Plasticity in the morphology of the fused frontals of Albanerpetontidae (Lissamphibia; Allocaudata)

Guillaume, Alexandre R. D. ; Natario, Carlos ; Mateus, Octavio ; Moreno-Azanza, Miguel (Universidad de Zaragoza)

Resumen: Albanerpetontidae form an enigmatic extinct group of lissamphibians, ranging from the early Bathonian to the early Pleistocene. The Upper Jurassic outcrops of Portugal yield a large collection of material, suitable for addressing the intraspecific variation in and diagnostic potential of the characteristic fused frontals. We revise 58 specimens from the Guimarota beds of the Kimmeridgian Alcobaca Formation and describe 62 new frontal bones from the Kimmeridgian - Tithonian Lourinha Formation. Smaller specimens exhibit a vermicular dorsal ornamentation, while it is polygonal in larger specimens and other albanerpetontids. Compared to small specimens, larger specimens display: (1) larger ventrolateral crests extending posteriorly after the parietal margin; (2) a relatively shorter internasal process; (3) a frontal width across posterior edges relatively smaller; and (4) a ventromedian crest less pronounced. Morphometric analyses suggest a single species with different ontogenetic stages. Specimens are attributed to aff. Celtedens sp., based on a bell-shaped outline with a curved orbital margin (although variable in Portuguese specimens), and a flabellate, bulbous-shaped internasal process. The species is more similar to C. megacephalus than C. ibericus, but its phylogenetic position comprises an unresolved trichotomy. Our results show that intraspecific variation and homoplasy render the fused frontal non-diagnostic below the generic level.

Idioma: Inglés

DOI: 10.1080/08912963.2022.2054712

Año: 2022

Publicado en: Historical Biology 35, 4 (2022), 537-554
ISSN: 0891-2963

Factor impacto JCR: 1.4 (2022)

Categ. JCR: PALEONTOLOGY rank: 30 / 54 = 0.556 (2022) - Q3 - T2

Factor impacto CITESCORE: 3.5 - Agricultural and Biological Sciences (Q2)

Factor impacto SCIMAGO: 0.551 - Agricultural and Biological Sciences (miscellaneous) (Q1)

Tipo y forma: Artículo (PostPrint)

Área (Departamento): Área Paleontología (Dpto. Ciencias de la Tierra)