The systematics and phylogeny of the Devonian subfamily Asteropyginae (Trilobita: Phacopida)

Abstract

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A revision of the first Asteropyginae (Trilobita; Devonian)

“…from Bignon and Crônier, 2014): Cephalon may have a prefrontal spine; frontal lobe diamond shaped; axial furrows straight between S1 and S3, no contact between S2 and axial furrows; 5-8 lenses per vertical row on visual surface; genal spine shorter than glabella with narrow proximal portion; narrow anterior border, lateral border very large, poorly or developed on genal spine. Pygidium with anterior pleural bands as wide and elevated as posterior bands, flat pleural bands; axis with 7-10 rings; 4 or 5 pleural segments; 4 or 5 pairs of pygidial spines shorter than pleural width (tr.…”

“…Order PHACOPIDA Salter, 1864Suborder PHACOPINA Struve, 1959 Superfamily ACASTACEA Delo, 1935 Family ACASTIDAE Delo, 1935 Subfamily ASTEROPYGINAE Delo, 1935 Genus Minicryphaeus Bignon andCrônier, 2014 Type species: M. minimus (Morzadec, 2001), from the Pragian (Lower Devonian) of Morocco.…”

“…three species that he attributed to the genus Pseudocryphaeus. After the review by Bignon and Crônier (2014), these species (M. minimus, M. quaterspinosus and M. sarirus) were determined as forming a distinct genus: Minicryphaeus. Indeed, these two genera are closely related, as obvious from the pleural structure (shape and size of the pleural bands, connexion between pleural bands and pygidial spines), S1 straight, L2 and L3 with similar length and a wide cephalic posterior border furrow.…”

“…This work suggests Destombesina as the sister-group of all Asteropyginae members. However, the proposition that this genus is the common ancestor remains somewhat debatable since it depends on the affiliation of this genus within this subfamily or within the Acastavinae (Bignon and Crônier, 2014). Consequently, Minicryphaeus was the most ancestral Asteropyginae that they can identify with certainty (Bignon and Crônier, 2014).…”

“…(R. and E. Richter, 1954), are included in a data matrix used to solve the phylogeny of the subfamily (Bignon and Crônier, 2014). Such new developments bring pertinent information about the origin of this trilobite subfamily and an explanation of the difference between former phylogenies proposed and the new one (Bignon and Crônier, 2014).…”