Project 1228: J. C. Lamsdell, S. C. McKenzie. 2015. Tachypleus syriacus (Woodward)—a sexually dimorphic Cretaceous crown limulid reveals underestimated horseshoe crab divergence times. Organisms Diversity & Evolution. 15 (4):681-693.
Abstract
The fossil record represents an important test to molecular divergence estimates, with known occurrences representing minimum divergence times for sister taxa. As such, accurately placing fossils in phylogenies is integral to understanding the patterns and processes that shape the tree of life. The chelicerate order Xiphosura comprises classic archetypes of morphological stasis, with the earliest known Ordovician representatives exhibiting all key morphological characteristics of the group. Molecular studies on the four extant species consistently retrieve a basal split between Limulinae and Tachypleinae, but conflict regarding the relationships of the three Asian species. Molecular divergence estimates using either no or a single fossil calibration point infer a Cretaceous or Palaeogene origin for Limulidae and a Palaeogene or Neogene origin for Tachypleinae and Tachypleus. Here, we present male and female specimens of Tachypleus syriacus (=‘Mesolimulus’ syriacus) from the Cretaceous of Lebanon, revealing an anterior scalloped carapace margin in males – a derived condition of sexual dimorphism shared with Tachypleus tridentatus. Morphological phylogenetic analysis of total group Limulidae retrieves a monophyletic Tachypleus with a minimum divergence time during the Cretaceous, while crown-group Tachypleinae and Limulidae are both present during the Triassic, showing that molecular clock analyses have significantly underestimated the divergence times for these taxa.Read the article »
Article DOI: 10.1007/s13127-015-0229-3
Project DOI: 10.7934/P1228, http://dx.doi.org/10.7934/P1228
This project contains | Matrices |
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Download Project SDD File | Total scored cells: 287 Total media associated with cells: 0 Total labels associated with cell media: 0 |
Characters | |
Total characters: 20 Total characters with associated media: 0 Total characters with media with labels: 0 Total character states: 40 Total character states with associated media: 0 Total character states with media with labels:0 Total unordered/ordered characters:20/0 |
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MorphoBank Project 1228
MorphoBank Project 1228
- Creation Date:
22 July 2014 - Publication Date:
03 December 2015 - Project views: 23092
- Matrix downloads: 4
Authors' Institutions
- Yale University
- Mercyhurst University
Members
member name | taxa | specimens | media | chars | character
| cell scorings (scored, NPA, "-") | cell
| rules | ||||||
James Lamsdell Project Administrator | 18 | 1 | 1 | 20 | 0 | 0 | 287 (287, 0, 0) | 0 | 0 | 0 |
Taxonomic Overview for Matrix 'M2794' (18 Taxa)
taxon | unscored cells |
scored cells |
no cell support |
NPA cells |
"-" cells | cell images | labels on cell images |
member access |
[1] † Paleolimulus signatus Last Modified in 07/22/14 | 2 | 18 | 18 | 0 | 0 | 0 | 0 | 1 |
[2] Carcinoscorpius rotundicauda Last Modified in 07/22/14 | 0 | 20 | 20 | 0 | 0 | 0 | 0 | 1 |
[3] † Crenatolimulus paluxyensis Last Modified in 07/22/14 | 6 | 14 | 14 | 0 | 0 | 0 | 0 | 1 |
[4] † Limulitella bronni Last Modified in 07/22/14 | 7 | 13 | 13 | 0 | 0 | 0 | 0 | 1 |
[5] † Limulitella vicensis Last Modified in 07/22/14 | 8 | 12 | 12 | 0 | 0 | 0 | 0 | 1 |
[6] † Limulus coffini Last Modified in 07/22/14 | 11 | 9 | 9 | 0 | 0 | 0 | 0 | 1 |
[7] † Limulus decheni Last Modified in 07/22/14 | 4 | 16 | 16 | 0 | 0 | 0 | 0 | 1 |
[8] Limulus polyphemus Last Modified in 07/22/14 | 0 | 20 | 20 | 0 | 0 | 0 | 0 | 1 |
[9] † Limulus sp. Last Modified in 07/22/14 | 5 | 15 | 15 | 0 | 0 | 0 | 0 | 1 |
[10] † Mesolimulus crespelli Last Modified in 07/22/14 | 6 | 14 | 14 | 0 | 0 | 0 | 0 | 1 |
[11] † Mesolimulus syriacus Last Modified in 07/22/14 | 3 | 17 | 17 | 0 | 0 | 0 | 0 | 1 |
[12] † Mesolimulus walchi Last Modified in 07/22/14 | 2 | 18 | 18 | 0 | 0 | 0 | 0 | 1 |
[13] † Tachypleus gadeai Last Modified in 07/22/14 | 4 | 16 | 16 | 0 | 0 | 0 | 0 | 1 |
[14] Tachypleus gigas Last Modified in 07/22/14 | 0 | 20 | 20 | 0 | 0 | 0 | 0 | 1 |
[15] Tachypleus tridentatus Last Modified in 07/22/14 | 0 | 20 | 20 | 0 | 0 | 0 | 0 | 1 |
[16] † Tarracolimulus rieki Last Modified in 07/22/14 | 6 | 14 | 14 | 0 | 0 | 0 | 0 | 1 |
[17] † Victalimulus mcqueeni Last Modified in 07/22/14 | 3 | 17 | 17 | 0 | 0 | 0 | 0 | 1 |
[18] † Yunnanolimulus luopingensis Last Modified in 07/22/14 | 6 | 14 | 14 | 0 | 0 | 0 | 0 | 1 |
Project views
type | number of views | Individual items viewed (where applicable) |
Total project views | 23092 | |
Project overview | 4687 | |
Media views | 4996 | Media search (4300 views); M336520 (696 views); |
Matrix views | 2168 | Matrix landing page (1921 views); Limulidae (247 views); |
Specimen list | 2449 | |
Bibliography | 1031 | |
Taxon list | 7758 | |
Documents list | 3 |
Project downloads
type | number of downloads | Individual items downloaded (where applicable) |
Total downloads from project | 264 | |
Project downloads | 260 | |
Matrix downloads | 4 | Limulidae (4 downloads); |