Bromidechinus, a new Ordovician echinozoan (Echinodermata), and its bearing on the early history of echinoids

Smith, Andrew B.; Savill, Jeremy J.

doi:10.1017/s0263593300000109

Cited by 27 publications

(17 citation statements)

References 5 publications

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“…Surprisingly little is known about the evolutionary history of echinoid pedicellariae, and the fossil record provides relatively few clues. While the first pedicellariae are recorded from the late Ordovician (Nestler 1970), shortly after the earliest records of echinoid tests (Smith and Savill 2002), the small size and fragility of pedicellariae has meant that they are rarely preserved and even more rarely described. Furthermore, those few studies that have described pedicellariae are usually based on material found in sieved sediment samples that cannot be assigned to particular taxa with any degree of confidence (e.g.…”

Section: Introductionmentioning

confidence: 99%

The evolution of pedicellariae in echinoids: an arms race against pests and parasites

Coppard¹,

Kroh²,

Smith³

2010

Acta Zoologica

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Coppard, S.E., Kroh, A. and Smith, A.B. (2010). The evolution of pedicellariae in echinoids: an arms race against pests and parasites. —Acta Zoologica (Stockholm) 00:1–24. Sea urchins (Echinoidea) have evolved a diverse array of jawed appendages termed pedicellariae to deter pests and predators. Pedicellarial structure and function are reviewed and their distribution mapped in 75 extant genera. Using a phylogeny of echinoids at family level constructed from 353 skeletal characters scored across 162 extant and fossil taxa, the evolution of pedicellarial form and function is reconstructed. For much of the Palaeozoic echinoids possessed a very restricted pedicellarial armament. By the early Mesozoic a diverse array of pedicellarial types had become established, implying that the threat from predators and pests markedly increased at this time. Since the Triassic, echinoids have continued to improve their defensive capability by evolving more effective venom delivery in globiferous pedicellariae, developing spatulate‐tips and curved blades for a more efficient grab in tridentate pedicellariae, and stouter, more robust valves with a stronger bite in ophicephalous pedicellariae to disable and remove ectoparasites. However, pedicellarial types are shown to be particularly prone to subsequent secondary loss, especially among infaunal echinoids, and thus have higher homoplasy levels than other phylogenetically useful skeletal structures.

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Section: Introductionmentioning

confidence: 99%

The evolution of pedicellariae in echinoids: an arms race against pests and parasites

Coppard¹,

Kroh²,

Smith³

2010

Acta Zoologica

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“…Research on the early embryonic development of echinoids has revealed the regulatory interactions that compose the circuitry of developmental GRNs driving early development of the purple sea urchin Strongylocentrotus purpuratus (14). Importantly, echinoids also have an excellent fossil record that dates back to Ordovician strata, more than 400 Mya (17). The combination of a robust fossil record and detailed understanding of the early developmental GRNs in numerous species makes echinoids an opportune group in which to implement integrated approaches to understanding GRN evolution.…”

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confidence: 99%

Paleogenomics of echinoids reveals an ancient origin for the double-negative specification of micromeres in sea urchins

Thompson

Erkenbrack

Hinman

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Establishing a timeline for the evolution of novelties is a common, unifying goal at the intersection of evolutionary and developmental biology. Analyses of gene regulatory networks (GRNs) provide the ability to understand the underlying genetic and developmental mechanisms responsible for the origin of morphological structures both in the development of an individual and across entire evolutionary lineages. Accurately dating GRN novelties, thereby establishing a timeline for GRN evolution, is necessary to answer questions about the rate at which GRNs and their subcircuits evolve, and to tie their evolution to paleoenvironmental and paleoecological changes. Paleogenomics unites the fossil record and all aspects of deep time, with modern genomics and developmental biology to understand the evolution of genomes in evolutionary time. Recent work on the regulatory genomic basis of development in cidaroid echinoids, sand dollars, heart urchins, and other nonmodel echinoderms provides an ideal dataset with which to explore GRN evolution in a comparative framework. Using divergence time estimation and ancestral state reconstructions, we have determined the age of the double-negative gate (DNG), the subcircuit which specifies micromeres and skeletogenic cells in Strongylocentrotus purpuratus. We have determined that the DNG has likely been used for euechinoid echinoid micromere specification since at least the Late Triassic. The innovation of the DNG thus predates the burst of post-Paleozoic echinoid morphological diversification that began in the Early Jurassic. Paleogenomics has wide applicability for the integration of deep time and molecular developmental data, and has wide utility in rigorously establishing timelines for GRN evolution.evolution | evo-devo | euechinoid | cidaroid | gene regulatory networks

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“…Echinozoans possibly appeared and diversified in Baltica during the Middle Ordovician, before spreading to Laurentia in Late Ordovician times (Reich 1999;Smith & Savill 2001;Lefebvre et al 2013). Baltica has yielded the oldest known occurrences of echinoids (Darriwilian; Bockelie & Briskeby 1980;Pisera 1994), holothurians (Darriwilian; Reich 2010) and ophiocistioids (Dapingian; Reich 2001;Rozhnov 2005;Reich & Smith 2009).…”

Section: Bolboporites As An Infrabasal Conementioning

confidence: 99%

Reinterpretation of the enigmatic Ordovician genus Bolboporites (Echinodermata)

et al. 2019

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Bolboporites is an enigmatic Ordovician cone-shaped fossil, the precise nature and systematic affinities of which have been controversial over almost two centuries. For the first time, a wide range of techniques (CT-scan, SEM, cathodoluminescence, XPL, UV epifluorescence, EBSD, FT-IR and XRF spectrometry) were applied to well-preserved specimens of Bolboporites from Norway and Russia. Our main finding confirms its echinoderm affinities, as shown by its stereomic microstructure and by the first definitive evidence of its monocrystalline nature. Each cone consists in a single, microporous calcitic crystal with a narrow longitudinal internal canal. These results are combined with all previous data on Bolboporites to critically discuss five alternative interpretations of this fossil, namely theca, basal cone, spine, columnal, and holdfast, respectively. The most parsimonious scenario considers Bolboporites as an isolated spine, which was articulated in life by a short biserial appendage to the body wall of an unknown echinoderm, possibly of echinozoan affinities.

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Bromidechinus, a new Ordovician echinozoan (Echinodermata), and its bearing on the early history of echinoids

Cited by 27 publications

References 5 publications

The evolution of pedicellariae in echinoids: an arms race against pests and parasites

The evolution of pedicellariae in echinoids: an arms race against pests and parasites

Paleogenomics of echinoids reveals an ancient origin for the double-negative specification of micromeres in sea urchins

<p class="HeadingRunIn"><strong>Reinterpretation of the enigmatic Ordovician genus <em>Bolboporites </em>(Echinodermata)</strong></p>

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