Research Paper
Dermal skeleton of the stem osteichthyan Ligulalepis from the Lower Devonian of New South Wales (Australia)
CAROLE J. BURROW
Geosciences Programme, Queensland Museum, 122 Gerler Rd, Hendra Qld 4011, Australia, carole.burrow@gmail.com
Corresponding author
GAVIN C. YOUNG
Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University ACT 2601, Australia, gavinyoung51@gmail.com
JING LU
Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China,, lujing@ivpp.ac.cn
ABSTRACT
When first described based on isolated scales, Ligulalepis was assigned to the Palaeoniscoidea, a basal group of actinopterygians (ray-finned fishes). Recent cladistic analyses, mainly based on skull and neurocranial characters, have mostly recovered the taxon (or, ‘Ligulalepis’) as a stem osteichthyan. Here we present information on Ligulalepis dermal 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 compare closely with those of basal actinopterygians, whereas the spine-like element shows some similarity to the distal end of the spines on medial dorsal plates of the Chinese Late Silurian stem osteichthyans Guiyu and Sparalepis,or alternatively to fin rays on the stem osteichthyan Dialipina. One of the jaw elements appears to be a compound jugal plate plus part of the dentate maxilla, an arrangement not previously known in any Devonian stem osteichthyan, or actinopterygian. Histological structure of dermal plates somewhat resembles that of Meemannia, but pore openings in Ligulalepis lead only to the vascular canal network at the base of the ornament layer and not to a pore canal network. Like previous phylogenetic analyses, our analysis incorporating post-cranial dermal skeleton characters also recovered Ligulalepis as a stem osteichthyan.
Key words: Emsian, Osteichthyes, Gleninga Formation, Troffs Formation, Taemas Formation, palaeohistology.
How to cite: Burrow, C. J., Young. G. C., & Lu. J. 2023. Dermal skeleton of the stem osteichthyan Ligulalepis from the Lower Devonian of New South Wales (Australia). Spanish Journal of Palaeontology, 38(1), 23-36.
Received 30 November 2022, Accepted 1 May 2023, Published online 12 May 2023
https://doi.org/10.7203/sjp.26575
