Skeletal taphonomy of the water frogs (Amphibia: Anura) from the Pit 7/8 of the Pliocene Camp dels Ninots site (Caldes de Malavella, NE Spain)

ABSTRACT

The Pliocene lacustrine infill of Camp dels Ninots maar (Girona, Spain) hosts an exceptional record of complete articulated skeletons. Here we present the taphonomical description of 22 fossil water frogs recovered from the Pit 7/8 of Can Argilera Sector. Description of their skeletal taphonomy is done on the basis of their distribution, completeness, articulation and limb position, and by establishing comparisons with the late Miocene site of Libros (Spain). Microscopic examination shows no evidence of digestion and absence of weathering. Mass mortality or any environmental stress-induced factors cannot be ruled out, but natural death seems to be the most probable. Limited time of decay prior burial seems to be the main pattern explaining the relatively high degree of articulation and completeness. Floatation is not to be disregard for some more (proximally) disarticulated specimens. Taphonomical patterns document two types of sub-environments inside a cool and deep lake, suggesting a more complex depositional scenario for Camp dels Ninots than the ones described in others similar Konservat-Lagerstätten.

KEYWORDS:

• Pelophylax
• Pliocene
• Lagerstätte
• taphonomy
• cause of death

Acknowledgments

Authors would like to thank the excavation teams that worked at Camp del Ninots since 2006, as well as the former restauration team Dr. Lucia López-Popín Dolhaberriague and Dr. Souhila Roubach. HAB would like to thanks the personal from the different institutions hosting the water frog specimens from the late Miocene of Libros checked for this study: Susana Fraile Gracia, Curator of the Colección de Paleontología de Vertebrados y de Prehistoria, Museo Nacional de Ciencias Naturales, CSIC (Madrid, Spain); Hermano Miguel Pérez Sanz, Curator of the Museo del Colegio La Salle (Teruel, Spain); Vicent Vicedo, Director of the Museo de Geología de Barcelona (Spain); Sebastián C. Calzada, Director of the Museo Geológico del Seminario de Barcelona (Spain); Josep Robles, Collection manager at the Institut Català de Paleontologia Miquel Crusafont, Universitat Autònoma de Barcelona; Rainer Brocke, Curator of the fossil vertebrate collection, Senckenberg Forschungsinstitut und Naturmuseum Frankfurt (Germany), as well as Gunnar Riedel and Sven Tränkner from the same institution; and Mike Day, Curator of non-mammalian tetrapods, Department of Earth Sciences, Natural History Museum (London, United Kingdom). Two anonymous reviewers are acknowledged for their comments on an earlier version of this manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplemental data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/08912963.2023.2237998

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This study is part of the projects [CGL2011-13293-E/BTE] “Estudio paleontologico y preparación de los microvertebrados del Plioceno de Camp dels Ninots, Girona” (Spanish Ministry of Science and Innovation), [SGR2021-01238] (Generalitat de Catalunya), SYNTHESYS [grant DE-TAF-3244 to HAB] (EC funded project), projects [CLT009/18/00052] and [CLT009/22/00043] “El Plio-pleistocè del Camp dels Ninots i la depressió prelitoral: evolució paleoclimàtica, dispersions faunístiques i humanes II and III” (Cultural Department of the Government of Catalonia).This research was funded by project [GAČR 21-33751S] of the Czech Science Foundation, and projects [2017 SGR-859] and [SGR2021-01238] from the Government of Catalonia (AGAUR). The research of HAB, IC, AMM, ALM, EMR, FG, JA, GC, and BGS is funded by the CERCA Programme/Generalitat de Catalunya. HAB is funded by project [PID2021-122533NB-I00] and JA, GC, and BGS are funded by project [PID2021- 123092NB-C21] from the Spanish Ministry of Science and Innovation [MCIN/AEI/10.13039/501100011033/FEDER, UE]. TP is supported by the Institute of Geology of the Czech Academy of Sciences [RVO67985831]. AMM and FG are supported by the Agència de Gestió d’Ajuts Universitaris i de Recerca (AGAUR) and the Departament d’Empresa I Coneixement de la Generalitat de Catalunya grants 2021FI_B200207 and 2022FI_B00383 respectively. The research technical support of EMR was supported by the Spanish Ministry of Science and Innovation through the “Maria de Maeztu” excellence accreditation [CEX2019-000945-M]. The Institut Català de Paleoecologia Humana i Evolució Social (IPHES-CERCA) has received financial support from the Spanish Ministry of Science and Innovation through the ‘María de Maeztu’ program for Units of Excellence [CEX2019-000945-M].