Project 5158: J. D. Shackleton. 2005. Skeletal homologies, phylogeny and classification of the earliest asterozoan echinoderms. Journal of Systematic Palaeontology. 3 (1):29-114.
Abstract
A thorough reappraisal of extant and fossil asterozoan plate systems is used to construct working hypotheses of primary plate homologies for Ordovician Asterozoa. Results indicate that inferomarginal ossicles of asteroids, somasteroids and the primitive ophiuroid Phragmactis are likely to be homologous with edrioasteroid marginals. The intermediate virgals and coverplates of somasteroids are identified as modified actinals and the sub-laterals of certain stenurids are axial, here termed podial plates, with laterals in these taxa homologous to true lateral plates and adambulacrals of ophiuroids and asteroids, respectively. The nature of the asterozoan mouth frame is reinvestigated as a result of new study of the mouth frames of key taxa, with a reappraisal of existing developmental and symmetry data. It is argued that primitive asterozoan mouth angle plates were entirely ambulacral and probably not spine-bearing, but that mouth spines evolved in asteroids and ophiuroids either on the existing first ambulacrals or by the superposition of first adambulacrals adoral to first ambulacrals. These new data are used to undertake a cladistic analysis of all known genera of Ordovician asterozoan echinoderms (38 taxa), based on a dataset of 150 morphological characters, rooted on the Middle Cambrian edrioasteroid taxa Stromatocystites and Cambraster. The resulting tree is fully resolved although some deeper branches show poor support. It reveals that Ordovician asteroids form a monophyletic group (defined by the presence of an unpaired auxillary inferomarginal, opposing ambulacrals and blocky abutting adambulacrals) and are a sister group to the remaining asterozoans, including the somasteroids. Somasteroids are monophyletic and, with the primitive taxon Phragmactis, are a sister group to the remaining ophiuroids. The class Ophiuroidea is diagnosed by the near-simultaneous appearance of apomorphies including an interradial disc with highly separated arms and aboral and oral interambulacral longitudinal musculature.Read the article »
Article DOI: 10.1017/S1477201905001525
Project DOI: 10.7934/P5158, http://dx.doi.org/10.7934/P5158
This project contains | Matrices |
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Download Project SDD File | Total scored cells: 4434 Total media associated with cells: 0 Total labels associated with cell media: 0 |
Characters | |
Total characters: 150 Total characters with associated media: 0 Total characters with media with labels: 0 Total character states: 320 Total character states with associated media: 0 Total character states with media with labels:0 Total unordered/ordered characters:150/0 |
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MorphoBank Project 5158
MorphoBank Project 5158
- Creation Date:
27 March 2024 - Publication Date:
27 March 2024 - Project views: 992
Authors' Institutions
- University of Cambridge
Members
member name | taxa | specimens | media | chars | character
| cell scorings (scored, NPA, "-") | cell
| rules | ||||||
Shreya Jariwala Project Administrator | 38 | 9 | 9 | 150 | 0 | 0 | 4434 (4434, 0, 0) | 0 | 0 | 0 |
Taxonomic Overview for Matrix 'M29746' (38 Taxa)
taxon | unscored cells |
scored cells |
no cell support |
NPA cells |
"-" cells | cell images | labels on cell images |
member access |
[1] † Archegonaster Last Modified in 03/27/24 | 23 | 127 | 127 | 0 | 0 | 0 | 0 | 1 |
[2] † Arcophiactis Last Modified in 03/27/24 | 43 | 107 | 107 | 0 | 0 | 0 | 0 | 1 |
[3] Aulactis Last Modified in 03/27/24 | 81 | 69 | 69 | 0 | 0 | 0 | 0 | 1 |
[4] † Baliactis Last Modified in 03/27/24 | 58 | 92 | 92 | 0 | 0 | 0 | 0 | 1 |
[5] † Cnemidactis Last Modified in 03/27/24 | 17 | 133 | 133 | 0 | 0 | 0 | 0 | 1 |
[6] † Chinianaster Last Modified in 03/27/24 | 23 | 127 | 127 | 0 | 0 | 0 | 0 | 1 |
[7] † Drepanaster Last Modified in 03/27/24 | 22 | 128 | 128 | 0 | 0 | 0 | 0 | 1 |
[8] † Encrinaster Last Modified in 03/27/24 | 17 | 133 | 133 | 0 | 0 | 0 | 0 | 1 |
[9] Eophiura Last Modified in 03/27/24 | 28 | 122 | 122 | 0 | 0 | 0 | 0 | 1 |
[10] † Euzonosoma Last Modified in 03/27/24 | 28 | 122 | 122 | 0 | 0 | 0 | 0 | 1 |
[11] † Furcaster Last Modified in 03/27/24 | 35 | 115 | 115 | 0 | 0 | 0 | 0 | 1 |
[12] † Girvanaster Last Modified in 03/27/24 | 17 | 133 | 133 | 0 | 0 | 0 | 0 | 1 |
[13] † Hudsonaster Last Modified in 03/27/24 | 33 | 117 | 117 | 0 | 0 | 0 | 0 | 1 |
[14] † Hypophiura Last Modified in 03/27/24 | 30 | 120 | 120 | 0 | 0 | 0 | 0 | 1 |
[15] † Lanthanaster Last Modified in 03/27/24 | 36 | 114 | 114 | 0 | 0 | 0 | 0 | 1 |
[16] † Lapworthura Last Modified in 03/27/24 | 16 | 134 | 134 | 0 | 0 | 0 | 0 | 1 |
[17] † Mastigactis Last Modified in 03/27/24 | 39 | 111 | 111 | 0 | 0 | 0 | 0 | 1 |
[18] † Ophioxenikos Last Modified in 03/27/24 | 69 | 81 | 81 | 0 | 0 | 0 | 0 | 1 |
[19] † Palaeura Last Modified in 03/27/24 | 20 | 130 | 130 | 0 | 0 | 0 | 0 | 1 |
[20] † Palasterina Last Modified in 03/27/24 | 23 | 127 | 127 | 0 | 0 | 0 | 0 | 1 |
[21] † Petraster Last Modified in 03/27/24 | 28 | 122 | 122 | 0 | 0 | 0 | 0 | 1 |
[22] † Phragmactis Last Modified in 03/27/24 | 25 | 125 | 125 | 0 | 0 | 0 | 0 | 1 |
[23] † Platanaster Last Modified in 03/27/24 | 20 | 130 | 130 | 0 | 0 | 0 | 0 | 1 |
[24] † Pradesura Last Modified in 03/27/24 | 20 | 130 | 130 | 0 | 0 | 0 | 0 | 1 |
[25] † Promopalaeaster Last Modified in 03/27/24 | 40 | 110 | 110 | 0 | 0 | 0 | 0 | 1 |
[26] † Protaster Last Modified in 03/27/24 | 15 | 135 | 135 | 0 | 0 | 0 | 0 | 1 |
[27] Rhopalocoma Last Modified in 03/27/24 | 25 | 125 | 125 | 0 | 0 | 0 | 0 | 1 |
[28] † Schuchertia Last Modified in 03/27/24 | 80 | 70 | 70 | 0 | 0 | 0 | 0 | 1 |
[29] † Siluraster Last Modified in 03/27/24 | 27 | 123 | 123 | 0 | 0 | 0 | 0 | 1 |
[30] † Stenaster Last Modified in 03/27/24 | 25 | 125 | 125 | 0 | 0 | 0 | 0 | 1 |
[31] † Stibaraster Last Modified in 03/27/24 | 33 | 117 | 117 | 0 | 0 | 0 | 0 | 1 |
[32] † Stuertzaster Last Modified in 03/27/24 | 37 | 113 | 113 | 0 | 0 | 0 | 0 | 1 |
[33] † Urasterella Last Modified in 03/27/24 | 39 | 111 | 111 | 0 | 0 | 0 | 0 | 1 |
[34] † Villebrunaster Last Modified in 03/27/24 | 25 | 125 | 125 | 0 | 0 | 0 | 0 | 1 |
[35] † Tribulosaster Last Modified in 03/27/24 | 57 | 93 | 93 | 0 | 0 | 0 | 0 | 1 |
[36] † Thoralaster Last Modified in 03/27/24 | 44 | 106 | 106 | 0 | 0 | 0 | 0 | 1 |
[37] † Cambraster Last Modified in 03/27/24 | 37 | 113 | 113 | 0 | 0 | 0 | 0 | 1 |
[38] † Stromatocystites Last Modified in 03/27/24 | 31 | 119 | 119 | 0 | 0 | 0 | 0 | 1 |
Project views
type | number of views | Individual items viewed (where applicable) |
Total project views | 992 | |
Matrix views | 37 | Matrix landing page (32 views); Dean 2005 (5 views); |
Project overview | 40 | |
Media views | 272 | Media search (113 views); M902737 (16 views); M902736 (19 views); M902735 (17 views); M902734 (17 views); M902733 (19 views); M902732 (17 views); M902731 (19 views); M902730 (18 views); M902729 (17 views); |
Documents list | 36 | |
Bibliography | 29 | |
Views for media list | 38 | |
Specimen list | 231 | |
Taxon list | 309 |