A possible Cambrian stem-group gnathiferan-chaetognath from the Weeks Formation (Miaolingian) of Utah

Morris, Simon Conway; Smith, R. D. A.; Cuthill, Jennifer F. Hoyal; Bonino, Enrico; Lerosey‐Aubril, Rudy

doi:10.1017/jpa.2020.4

Cited by 5 publications

(4 citation statements)

References 71 publications

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“…This enabled us to exclude the taxa that only occur in stratigraphic intervals barren of non-biomineralized fossils, such as the lower and upper parts of the Marjum Formation or the lower part of the Weeks Formation. We then updated the resulting dataset to include omitted ( Caron, Conway Morris & Cameron, 2013 ) or more recently published contributions ( Conway Morris et al, 2015 ; Maletz & Steiner, 2015 ; Smith, 2015 ; Foster & Gaines, 2016 ; Pates, Daley & Ortega-Hernández, 2017 ; Lerosey-Aubril & Pates, 2018 ; Lerosey-Aubril & Skabelund, 2018 ; Lerosey-Aubril et al, 2018 , 2020 ; Pates, Daley & Lieberman, 2018 ; Pates, Daley & Ortega-Hernández, 2018 ; Conway Morris et al, 2020 ; Lerosey-Aubril, Skabelund & Ortega-Hernández, 2020 ) and some new discoveries (R. Lerosey-Aubril, 2019, personal observation). Finally, we complemented the database with information on lifestyle for each taxon.…”

Section: Methodsmentioning

confidence: 99%

The diverse radiodont fauna from the Marjum Formation of Utah, USA (Cambrian: Drumian)

Pates

Lerosey‐Aubril

Daley

et al. 2021

PeerJ

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Radiodonts have long been known from Cambrian deposits preserving non-biomineralizing organisms. In Utah, the presence of these panarthropods in the Spence and Wheeler (House Range and Drum Mountains) biotas is now well-documented. Conversely, radiodont occurrences in the Marjum Formation have remained scarce. Despite the large amount of work undertaken on its diverse fauna, only one radiodont (Peytoia) has been reported from the Marjum Biota. In this contribution we quadruple the known radiodont diversity of the Marjum fauna, with the description of the youngest members of two genera, Caryosyntrips and Pahvantia, and that of a new taxon Buccaspinea cooperi gen. et sp. nov. This new taxon can be identified from its large oral cone bearing robust hooked teeth with one, two, or three cusps, and by the unique endite morphology and organisation of its frontal appendages. Appendages of at least 12 podomeres bear six recurved plate-like endites proximal to up to four spiniform distal endites. Pahvantia hastata specimens from the Marjum Formation are particularly large, but otherwise morphologically indistinguishable from the carapace elements of this species found in the Wheeler Formation. One of the two new Caryosyntrips specimens can be confidently assigned to C. camurus. The other bears the largest spines relative to appendage length recorded for this genus, and possesses endites of variable size and unequal spacing, making its taxonomic assignment uncertain. Caryosyntrips, Pahvantia, and Peytoia are all known from the underlying Wheeler Formation, whereas isolated appendages from the Spence Shale and the Wheeler Formation, previously assigned to Hurdia, are tentatively reidentified as Buccaspinea. Notably, none of these four genera occurs in the overlying Weeks Formation, providing supporting evidence of a faunal restructuring around the Drumian-Guzhangian boundary. The description of three additional nektonic taxa from the Marjum Formation further documents the higher relative proportion of free-swimming species in this biota compared to those of the Wheeler and Weeks Lagerstätten. This could be related to a moderate deepening of the basin and/or changing regional ocean circulation at this time.

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Section: Methodsmentioning

confidence: 99%

The diverse radiodont fauna from the Marjum Formation of Utah, USA (Cambrian: Drumian)

Pates

Lerosey‐Aubril

Daley

et al. 2021

PeerJ

Self Cite

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“…Of the myriad worm-like taxa with similar overall dimensions (e.g. [14,64,65]), perhaps the most relevant is Acosmia maotiania [66], a Chengjiang fossil with lateral tubes alongside its gut (see figs 1 and 3 of [66]). However, Iotuba and Acosmia differ in almost every morphological detail.…”

Section: Resultsmentioning

confidence: 99%

“…Ipoliknus [70] bears ‘sclerites’ that resemble the robust, cuticularized papillae of Iotuba , so conceivably also belongs to the papilla-bearing subclade of Cirratuliformia [24]—though available material is inadequate to substantiate this hypothesis. Detailed comparison with the undescribed ‘New Taxon 1’ [32,66] or Dakorhachis [65], whose segmented trunk and cage of terminal spines are somewhat reminiscent of Iotuba , is precluded by the limited preservation of available material.…”

Section: Discussionmentioning

confidence: 99%

The Cambrian cirratuliform Iotuba denotes an early annelid radiation

2023

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The principal animal lineages (phyla) diverged in the Cambrian, but most diversity at lower taxonomic ranks arose more gradually over the subsequent 500 Myr. Annelid worms seem to exemplify this pattern, based on molecular analyses and the fossil record: Cambrian Burgess Shale-type deposits host a single, early-diverging crown-group annelid alongside a morphologically and taxonomically conservative stem group; the polychaete sub-classes diverge in the Ordovician; and many orders and families are first documented in Carboniferous Lagerstätten. Fifteen new fossils of the ‘phoronid’ Iotuba (=Eophoronis) chengjiangensis from the early Cambrian Chengjiang Lagerstätte challenge this picture. A chaetal cephalic cage surrounds a retractile head with branchial plates, affiliating Iotuba with the derived polychaete families ‘Flabelligeridae’ and Acrocirridae. Unless this similarity represents profound convergent evolution, this relationship would pull back the origin of the nested crown groups of Cirratuliformia, Sedentaria and Pleistoannelida by tens of millions of years—indicating a dramatic unseen origin of modern annelid diversity in the heat of the Cambrian ‘explosion’.

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“…Even the relationships among Trochozoa are far from being resolved, namely the monophyly of Polyzoa (Bryozoa + Entoprocta + Cycliophora) has regained credit recently ( Khalturin et al 2022 ; but see ( Nesnidal et al 2013 ; Kocot 2016 ; Bleidorn 2019 ; Laumer et al 2019 ). Outside Trochozoa, Rouphozoa (Platyhelminthes + Gastrotricha) and Chaetognathifera (Syndermata + Micrognathozoa + Gnathostomulida + Chaetognatha) are supported by most of the phylogenetic analyses ( Struck et al 2014 ; Laumer et al 2015 ; Kocot et al 2017 ; Laumer et al 2019 ; Conway Morris et al 2020 ).…”

Section: Introductionmentioning

confidence: 96%

The Evolution and Characterization of the RNA Interference Pathways in Lophotrochozoa

Formaggioni,

Cavalli,

Hamada

et al. 2024

Genome Biology and Evolution

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In animals, three main RNA interference mechanisms have been described so far, which respectively maturate three types of small noncoding RNAs (sncRNAs): miRNAs, piRNAs and endo-siRNAs. The diversification of these mechanisms is deeply linked with the evolution of the Argonaute gene superfamily since each type of sncRNA is typically loaded by a specific Argonaute homolog. Moreover, other protein families play pivotal roles in the maturation of sncRNAs, like the DICER ribonuclease family, whose DICER1 and DICER2 paralogs maturate respectively miRNAs and endo-siRNAs. Within Metazoa, the distribution of these families has been only studied in major groups, and there are very few data for clades like Lophotrochozoa. Thus, we here inferred the evolutionary history of the animal Argonaute and DICER families including 43 lophotrochozoan species. Phylogenetic analyses along with newly sequenced sncRNA libraries suggested that in all Trochozoa the proteins related to the endo-siRNA pathway have been lost, a part of them in some phyla (i.e., Nemertea, Bryozoa, Entoprocta), while all of them in all the others. On the contrary, early diverging phyla, Platyhelminthes and Syndermata, showed a complete endo-siRNA pathway. On the other hand, miRNAs were revealed the most conserved and ubiquitous mechanism of the metazoan RNA interference machinery, confirming their pivotal role in animal cell regulation.

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A possible Cambrian stem-group gnathiferan-chaetognath from the Weeks Formation (Miaolingian) of Utah

Cited by 5 publications

References 71 publications

The diverse radiodont fauna from the Marjum Formation of Utah, USA (Cambrian: Drumian)

The diverse radiodont fauna from the Marjum Formation of Utah, USA (Cambrian: Drumian)

The Cambrian cirratuliform Iotuba denotes an early annelid radiation

The Evolution and Characterization of the RNA Interference Pathways in Lophotrochozoa

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