Copepod Mandible Palynomorphs From the Nolichucky Shale (Cambrian, Tennessee): Implications for the Taphonomy and Recovery of Small Carbonaceous Fossils

Harvey, Thomas H. P.; Pedder, Brian E.

doi:10.2110/palo.2012.p12-124r

Cited by 30 publications

(26 citation statements)

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“…This implies that the origin of copepods may be earlier (probably Cambrian age) than this period [82, 83]. It is because all copepod taxa in this study belong to the Infraclass Neocopepoda, and Platycopioida (the other infraclass Progymnoplea) is known to be the most primitive group of copepods and possibly closer to the ancestral form [5, 12].…”

Section: Discussionmentioning

confidence: 99%

Phylogenomic analysis of Copepoda (Arthropoda, Crustacea) reveals unexpected similarities with earlier proposed morphological phylogenies

Eyun

2017

BMC Evol Biol

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BackgroundCopepods play a critical role in marine ecosystems but have been poorly investigated in phylogenetic studies. Morphological evidence supports the monophyly of copepods, whereas interordinal relationships continue to be debated. In particular, the phylogenetic position of the order Harpacticoida is still ambiguous and inconsistent among studies. Until now, a small number of molecular studies have been done using only a limited number or even partial genes and thus there is so far no consensus at the order-level.ResultsThis study attempted to resolve phylogenetic relationships among and within four major copepod orders including Harpacticoida and the phylogenetic position of Copepoda among five other crustacean groups (Anostraca, Cladocera, Sessilia, Amphipoda, and Decapoda) using 24 nuclear protein-coding genes. Phylogenomics has confirmed the monophyly of Copepoda and Podoplea. However, this study reveals surprising differences with the majority of the copepod phylogenies and unexpected similarities with postembryonic characters and earlier proposed morphological phylogenies; More precisely, Cyclopoida is more closely related to Siphonostomatoida than to Harpacticoida which is likely the most basally-branching group of Podoplea. Divergence time estimation suggests that the origin of Harpacticoida can be traced back to the Devonian, corresponding well with recently discovered fossil evidence. Copepoda has a close affinity to the clade of Malacostraca and Thecostraca but not to Branchiopoda. This result supports the hypothesis of the newly proposed clades, Communostraca, Multicrustacea, and Allotriocarida but further challenges the validity of Hexanauplia and Vericrustacea.ConclusionsThe first phylogenomic study of Copepoda provides new insights into taxonomic relationships and represents a valuable resource that improves our understanding of copepod evolution and their wide range of ecological adaptations.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-017-0883-5) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Phylogenomic analysis of Copepoda (Arthropoda, Crustacea) reveals unexpected similarities with earlier proposed morphological phylogenies

Eyun

2017

BMC Evol Biol

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“…If the palaeontological case for arthropod origins and diversification in the Cambrian rather than the Neoproterozoic is accurate, recovery of arthropod body fossils referable to such extant crustacean groups as Branchiopoda and Copepoda in palynological samples from the late early and late Cambrian (Harvey and Butterfield ; Harvey et al . ; Harvey and Pedder ) signals an explosive radiation of crustaceans, and implicitly other arthropods, during the Cambrian. The identification of these fossils as members of extant crustacean total groups contributes to molecular and morphological clock estimates of rates of evolution amongst early arthropods several times faster than background levels regardless of how deeply in the Ediacaran the origin of Arthropoda is allowed to extend (Lee et al .…”

Section: Relationships Between Major Arthropod Groups: a Molecular Scmentioning

confidence: 99%

Origins and early evolution of arthropods

2014

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Phylogenomics reconstructs an arthropod tree in which a monophyletic Arthropoda splits into Pycnogonida + Euchelicerata and Myriapoda + Pancrustacea. The same chelicerate-mandibulate groups are retrieved with morphological data sets, including those encompassing most taxa known from Palaeozoic Konservat-Lagerst€ atten. With respect to the interrelationships of the three extant clades of Panarthropoda, a sister group relationship between Onychophora and Arthropoda is endorsed by transcriptomics and microRNAs, although this hypothesis forces homoplasy in characters of the segmental ganglia that are shared by tardigrades and arthropods. Cambrian lobopodians, dinocaridids, bivalved arthropods and fuxianhuiids document the successive appearance of characteristic arthropod features in the stem lineage of Euarthropoda (crown-group arthropods). Molecular dating suggests that arthropods had their origin and initial diversification in the Ediacaran, but no convincing palaeontological evidence for Panarthropoda is available until the earliest Cambrian.

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“…They might also have been the most recalcitrant part of an otherwise hardly preservable organism. Harvey & Pedder () made a similar observation about mandibles in Cambrian SCF assemblages.…”

Section: Resultsmentioning

confidence: 64%

“…The taphonomic history of the Winneshiek SCFs that allowed their preservation with finest details may have been similar to that of crustacean remains from the Cambrian of Canada reported from the Mount Cap Formation (lower Cambrian), the Deadwood Formation (middle‐upper Cambrian), the Earlie Formation (middle Cambrian) and the Nolichucky Shale (middle‐upper Cambrian) (Harvey & Butterfield ; Butterfield & Harvey ; Harvey et al . ,b; Harvey & Pedder ). The fossil record of crustaceans in the Ordovician is largely represented by easily preserved ostracod shells and phyllocarid carapaces (Sepkoski ; Vannier et al .…”

Section: Discussionmentioning

confidence: 99%

“…) and branchiopod, copepod and ostracod‐type mandibles (Harvey & Butterfield ; Harvey et al . ,b; Harvey & Pedder ), providing valuable insight into the evolution and ecology of early crustaceans. The attempt to search for organic microfossils in the Winneshiek Shale has now yielded numerous objects that we tentatively identify as crustacean filter plates and coxae of a diminutive euchelicerate, which are described herein.…”

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confidence: 99%

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Exceptionally preserved arthropodan microfossils from the Middle Ordovician Winneshiek Lagerstätte, Iowa, USA

Nowak

Harvey

Liu

et al. 2018

LET

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The Middle Ordovician (Darriwilian) Winneshiek Shale from Winneshiek County, Iowa, USA, hosts a Konservat‐Lagerstätte that has yielded a diverse fauna including soft‐bodied fossils. The shale is rich in organic content; in particular, algal material and fragmentary cuticular remains. Palynological acid treatment alongside modified, low‐manipulation processing enables the extraction of these ‘small carbonaceous fossils’ (SCFs) from the matrix, allowing a more detailed view of their morphology. Together these methods have yielded exceptionally well‐preserved crustacean‐type setae and a population of distinctive microfossils which we identify as the feeding appendages of a small‐bodied arthropod. We present two hypotheses for their identity: as either pancrustacean mandibles, or euchelicerate coxae. Overall, the detailed topological similarities and implied functional equivalence to the coxae of xiphosurid chelicerates, in particular, outweigh the resemblance to certain branchiopodan and hexapodan mandibles. In turn, however, the restricted size range and lack of associated limb or carapace fragments pose a taphonomic conundrum, suggesting an extreme biostratinomic bias. By comparison with previously described arthropodan SCFs from the Cambrian of Canada, the Winneshiek fossils extend the geographic, palaeoenvironmental and temporal range of this taphonomic window and provide a complementary tool for reconstructing the diversity and ecology of the Winneshiek biota.

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Copepod Mandible Palynomorphs From the Nolichucky Shale (Cambrian, Tennessee): Implications for the Taphonomy and Recovery of Small Carbonaceous Fossils

Cited by 30 publications

References 38 publications

Phylogenomic analysis of Copepoda (Arthropoda, Crustacea) reveals unexpected similarities with earlier proposed morphological phylogenies

Phylogenomic analysis of Copepoda (Arthropoda, Crustacea) reveals unexpected similarities with earlier proposed morphological phylogenies

Origins and early evolution of arthropods

Exceptionally preserved arthropodan microfossils from the Middle Ordovician Winneshiek Lagerstätte, Iowa, USA

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