Horseshoe crab phylogeny and independent colonizations of fresh water: ecological invasion as a driver for morphological innovation
- J. Lamsdell
- Environmental Science, Geography
- 1 March 2016
A phylogenetic analysis of Xiphosurida is presented and horseshoe crabs are shown to have a more dynamic and complex evolutionary history than previously supposed, with the extant species representing only a fraction of the group's past ecological and morphological diversity.
Revised systematics of Palaeozoic ‘horseshoe crabs’ and the myth of monophyletic Xiphosura
- J. Lamsdell
- Biology
- 2013
A number of other characters, including the form of the chelicerae and appendage VII, indicate that xiphosurans may be paraphyletic with respect to a clade consisting of chasmataspidids, eurypterids, and arachnids.
The ‘Tully monster’ is a vertebrate
A combination of characters, supported by phylogenetic analysis, identifies Tullimonstrum as a vertebrate, and places it on the stem lineage to lampreys (Petromyzontida), increasing the known morphological disparity of extinct lampreys.
Implied weighting and its utility in palaeontological datasets: a study using modelled phylogenetic matrices
- Curtis R. Congreve, J. Lamsdell
- Biology
- 1 May 2016
The results show that implied weighting is inconsistent in its ability to retrieve a known phylogenetic tree, and suggest that equal weights may be a preferable method for parsimony analysis.
Cope's Rule and Romer's theory: patterns of diversity and gigantism in eurypterids and Palaeozoic vertebrates
- J. Lamsdell, S. Braddy
- Environmental Science, GeographyBiology Letters
- 23 April 2010
Analysis of family-level originations and extinctions among eurypterids and Palaeozoic vertebrates show that the diversity of Eurypterina waned during the Devonian, while the Placodermi radiated, yet Stylonurina remained relatively unaffected.
Segmentation and tagmosis in Chelicerata.
- J. Dunlop, J. Lamsdell
- BiologyArthropod structure & development
- 1 May 2017
A new method for quantifying heterochrony in evolutionary lineages
- J. Lamsdell
- BiologyPaleobiology
- 13 May 2020
Heterochronic weighting proves to be an effective method to quantify heterochronic trends within a phylogenetic framework and is readily applicable to any group of organisms that have well-defined morphological characteristics, ontogenetic information, and resolved internal relationships.
All the better to see you with: eyes and claws reveal the evolution of divergent ecological roles in giant pterygotid eurypterids
- V. McCoy, J. Lamsdell, M. Poschmann, Ross P. Anderson, D. Briggs
- Biology, Environmental ScienceBiology Letters
- 1 August 2015
Vision in Erettopterus osiliensis and Slimonia acuminata is more acute than in Acutiramus cummingsi, but not to the same degree as in modern active predators, and the morphology of the chelicerae in these genera suggests a grasping function.
Babes in the wood – a unique window into sea scorpion ontogeny
- J. Lamsdell, P. Selden
- BiologyBMC Evolutionary Biology
- 10 May 2013
The ontogenetic development of the genital appendage supports the hypothesis that the structure is homologous to the endopods of the trunk limbs of other arthropods, and certain characteristics including apparent true direct development suggest a closer affinity to arachnids.
The phylogeny and systematics of Xiphosura
- J. Lamsdell
- BiologyPeerJ
- 4 December 2020
An expanded Xiphosurans phylogeny is presented, comprising 58 xiphosuran species as part of a 158 taxon chelicerate matrix coded for 259 characters, and is the first step in resolving longstanding questions regarding the geographic distribution of the modern horseshoe crab species and whether they truly represent ‘living fossils’.
...
...