Dermal skeleton of the stem osteichthyan Ligulalepis from the Lower Devonian of New South Wales (Australia)

• Burrow, Carole J. ^[1] ; Young, Gavin C. ^[2] ; Lu, Jing ^[3]
  1. [1] Universitat de València

     Universitat de València

     Valencia, España

     
  2. [2] Australian National University

     Australian National University

     Australia

     
  3. [3] Chinese Academy of Sciences

     Chinese Academy of Sciences

     China

     

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• Localización: Spanish journal of palaeontology, ISSN 2255-0550, Vol. 38, Nº. 1, 2023 (Ejemplar dedicado a: SPANISH JOURNAL OF PALAEONTOLOGY), págs. 23-35
• Idioma: inglés
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• Resumen

  • When first described based on isolated scales, Ligulalepis was assigned to thePalaeoniscoidea, a basal group of actinopterygians (ray-finned fishes). Recent cladisticanalyses, mainly based on skull and neurocranial characters, have mostly recovered thetaxon (or, ‘Ligulalepis’) as a stem osteichthyan. Here we present information on Ligulalepisdermal elements other than scales and skulls, that include a cheek fragment, a premaxilla,other marginal jaw elements and teeth, an accessory vomer, a partial shoulder girdle,incomplete spine-like elements, and a gular plate. The shoulder girdle and premaxilla compareclosely with those of basal actinopterygians, whereas the spine-like element showssome similarity to the distal end of the spines on medial dorsal plates of the Chinese LateSilurian stem osteichthyans Guiyu and Sparalepis, or alternatively to fin rays on the stemosteichthyan Dialipina. One of the jaw elements appears to be a compound jugal plate pluspart of the dentate maxilla, an arrangement not previously known in any Devonian stemosteichthyan, or actinopterygian. Histological structure of dermal plates somewhat resemblesthat of Meemannia, but pore openings in Ligulalepis lead only to the vascular canalnetwork at the base of the ornament layer and not to a pore canal network. Like previousphylogenetic analyses, our analysis incorporating post-cranial dermal skeleton charactersalso recovered Ligulalepis as a stem osteichthyan.