Pennsylvanian (Late Carboniferous) Echinoids From the Winchell Formation, North-Central Texas, Usa

Schneider, Chris L.; Sprinkle, James; Ryder, D.M.

doi:10.1666/0022-3360(2005)079[0745:plceft]2.0.co;2

Cited by 19 publications

(34 citation statements)

References 11 publications

(5 reference statements)

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“…As outgroup we used the Carboniferous genus Archaeocidaris (Archaeocidaridae). This is an unambiguous late stem-group member, and its morphology is well documented thanks to two recent studies of spectacularly well-preserved individuals (Lewis & Ensom 1982;Schneider et al 2005).…”

Section: Choice Of Taxamentioning

confidence: 78%

The phylogeny and classification of post-Palaeozoic echinoids

Kroh

Smith

2010

Journal of Systematic Palaeontology

289

367

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The relationships of post-Palaeozoic echinoids at family level are established through phylogenetic analysis of 169 taxa and 306 skeletal characters (excluding pedicellariae). Previous phylogenetic analyses of echinoids have either examined specific subgroups in detail or have looked at a relatively small number of taxa selected from across the class, with sparse sampling potentially affecting the reliability of results adversely. Our new analyses represent a compromise between encompassing the diversity of form that exists, while keeping the number of taxa to a level that does not make rigorous analysis impossibly time-consuming. In constructing the taxon-character data matrix we have encountered a surprising lack of primary data on plating pattern, lantern, and girdle structure for many supposedly "well-known" taxa. A well-resolved phylogenetic hypothesis was obtained and is used as the basis for a formal classification. Characters generally have a high retention index (>0.7) but low consistency index (<0.25) suggesting that, although characters are largely retained after they first evolve, most also undergo occasional reversal or convergence. Although parts of the resulting trees are only weakly supported (e.g. the precise sister group of the Irregularia), other parts are unambiguously resolved. Not unexpectedly, deep nodes are often not supported by unique apomorphies and higher taxa acquire their characteristic set of features over time. Diagnoses based on crown group taxa thus often fail to encompass fossil stem-group members adequately. Establishing the relationships of taxa at the root of large groups is hampered by limited character resolution. The influence of fossil taxa on the topology was explored by comparing the tree topologies obtained with and without their inclusion. We show that removal of fossils from stem groups makes no difference where their crown group is morphologically conservative, but has a major influence where extant sister groups are separated by large morphological gaps. Completeness of the echinoid record and its match to the stratigraphical record of first occurrences is tested using various metrics and found to be highly congruent, with irregular echinoids showing a higher congruence than regular ones.

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Section: Choice Of Taxamentioning

confidence: 78%

The phylogeny and classification of post-Palaeozoic echinoids

Kroh

Smith

2010

Journal of Systematic Palaeontology

289

367

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“…Others ending in large clavate bulb covered in spinules. It is likely that spines varied aborally to orally, as is present in some archaeocidarids 22 and recent cidaroids such as Eucidaris clavata 33 . Although this variability exists, all spines of differing morphologies contain diagonally oriented ridge bearing first row of spinules.…”

Section: Systematic Palaeontologymentioning

confidence: 99%

“…Most Palaeozoic echinoids had poor preservation potential compared to post-Palaeozoic forms, with many clades displaying imbricate, overlapping, plating which presumably lacked stereomic interlocking 20 21 . Because of this non-rigid test plating, Palaeozoic echinoids presumably disarticulated rapidly following their death, and thus well-preserved specimens in the Palaeozoic are usually limited to Lagerstätte deposits 22 . The stem-group cidaroid herein described from the Guadalupian of Texas, Eotiaris guadalupensis n.…”

mentioning

confidence: 99%

Reorganization of sea urchin gene regulatory networks at least 268 million years ago as revealed by oldest fossil cidaroid echinoid

Thompson

Petsios

Davidson

et al. 2015

Sci Rep

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Echinoids, or sea urchins, are rare in the Palaeozoic fossil record, and thus the details regarding the early diversification of crown group echinoids are unclear. Here we report on the earliest probable crown group echinoid from the fossil record, recovered from Permian (Roadian-Capitanian) rocks of west Texas, which has important implications for the timing of the divergence of crown group echinoids. The presence of apophyses and rigidly sutured interambulacral areas with two columns of plates indicates this species is a cidaroid echinoid. The species, Eotiaris guadalupensis, n. sp. is therefore the earliest stem group cidaroid. The occurrence of this species in Roadian strata pushes back the divergence of cidaroids and euechinoids, the clades that comprise all living echinoids, to at least 268.8 Ma, ten million years older than the previously oldest known cidaroid. Furthermore, the genomic regulation of development in echinoids is amongst the best known, and this new species informs the timing of large-scale reorganization in echinoid gene regulatory networks that occurred at the cidaroid-euechinoid divergence, indicating that these changes took place by the Roadian stage of the Permian.

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“…Pedicellarial types, if present in species other than the type of the genus, were scored irrespective of whether they were found in the type species or not. As outgroup we used the late Palaeozoic fossil Archaeocidaris, known from two very well preserved species with spines and pedicellariae (Lewis and Ensom 1982;Schneider et al 2005). Appendix 1 lists the characters and their states and provides the pedicellarial character scores for the 76 taxa.…”

Section: Tree Constructionmentioning

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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Pennsylvanian (Late Carboniferous) Echinoids From the Winchell Formation, North-Central Texas, Usa

Cited by 19 publications

References 11 publications

The phylogeny and classification of post-Palaeozoic echinoids

The phylogeny and classification of post-Palaeozoic echinoids

Reorganization of sea urchin gene regulatory networks at least 268 million years ago as revealed by oldest fossil cidaroid echinoid

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

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