Structure and habits of the ‘living fossil’ pelecypod
            <i>Neotrigonia</i>

Tevesz, Michael J. S.

doi:10.1111/j.1502-3931.1975.tb00937.x

Cited by 30 publications

(30 citation statements)

References 2 publications

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“…This view was also supported by Tashiro & Matsuda (), Lazo () and Luci (). Such life position resulted in corselets exposed above the sediment–water interface, and as a consequence, they were encrusted syn vivo (quite similar to the pattern observed in modern trigonioids; see Tevesz ). Further, post‐mortem encrustation could happen both on corselets and flanks of specimens that were disinterred after death.…”

Section: Methodssupporting

confidence: 55%

Palaeoecological analysis of a sclerobiont fauna on a single basibiont across the Valanginian of the Neuquén Basin, west-central Argentina

Luci

Toscano

Lazo

2019

LET

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Sclerobiont communities have proven their environmental and taphonomic value in extant and past settings; studies are beginning to quantify and evaluate their changes across time. Through the Valanginian of the Neuquén Basin, Argentina, trigonioids of the genus Steinmanella present an almost continuous record. Materials were collected from shales and shell beds across second‐order systems tracts (LST, TST and HST). Their sclerobiont communities were characterized and compared across systems tracts and facies. In addition, a link between them and coeval oyster mass occurrences (OMOs) was investigated, since studies on other local sclerobiont communities have consistently shown pronounced oyster dominance. Eleven sclerobiont taxa were found on Steinmanella (bryozoans, bivalves, foraminifers and polychaetes), of which oysters are usually strongly dominant but for the TST, in which their dominance is diminished. The sclerobiont community has a simple structure and interspecific relationships and competition for space seem to have had little importance. Few differences in richness, taxonomy and other parameters were found between facies. Across systems tracts, features of the sclerobiont communities are differentiated mostly from swings in relative abundance of taxa. The lowered oyster dominance in the TST may reflect a source–sink dynamics between OMOs (sources) and Steinmanella as sinks in shallower, soft substrate settings. Likely the sea‐level rise temporally drowned the oyster carbonate factory, resulting in decreased larvae emigration to the sinks and lowered oyster dominance during the TST.

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Section: Methodssupporting

confidence: 55%

Palaeoecological analysis of a sclerobiont fauna on a single basibiont across the Valanginian of the Neuquén Basin, west-central Argentina

Luci

Toscano

Lazo

2019

LET

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“…As described above, Neotrigonia is the only genus in the Heteroconchia to possess filibranch ctenidia. The presence of a veliger has not been confirmed but is presumed (Tevesz, 1975; Prezant, 1998; Ó Foighil & Graf, 2000).…”

Section: Discussionmentioning

confidence: 99%

Palaeoheterodont diversity (Mollusca: Trigonioida + Unionoida): what we know and what we wish we knew about freshwater mussel evolution

Graf¹,

Cummings

2006

Zoological Journal of the Linnean Society

154

191

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The Palaeoheterodonta is a diverse clade consisting of the freshwater bivalve order Unionoida and its marine sister group, Neotrigonia . Neotrigonia is the sole surviving genus of the Trigonioida, known from only six species in Australian waters. Unionoids (freshwater mussels), in contrast, are widespread on all continents except Antarctica and are represented by c . 900 species. Discussion is biased towards the freshwater mussel condition, but Neotrigonia is crucial as a 'living fossil' for establishing the plesiomorphic states of unionoid synapomorphies. Neotrigonia retains many of the characters of the ancestral heteroconch. Our object is to provide evidential support for the natural classification of the extant Palaeoheterodonta. A supermatrix of 50 taxa and 1183 characters was constructed from 62 previously published DNA sequences of mitochondrial cytochrome oxidase subunit I (COI) and 28S nuclear ribosomal DNA, 15 novel sequences, and 59 morphological characters. Published COI sequences for Coelatura aegyptiaca , Pseudomulleria dalyi , and Obliquaria reflexa were treated as potentially problematic because of their inconsistency under different methodological assumptions and conflict with other datasets. Each partition was analysed under the criterion of parsimony separately and in combined analyses; analyses were run both with and without the problematic sequences. From our 'combined evidence' topology (with problematic sequences excluded), the Unionoida is monophyletic on the basis of eight synapomorphies, including larval parasitism, brood protection, and restriction to freshwater. The order is composed of six families in two superfamilies, Unionoidea and Etherioidea: ((Unionidae + Margaritiferidae) + (Hyriidae + (Etheriidae + (Mycetopodidae + Iridinidae)))). The morphological synapomorphies of these taxa are discussed with an emphasis on both the diagnosing of taxa and highlighting areas of ambiguity and missing data. Three appendices provide descriptions of the morphological characters (Appendix 1), a diagnosis of apomorphies for all branches of the phylogeny (Appendix 2), and a family-level classification of the extant Palaeoheterodonta, including a complete synonymy (Appendix 3).

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“…An important review of living Neotrigonia has been made by Tevesz (1975), who studied the genus and its life habits in the laboratory (see also Morton 1987). N. margaritacea inhabits current-dominated channels at a depth of 20 m and with mean water velocities of 5 knots that indicate a medium energy environment.…”

Section: Palaeoenvironmentsmentioning

confidence: 99%

Ecology and evolution of Jurassic trigoniid bivalves in Europe

Francis

Hallam

2003

LET

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A modern palaeobiological approach to the taxonomy, making full allowance for a wide range of variation, has allowed the distinction of 22 Jurassic trigoniid species in Europe, grouped into 7 genera. Most species were con®ned to shallow marine habitats ranging up to a few tens of metres in depth but were adapted to low energy environments as well as environments of moderate to high energy. The presence of external ornament on the shell¯anks was probably an adaptation to facilitate burrowing, but in the absence of useful external ornament other adaptations to increase burrowing ef®ciency may have been realized by the development of an elongate shape. Because their occurrence in Jurassic strata is only intermittent, con®dent inferences on evolutionary patterns are limited to the two commonest genera, Trigonia and Myophorella. Phyletic size increase has been recognized in the latter but not the former genus. The calculated species longevities correspond fairly closely with those established for Jurassic bivalve species in general. The mode of speciation is dominantly punctuational, but only one likely example of species splitting is recognized.

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Structure and habits of the ‘living fossil’ pelecypod Neotrigonia

Cited by 30 publications

References 2 publications

Palaeoecological analysis of a sclerobiont fauna on a single basibiont across the Valanginian of the Neuquén Basin, west-central Argentina

Palaeoecological analysis of a sclerobiont fauna on a single basibiont across the Valanginian of the Neuquén Basin, west-central Argentina

Palaeoheterodont diversity (Mollusca: Trigonioida + Unionoida): what we know and what we wish we knew about freshwater mussel evolution

Ecology and evolution of Jurassic trigoniid bivalves in Europe

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