are similar to C. interruptus (see Sharp & Clack , figs 5, 14).…”

Section: Systematic Palaeontologymentioning

confidence: 99%

Fish and tetrapod communities across a marine to brackish salinity gradient in the Pennsylvanian (early Moscovian) Minto Formation of New Brunswick, Canada, and their palaeoecological and palaeogeographical implications

et al. 2016

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42The cosmopolitan biogeography of many fish genera strongly indicates marine-based 43 dispersal, while strontium isotopic data suggest these same fish were exposed, at times, to ). An intriguing characteristic of this episode was the apparent widespread adoption of 68 a euryhaline habit amongst organisms as diverse as microconchids, ostracodes, xiphosurans 69 and fish (Anderson and Shuster 2003; Carpenter et al. 2011; Bennett et al. 2012; Gierlowski-70 Kordesch and Cassle 2015). Euryhaline animals are relatively rare in modern ecosystems 71 (Edwards and Marshall 2013; McCormick et al. 2013), and their dominance in Carboniferous 72 times suggests marine communities converged on similar osmoregulatory strategies in order 73 to utilise empty non-marine coastal ecospace for feeding and breeding (Williams et al. 2006; 74 Carpenter et al. 2014), prior to the widespread colonisation of freshwater tracts further inland. 75The mid-Carboniferous diversification event coincided with a sharp growth of 76Gondwanan ice sheets and the onset of significant Milankovitch-driven glacio-eustatic 86Much recent attention has been given to the apparent dominance of a euryhaline mode 87 of life amongst mid-Carboniferous fish communities (Schultze 2009; Carpenter et al. 2011 Carpenter et al. , 88 2014Carpenter et al. , 2015. However, consensus regarding ecology is currently lacking, with some 89 researchers arguing on palaeogeographic, sedimentological and geochemical grounds that fish 90 taxa, especially xenacanthid sharks (Masson and Rust 1984), may have been obligate 91 freshwater organisms (Śtamberg and Zajíc 2008;Fischer et al. 2011 Fischer et al. , 2013 Montañez and 92 Cecil 2013). In this paper, we describe a new fish fauna from the Carboniferous 93 (Pennsylvanian) of New Brunswick, Canada (Fig. 1A), and demonstrate -based on 94 independent indicators of palaeo-salinity -that fish taxa existed across a brackish to marine 95 gradient, and that communities must therefore have been euryhaline. We discuss how these 96 new findings improve understanding of Carboniferous fish ecology and the mid- 97Carboniferous diversification of non-marine ecosystems in particular. The fish fossils reported here were obtained from opencast mine sites (now reclaimed) within 102 the Minto Coalfield, Queens County, New Brunswick, Canada (Fig. 1A-C 98 +REVISE FOR TETRAPOD STORY 123Extensive borehole arrays indicate that this basal unconformity is marked by a major silcrete 124 paleosol, up to 9 m thick in places (Sullivan 1981; St Peter 2000), which mantles the 125 basement complex and indicates seasonally-dry climate weathering over the preceding (Fig. 3A), implying that the basin deepened towards the 137 southwest, and sediment progressively onlapped towards the northeast; and (2) NE-SW- Coal, fine towards the southwest (Fig. 3B) and suggest sediment transport in that direction. 140We note, however, that this inferred palaeoflow direction opposes regional patterns of Geological Surveys Branch, Fredericton (Fig. 4A). 154The low...

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“…Gardiner () erroneously transferred C. cristatus without explanation to the lungfish genus Sagenodus . Presumably he had confused Ctenoptychius cristatus with Ctenodus cristatus Agassiz (), which was identified by Sternberg () as a junior synonym of Sagenodus cristatus . To complicate matters further, Conchodus plicatus (= Ctenodus or Sagenodus ; Schultze and Chorn ; see also below) from Joggins was also discussed in those papers.…”

Section: Historical Review Of Dawson's Speciesmentioning

confidence: 99%

“…Although figured under the name Conchodus plicatus , Dawson () offered no justification for placing it in a new species, merely stating that it ‘appears to belong to M'Coy's genus Conchodus’ (p. 209). Dawson's specimen was transferred to Ctenodus by Woodward () and then to Sagenodus by Sternberg (), in each case retaining the plicatus species epithet. Baird () argued that the specimen was too fragmentary for species‐level identification, and dismissed Sagenodus plicatus as a nomen vanum .…”

Section: Historical Review Of Dawson's Speciesmentioning

confidence: 99%

“…This was also the position of Schultze and Chorn (), although neither author provided a redescription. Therefore, the most recent detailed description of the specimen is Sternberg (), who considered it to be similar to Sagenodus periprion Cope (). So far as we are aware, no other material has been, even tentatively, assigned to this species.…”

Section: Historical Review Of Dawson's Speciesmentioning

confidence: 99%

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Early Pennsylvanian (Langsettian) fish assemblages from the Joggins Formation, Canada, and their implications for palaeoecology and palaeogeography

et al. 2015

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A review of all available specimens of fossil fishes from the classic Pennsylvanian Joggins locality of Nova Scotia, Canada, reveals the existence of a diverse community of chondrichthyans (xenacanthids, ctenacanthids and the enigmatic Ageleodus), acanthodians (gyracanthids), sarcopterygians (rhizodontids, megalichthyids, rhizodopsids and dipnoans) and actinopterygians (haplolepids). Reassessment of supposed endemic species (Ctenoptychius cristatus, Sagenodus plicatus, Gyracanthus duplicatus) indicates they are invalid, and overall, the assemblage comprises cosmopolitan taxa that were widespread around the coasts of tropical Pangaea. Strontium isotope analysis of fish remains and a critical study of their facies context suggest that these fish communities occupied bodies of water with salinities across the marine-freshwater spectrum. This preponderance of euryhaline forms implies a community structure quite distinct from that of today and might represent a transitory phase prior to the establishment of fully freshwater fish communities. Interpretation of fish ecology provides further evidence that the Joggins Formation was deposited in a paralic setting, and the recognition of one previously undetected brackish incursion strengthens the link between sedimentary cycles at Joggins and Milankovitch-induced glacio-eustatic change. Furthermore, interregional correlation of these marine transgressions supports palynostratigraphical arguments for an early Langsettian age for the Joggins Formation. This places tighter constraints on the age of the earliest known crown amniote, Hylonomus lyelli, an important calibration point used in phylogenomic studies.

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Carboniferous dipnoans from Nova Scotia

Cited by 4 publications

References 0 publications

Carboniferous (Tournaisian) fish assemblages from the Isle of Bute, Scotland: systematics and palaeoecology

Carboniferous (Tournaisian) fish assemblages from the Isle of Bute, Scotland: systematics and palaeoecology

Fish and tetrapod communities across a marine to brackish salinity gradient in the Pennsylvanian (early Moscovian) Minto Formation of New Brunswick, Canada, and their palaeoecological and palaeogeographical implications

Early Pennsylvanian (Langsettian) fish assemblages from the Joggins Formation, Canada, and their implications for palaeoecology and palaeogeography

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