Sulcusuchus (Polycotylidae) gastroliths + trace fossils of floating reptiles from Triassic of Spain + mosasaurs

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

Marine reptile papers:

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José P. O’Gorman, Franco R. Aspromonte & Gonzalo Matelo Mirco (2025)
First record of lithophagy in Sulcusuchus erraini (Plesiosauria; Polycotylidae) with comments on the taphonomic and collect bias in gastroliths
Historical Biology (advance online publication)
doi: https://doi.org/10.1080/08912963.2025.2548329
https://www.tandfonline.com/doi/full/10.1080/08912963.2025.2548329


Gastroliths have long been reported in marine reptiles and are particularly well documented in elasmosaurid plesiosaurs, while their occurrence in short-necked polycotylids is notably rare. Here, we report the first documented occurrence of lithophagy in the polycotylid plesiosaur Sulcusuchus erraini Gasparini & Spalletti, based on 95 gastroliths recovered from the Maastrichtian levels of La Colonia Formation, Chubut, Patagonia Argentina. The MPEF-PV 11698 (MPEF, Museo Paleontológico Egidio Feruglio) represents one of the few records of lithophagy in polycotylids and is the first for the Maastrichtian stage. The observed shapes are mainly classified as discoidal or spherical. Morphometric analysis using the Maximum Projection Sphericity index (Ψ; mean = 0.7, standard deviation = 0.1) and the Oblate – Prolate index (OP; mean = 0.08, standard deviation = 4.71) suggests a probable fluvial origin. To assess the potential taphonomic bias on Ψ and OP values, two analyses were performed: one using correlation and a second one considering resampling analysis. The results of both indicated that the mean index values remain robust even with up to 50% loss of the gastrolith cluster. The maximum transverse section observed (12.24 cm2) within the gastrolith cluster suggests that S. erraini possessed a relatively large oesophagus compared to other plesiosaurs analyzed.

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Free pdf:

Javier Cardenal & Matias Reolid (2025)
Trace fossils of floating reptiles from the Carnian in the Tabular Cover (S Spain)
Estudios Geológicos 81(1): 1125
doi: https://doi.org/10.3989/egeol.45687.1125
https://estudiosgeol.revistas.csic.es/index.php/estudiosgeol/article/view/1125

Free pdf:
https://estudiosgeol.revistas.csic.es/index.php/estudiosgeol/article/view/1125/1451



Small trace fossils are recorded in the top and the bottom of a thin sandstone bed located in the upper part of the K1 unit (lower Carnian, Upper Triassic), in the Tabular Cover. In the top surface, two trace fossils have been identified: a tridactyl digitigrade elongated scratch mark with preserved triangular claws (20 mm long and 19 mm wide), with two lateral elongated (30 mm) and curved marks are located back to the margins of the tridactyl foot-print, and a longitudinal furrow (185 mm long and 3 mm wide). In the bottom surface there are two autopodium impressions preserved as convex hyporeliefs, counter moulds (45 mm long, 26 mm wide, and 18 mm long, 14 mm wide). They are tridactyl, elongated scratch marks, located very close and forming an angle of 48º. Trace fossils are interpreted as produced on the bottom by small tetrapods when floating in a low energy shallow environment. In the top surface correspond to the right hindlimb and the tail. In the bottom surface the scratch marks are more elongated and may be related to pes and manus. The potential authors are uncertain. This is a new example of swimming trace fossil for the Carnian deposits of the southern and eastern Iberia.

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Also:

This is a preprint for now, but might be of interest:

Trevor H. Rempert, Eli Strell, Joel Crothers, Lucas C. Hartley, and Hugo Yip (2025)
Select Specimens from the Mosasaur Collections at the University of Colorado Boulder
Preprint
DOI: 10.31233/osf.io/5chdt_v1
https://www.researchgate.net/publication/394435456_Select_Specimens_from_the_Mosasaur_Collections_at_the_University_of_Colorado_Boulder 

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Not yet mentioned:

Correspondence:

Trevor H. Rempert & Brennan P. Martens (2025)
On the supposed presence of Prognathodon solvayi in the Demopolis Chalk
Mesozoic 2(2): 139–141
DOI: 10.11646/mesozoic.2.2.2
https://mapress.com/mz/article/view/mesozoic.2.2.2


While reporting on the mosasaurid fauna of the upper Demopolis Chalk of western Alabama and northeastern Mississippi, Derstler (1988) noted the presence of numerous remains of Plioplatecarpus sp. and Mosasaurus conodon, and a single isolated tooth of Prognathodon cf. Prognathodon solvayi. These remains are of Late Campanian age, originating from within a few meters of the lower boundary of the Bluffport Marl Member.