Reply to Comment on: Álvaro J.J., Esteve, J. & Zamora, S. 2019. Morphological assessment of the earliest paradoxidid trilobites (Cambrian Series 3) from Morocco and Spain [Geological Magazine] by Geyer G, Nowicki J, Żylińska A & Landing E

Abstract

Two research teams have different opinions regarding the number of paradoxidine species close to the base of the Miaolingian in Morocco and Spain. Geyer & Vincent (2015) recognized five species based on a mosaic of overlapping characters that include some relative length and width ratios, qualitative descriptions of cranidial and pygidial outlines, and relief observations. In contrast, Álvaro et al. (2018) conducted a morphometric analysis of all these specimens from the Cambropallas telesto acme level of the Assemame quarry and concluded that the Moroccan material had been taxonomically over-split and was represented by only two species, Acadoparadoxides mureroensis and A. nobilis. Subsequently, Geyer et al. (2019) commented that we had not analysed some diagnostic characters, and applied the stratigraphic setting of their morphospecies as a diagnostic character for taxonomic identification. After sampling the Cambropallas telesto acme level in the Taroucht quarry, where the other team purchased its collection, and re-analysing the diagnostic characters claimed by Geyer et al. (2019), our conclusions are maintained: (i) morphometric values of several paratype specimens fall outside the purported ranges of diagnostic characters; (ii) all 2D morphometric analyses incorporating the diagnostic characters of the morphospecies are unable to detect interspecific differences, except for A. nobilis; and (iii) the slight concavity displayed by some pygidia, strongly controlled by preservation, is in need of 3D biometrical analysis. Hence, our proposed synonymy should be maintained until 3D statistical analyses are available on material preserved in carbonate or concretions.

Insufficient Evidence for Multiple Species of Tyrannosaurus in the Latest Cretaceous of North America: A Comment on “The Tyrant Lizard King, Queen and Emperor: Multiple Lines of Morphological and Stratigraphic Evidence Support Subtle Evolution and Probable Speciation Within the North American Genus Tyrannosaurus”

“…It remains to be established if the diagnostic characters, as set out by the authors, are invariant throughout growth; if they are invariant then their case for multiple species might be strengthened. If stratigraphic data are necessary to identify taxa, as is expressed by the authors, then the identification is circular if morphology is not taken into account (Álvaro & Esteve, 2020). For example, the presumed stratigraphic separation between the troodontids Laetinavenatrix mcmasterae and Stenonychosaurus inequalis was the basis of referring specimens to one or the other taxon (van der Reest & Currie, 2017), until it was found that they are not stratigraphically (or morphologically) separate and represent the same taxon, S. inequalis (Cullen et al, 2021).…”

“…In some cases they were unable to narrow down identifications owing to "uncertain stratigraphic position" or, conversely, they ambiguously narrowed down identifications to two taxa based on "high stratigraphic placement" (Paul et al, 2022). However, the taxonomic identification of a specimen must be independent of stratigraphic position or the identification becomes circular (Álvaro & Esteve, 2020). Instead, unique and derived anatomical features should be used to identify specimens.…”

Biostratigraphy of the Ribota and Huérmeda formations (Cambrian Series 2) in the Comarca del Aranda (Zaragoza province), Iberian Chains (NE Spain)

“…In this region, the Iberian Chains show one of the most complete Cambrian record ranging from the Terreneuvian to the Furongian (Liñán et al, 2002(Liñán et al, , 2004Gozalo et al, 2008). Still, the works about the Marianian deposits (comprising the Ribota and Huérmeda formations) are preliminary, mainly focusing on stratigraphy and petrology (Schmidt-Thomé, 1973;Gámez et al, 1991;Zamora et al, 1992Zamora et al, , 1993Álvaro et al, 1995;Palacios & Moczydłowska, 1998;Álvaro et al, 2019), and the trilobite biostratigraphy of those formations is yet to be published. Álvaro et al (2019) studied the trilobite fauna of the first meters of the Huérmeda Formation in various sections of the Mesones tectonostratigraphic unit of the Iberian Chains.…”

“…Luciaspis matiasiÁlvaro, Esteve, Gracia & Zamora, 2019 and Paulaspis tiergaensis Álvaro, Esteve, Gracia & Zamora, 2019 from the lowest levels of the Huérmeda Formation. They also place this subfamily under the family SaukiandidaeHupé, 1953 based on the presence of macropleurae and micropleurae and the subsequent subdivision of the thorax into prothorax and opisthothorax.…”

“…Luciaspis matiasiÁlvaro, Esteve, Gracia & Zamora, 2019 from the base of the Huérmeda Formation of the Iberian Chains, Spain; by original designation. Cambrian Series 2; Spain.…”