Lampraspis carmani ( Denison, 1960 )

Randle, Emma & Sansom, Robert S., 2017, Exploring phylogenetic relationships of Pteraspidiformes heterostracans (stem-gnathostomes) using continuous and discrete characters, Journal of Systematic Palaeontology 15 (7), pp. 583-599 : 596

Lampraspis carmani ( Denison, 1960)

1960 Pteraspis carmani Denison : 568, figs 124 — 141.

1984 Zascinaspis carmani (Denison) Blieck : 61.

Diagnosis. As for ‘ Pteraspis’ carmani in Denison (1960).

Remarks. Phylogenetic analyses placed Zascinaspis heintzi and Z. carmani at different places in the tree ( Figs 4 — 6 ), indicating they do not belong within the same genus. Blieck (1984) assigned ‘ P.’ carmani to Zascinaspis due to similarities in the proportions of the rostral and dorsal plates and the orbito-pineal belt, as well as shared oral region arrangement. In our analysis, ‘ Z.’ carmani falls within the Protaspididae as sister taxon to Lampraspis (both recovered from western USA localities). Lampraspis carmani also shares with protaspids an ornamentation of undulating ridges and a branchial opening placed towards the posterior end of the dorsal plate, with reduced cornual plates.

Figures

Figure 4. Results from the phylogenetic analysis using discrete data only. A, strict consensus of 275 most parsimonious trees with equal character weights; length 276 steps, consistency index (CI) = 0.35, retention index (RI) = 0.59, and rescaled consistency index (RC) = 0.22. B, strict consensus of four most parsimonious trees with implied character weighting (k = 3) (tree length 23.11). Psammosteidae taxa in bold.

Figure 5. Phylogenetic results from data sets containing discrete (1—64) and continuous (66, 68, 70, 72, 77, 80, 82, 86) characters. A, most parsimonious tree with equally weighted characters (tree length 319.36). B, most parsimonious tree with implied weighting (k = 3) (tree length 26.53). Psammosteidae taxa in bold (for which quantitative characters have been treated as inapplicable, i.e. nonhomologous).

Figure 6. Most parsimonious result from a phylogenetic analysis of discrete (1—64) and discretized continuous characters identified through gap coding (88—100). A, strict consensus of 30 most parsimonious trees with equally weighted characters (tree length 346). B, most parsimonious solution with implied weighted characters (k = 3) (tree length 27.86). Psammosteidae taxa in bold (for which quantitative characters have been treated as inapplicable, i.e. non-homologous).