Morphobank

Project 4796: T. J. Cotton, R. A. Fortey. 2005. Comparative morphology and relationships of the Agnostida. Crustacea and Arthropod Relationships. 16:95-136.

Specimen: † Acidiscus birdi (unvouchered)
View: Whole Specimen

More images »

Abstract

The relationships of the agnostid trilobites have been controversial. They have been claimed as highly derived, neotenously-derived trilobites on the one hand, or as arthropods close to the stem group of crustaceans on the other. On the former view, their distinctive autapomorphies are regarded as specialisations related to their mode of life; on the latter, emphasis is placed on the differences from polymerid trilobites as indicating a separated erivation. We consider it necessary to include Eodiscina in any assessment of agnostid relationships. Previously suggested synapomorphies uniting crustaceans and agnostids to the exclusion of trilobites are reviewed, and the majority is rejected. A number of new synapomorphies uniting agnostids with all, or some eodiscinids are described. These characters are tested in the context of a cladistic analysis of 79 eodiscinid and 3 agnostid taxa. We conclude that agnostids are deeply nested within the eodiscinids. The eodiscinid family Weymouthiidae is strongly supported as sister taxon to the Agnostina. Several supposed agnostid autapomorphies are found to be synapomorphies shared with one or more eodiscinid group. At least as far as exoskeletal characters are concerned, the supposed distinctiveness of agnostids has been over-emphasised. To assert non-trilobite relationships of agnostids would require implausible levels of homoplasy.

Read the article »

Article DOI: 10.1201/9781420037548.ch5

Project DOI: 10.7934/P4796, http://dx.doi.org/10.7934/P4796

This project contains	Matrices
6 Media 1 Matrix 1 Document 85 Taxa 6 Specimens 123 Characters Total size of project's media files: 38.84M Download Project SDD File	Total scored cells: 9985 Total media associated with cells: 0 Total labels associated with cell media: 0
	Characters
	Total characters: 123 Total characters with associated media: 0 Total characters with media with labels: 0 Total character states: 299 Total character states with associated media: 0 Total character states with media with labels:0 Total unordered/ordered characters:123/0

Currently Viewing:
MorphoBank Project 4796

Creation Date:
31 July 2023
Publication Date:
01 August 2023
Media downloads: 1

Authors' Institutions

Natural History Museum, London

Members

Shreya Jariwala
Project Administrator

123

9985
(8194, 0, 1791)

Taxonomic Overview for Matrix 'M29403' (85 Taxa)

taxon	unscored cells	scored cells	no cell support	NPA cells	"-" cells	cell images	labels on cell images	member access
[1] † Abakolia minutus Taxon name last Modified on 07/31/23	2	101	98	0	23	0	0	1
[2] † Abakolia pauca Taxon name last Modified on 07/31/23	10	97	90	0	23	0	0	1
[3] † Acidiscus birdi Taxon name last Modified on 07/31/23	8	96	94	0	21	0	0	1
[4] † Acidiscus theristes Taxon name last Modified on 07/31/23	3	105	101	0	19	0	0	1
[5] † Acimetopus bilobatus Taxon name last Modified on 07/31/23	8	92	91	0	24	0	0	1
[6] † Alaskadiscus spinosus Taxon name last Modified on 07/31/23	2	107	104	0	17	0	0	1
[7] † Analox bipunctata Taxon name last Modified on 07/31/23	12	86	83	0	28	0	0	1
[8] † Bathydiscus dolichometopus Taxon name last Modified on 07/31/23	9	89	86	0	28	0	0	1
[9] † Bolboparia superba Taxon name last Modified on 07/31/23	12	94	93	0	18	0	0	1
[10] † Calodiscus lobatus Taxon name last Modified on 07/31/23	8	103	95	0	20	0	0	1
[11] † Cephalopyge notabilis Taxon name last Modified on 07/31/23	9	87	84	0	30	0	0	1
[12] † Chelediscus acifer Taxon name last Modified on 07/31/23	0	99	97	0	26	0	0	1
[13] † Chelediscus chathamensis Taxon name last Modified on 07/31/23	14	87	84	0	25	0	0	1
[14] † Cobboldites comleyensis Taxon name last Modified on 07/31/23	9	86	84	0	30	0	0	1
[15] † Cobboldites itsariensis Taxon name last Modified on 07/31/23	10	88	82	0	31	0	0	1
[16] † Dawsonia bohemicus Taxon name last Modified on 07/31/23	6	94	92	0	25	0	0	1
[17] † Dawsonia dawsoni Taxon name last Modified on 07/31/23	2	97	95	0	26	0	0	1
[18] † Delgadella caudatus Taxon name last Modified on 07/31/23	9	95	91	0	23	0	0	1
[19] † Delgadella lenaicus Taxon name last Modified on 07/31/23	2	98	97	0	24	0	0	1
[20] † Delgadella amouslekensis Taxon name last Modified on 07/31/23	16	86	84	0	23	0	0	1
[21] † Dicerodiscus tsunyiensis Taxon name last Modified on 07/31/23	19	86	84	0	20	0	0	1
[22] † Egyngolia willochra Taxon name last Modified on 07/31/23	9	104	100	0	14	0	0	1
[23] † Egyngolia obtusa Taxon name last Modified on 07/31/23	4	109	102	0	17	0	0	1
[24] † Egyngolia zaicevi Taxon name last Modified on 07/31/23	45	59	57	0	21	0	0	1
[25] † Ekwipagetia marginata Taxon name last Modified on 07/31/23	9	106	100	0	14	0	0	1
[26] † Ekwipagetia plicofimbria Taxon name last Modified on 07/31/23	8	105	100	0	15	0	0	1
[27] † Eodiscus borealis Taxon name last Modified on 07/31/23	3	100	96	0	24	0	0	1
[28] † Eodiscus scanicus Taxon name last Modified on 07/31/23	2	108	98	0	23	0	0	1
[29] † Hebediscina sardoa Taxon name last Modified on 07/31/23	8	104	99	0	16	0	0	1
[30] † Hebediscina blagonravovi Taxon name last Modified on 07/31/23	16	97	90	0	16	0	0	1
[31] † Hebediscina yuqingensis Taxon name last Modified on 07/31/23	12	104	99	0	12	0	0	1
[32] † Hebediscus attleborensis Taxon name last Modified on 07/31/23	16	86	84	0	23	0	0	1
[33] † Helepagetia bitruncula Taxon name last Modified on 07/31/23	8	107	101	0	14	0	0	1
[34] † Jinghediscus nummularius Taxon name last Modified on 07/31/23	11	93	89	0	23	0	0	1
[35] † Kiskinella cristata Taxon name last Modified on 07/31/23	11	99	98	0	14	0	0	1
[36] † Korobovia ocellata Taxon name last Modified on 07/31/23	8	97	94	0	21	0	0	1
[37] † Lenadiscus unicus Taxon name last Modified on 07/31/23	15	96	91	0	16	0	0	1
[38] † Leptochilodiscus punctulatus Taxon name last Modified on 07/31/23	8	89	85	0	30	0	0	1
[39] † Leptochilodiscus succinctus Taxon name last Modified on 07/31/23	1	100	95	0	27	0	0	1
[40] † Litometopus longispinus Taxon name last Modified on 07/31/23	9	87	86	0	28	0	0	1
[41] † Luvsanodiscus gammatus Taxon name last Modified on 07/31/23	0	104	101	0	22	0	0	1
[42] † Macannaia maladensis Taxon name last Modified on 07/31/23	1	115	110	0	12	0	0	1
[43] † Mallagnostus desideratus Taxon name last Modified on 07/31/23	47	53	52	0	24	0	0	1
[44] † Mallagnostus limbatus Taxon name last Modified on 07/31/23	8	87	84	0	31	0	0	1
[45] † Mallagnostus llarenai Taxon name last Modified on 07/31/23	6	96	91	0	26	0	0	1
[46] † Meniscuchus menetus Taxon name last Modified on 07/31/23	8	92	88	0	27	0	0	1
[47] † Meniscuchus nanus Taxon name last Modified on 07/31/23	12	85	84	0	27	0	0	1
[48] † Natalina incita Taxon name last Modified on 07/31/23	15	96	90	0	18	0	0	1
[49] † Natalina dilata Taxon name last Modified on 07/31/23	20	89	86	0	17	0	0	1
[50] † Neocobboldia dentata Taxon name last Modified on 07/31/23	3	99	97	0	23	0	0	1
[51] † Neopagetina rjonsnitzkii Taxon name last Modified on 07/31/23	9	104	101	0	13	0	0	1
[52] † Ninadiscus strobulatus Taxon name last Modified on 07/31/23	12	94	89	0	22	0	0	1
[53] † Oodiscus subgranulatus Taxon name last Modified on 07/31/23	10	88	87	0	26	0	0	1
[54] † Opsidiscus bilobatus Taxon name last Modified on 07/31/23	12	102	95	0	16	0	0	1
[55] † Opsidiscus microspinus Taxon name last Modified on 07/31/23	1	112	107	0	15	0	0	1
[56] † Opsidiscus longispinus Taxon name last Modified on 07/31/23	40	71	69	0	14	0	0	1
[57] † Pagetia bootes Taxon name last Modified on 07/31/23	1	111	109	0	13	0	0	1
[58] † Pagetia prolata Taxon name last Modified on 07/31/23	1	113	110	0	12	0	0	1
[59] † Pagetides elegans Taxon name last Modified on 07/31/23	1	115	109	0	13	0	0	1
[60] † Pagetides fragum Taxon name last Modified on 07/31/23	8	106	101	0	14	0	0	1
[61] † Pseudocobboldia pulchra Taxon name last Modified on 07/31/23	10	97	93	0	20	0	0	1
[62] † Runcinodiscus index Taxon name last Modified on 07/31/23	8	93	91	0	24	0	0	1
[63] † Semadiscus sollennis Taxon name last Modified on 07/31/23	40	59	58	0	25	0	0	1
[64] † Serrodiscus speciosus Taxon name last Modified on 07/31/23	1	103	98	0	24	0	0	1
[65] † Serrodiscus gravestocki Taxon name last Modified on 07/31/23	11	95	91	0	21	0	0	1
[66] † Serrodiscus daedalus Taxon name last Modified on 07/31/23	10	95	91	0	22	0	0	1
[67] † Serrodiscus ctenoa Taxon name last Modified on 07/31/23	0	101	98	0	25	0	0	1
[68] † Sinodiscus shipaiensis Taxon name last Modified on 07/31/23	0	103	101	0	22	0	0	1
[69] † Sinodiscus subquadratus Taxon name last Modified on 07/31/23	8	98	94	0	21	0	0	1
[70] † Sinopagetia jinnanensis Taxon name last Modified on 07/31/23	10	97	96	0	17	0	0	1
[71] † Stigmadiscus stenometopus Taxon name last Modified on 07/31/23	15	86	84	0	24	0	0	1
[72] † Tannudiscus altus Taxon name last Modified on 07/31/23	10	89	83	0	30	0	0	1
[73] † Tannudiscus balanus Taxon name last Modified on 07/31/23	0	97	94	0	29	0	0	1
[74] † Tchernyshevioides ninae Taxon name last Modified on 07/31/23	8	99	96	0	19	0	0	1
[75] † Tsunyidiscus niutitangensis Taxon name last Modified on 07/31/23	1	112	109	0	13	0	0	1
[76] † Tsunyidiscus kaiyangensis Taxon name last Modified on 07/31/23	5	112	106	0	12	0	0	1
[77] † Tsunyidiscus aclis Taxon name last Modified on 07/31/23	9	107	103	0	11	0	0	1
[78] † Tsunyidiscus orientalis Taxon name last Modified on 07/31/23	1	108	104	0	18	0	0	1
[79] † Tsunyidiscus longquanensis Taxon name last Modified on 07/31/23	0	107	104	0	19	0	0	1
[80] † Weymouthia nobilis Taxon name last Modified on 07/31/23	27	74	72	0	24	0	0	1
[81] † Yukonia intermedia Taxon name last Modified on 07/31/23	1	112	105	0	17	0	0	1
[82] † Yukonides lacrinus Taxon name last Modified on 07/31/23	9	105	98	0	16	0	0	1
[83] † Condylopyge amitina Taxon name last Modified on 07/31/23	2	96	94	0	27	0	0	1
[84] † Peronopsis roddyi Taxon name last Modified on 07/31/23	2	95	92	0	29	0	0	1
[85] † Ptychagnostus gibbus Taxon name last Modified on 07/31/23	1	99	97	0	25	0	0	1

Project downloads

type	number of downloads	Individual items downloaded (where applicable)
Total downloads from project	1
Media downloads	1	M890505 (1 download);