Part T, Echinodermata 2, vol. 1-3, Complete Volume

Ubaghs, Georges; Rasmussen, Hjalte; Meyer, David L.; Macurda, Donald B.; Fay, Robert O.; Peck, R. E.; Sprinkle, James; Breimer, Albert; Jeffords, Russell M.; Sieverts-Doreck, Hertha; Moore, Raymond C.; Brower, James C.; Strimple, H. L.; Lane, N. Gary; Robison, R. A.; Roux, Michel

doi:10.17161/dt.v0i0.5651

Cited by 2 publications

(4 citation statements)

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“…This reflects: (1) the general need for collection by deepwater trawl, dredge, or submersible vehicle, (2) the relative rarity of undamaged specimens, and (3) the common use of formalin to fix marine specimens. Yet because crinoid systematics has been predominantly based on the morphology of fossils (Ubaghs et al 1978), it is in need of a molecular dimension; the development of a phylogenetic basis for classification is a recognized challenge (Ausich and Kammer 2001). In this paper we report and analyse a morphological character-state matrix, and nuclear and mitochondrial gene sequences from a small, but fairly representative, taxon sample that includes rarely collected Mesozoic "living fossils".…”

Section: Introductionmentioning

confidence: 99%

Crinoid phylogeny: a preliminary analysis (Echinodermata: Crinoidea)

et al. 2003

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We describe the first molecular and morphological analysis of extant crinoid highlevel inter-relationships. Nuclear and mitochondrial gene sequences and a cladistically coded matrix of 30 morphological characters are presented, and analysed by phylogenetic methods.The molecular data were compiled from concatenated nuclear-encoded 18S rDNA, internal transcribed spacer 1, 5.8S rDNA, and internal transcribed spacer 2, together with part of mitochondrial 16S rDNA, and comprised 3593 sites, of which 313 were parsimonyinformative. The molecular and morphological analyses include data from the bourgueticrinid, Bathycrinus; the antedonid comatulids, Dorometra and Florometra; the cyrtocrinids Cyathidium, Gymnocrinus, and Holopus; the isocrinids Endoxocrinus, and two species of Metacrinus; as well as from Guillecrinus and Caledonicrinus, whose ordinal relationships are uncertain, together with morphological data from Proisocrinus. Because the molecular data include indel-rich regions, special attention was given to alignment procedure, and it was found that relatively low, gene-specific, gap penalties gave alignments from which congruent phylogenetic information was obtained from both well-aligned, indel-poor and potentially misaligned, indel-rich regions. The different sequence data partitions also gave essentially congruent results. The overall direction of evolution in the gene trees remains uncertain: an asteroid outgroup places the root on the branch adjacent to the slowly-evolving isocrinids (consistent with palaeontological order of first appearances), but maximum likelihood analysis with a molecular clock places it elsewhere. Despite lineage-specific rate differences, the clock Only an unusual, divergent 18S rDNA sequence was obtained from the morphologically strange cyrtocrinid Cyathidium. Although not analysed in detail, features of this sequence suggested that it may be a PCR artefact, so that the apparenly basal position of this taxon requires confirmation. If not an artefact, Cyathidium either diverged from the crinoid stem much earlier than has been reognized hitherto (i.e., it may be a Palaeozoic relic), or it has an atypically high rate of molecular evolution.

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Section: Introductionmentioning

confidence: 99%

Crinoid phylogeny: a preliminary analysis (Echinodermata: Crinoidea)

et al. 2003

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“…200 mm: Ubaghs et al . 1978; Guensburg & Sprinkle 2003) were only slightly taller than the eocrinoids (e.g. Rhipidocystis and Rhopalocystis ) they co‐existed with, and the Early Ordovician crinoid Trichinocrinus was probably much shorter than the shortest ( c .…”

Section: Resultsmentioning

confidence: 99%

“…2017), the early crinoid Aethocrinus with its unique Hohlwurzel holdfast (Ubaghs et al . 1978), and the rhombiferan Macrocystella with its distinctive stem that was probably used more for stability in soft substrates than for permanent attachment (Paul 1968; Mergl & Prokop 2006; Dornbos 2006).…”

Section: Resultsmentioning

confidence: 99%

“…Most unusual among these ‘raptors’ are the crinoids Euspirocrinus (Ubaghs et al . 1978; Brett 1984) and Protaxocrinus (Meyer & Lane 1976; Ausich 1978), whose stout, ramous and nonpinnulate arms cause them to be considered microcarnivores, a specialized but generally rare crinoid feeding strategy maintained throughout the Palaeozoic for numerous cyathocrin, sagenocrinid and taxocrinid crinoids (Meyer & Lane 1976; Brett 1984). However, raptorial habits account for only 5% of Ordovician feeding strategies.…”

Section: Resultsmentioning

confidence: 99%

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Ecological novelty at the start of the Cambrian and Ordovician radiations of echinoderms

Novack‐Gottshall,

Purcell,

Sultan

et al. 2024

Palaeontology

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The Cambrian and Ordovician radiations marked the origins of all major echinoderm clades and established their Phanerozoic ecological blueprint. Recent claims of modest innovation of early echinoderms and other animals suggest constraints on novelty during the origins of phyla. Here, we document the life‐habit richness, body size, tiering, habitat usage, mobility, diet and foraging habits of 366 Cambrian–Ordovician echinoderm genera across a time‐scaled phylogeny to identify the timing and impact of novelty. Most early echinoderms were sedentary, filter‐feeding microbivores, and their body sizes, diets and modes of locomotion were largely unchanged through time, despite major volatility in taxonomic composition. Cambrian echinoderms lived close to the seafloor, with stylophorans first evolving semi‐infaunality. Many Ordovician echinoderms lived farther from the seafloor, with more complex filter‐feeding organs and tiering structure, often using other organisms as substrates. Mobile carnivores and mass‐feeders emerge then, too, across diverse asterozoans and echinozoans. Most of these novelties coincide with the origins of individual clades during the early and late Cambrian (Terreneuvian/Series 2 and Furongian), and 10–20 million years pass before most become ecologically important. Life‐habit evolution within most taxa involved new variations in these traits, with crinoids and asterozoans better able to shift strategies. The Ordovician radiation records more new variability in pre‐existing Cambrian life habits rather than radical re‐invention, with important novelties (like mobile carnivory and mass‐feeding, increased height off the seafloor, and biotic substrates) becoming ecologically more impactful. Taxa with these strategies were those best able to capitalize on the newly heterogeneous Ordovician world.

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Part T, Echinodermata 2, vol. 1-3, Complete Volume

Cited by 2 publications

References 0 publications

Crinoid phylogeny: a preliminary analysis (Echinodermata: Crinoidea)

Crinoid phylogeny: a preliminary analysis (Echinodermata: Crinoidea)

Ecological novelty at the start of the Cambrian and Ordovician radiations of echinoderms

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