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in Ruciński, Campos, Mateus et Werneburg, 2025. |
ABSTRACT
Recent fieldwork in the Upper Triassic deposits of the Silves Group in the Algarve, southern Portugal revealed novel cyamodontid placodont material. The collection includes a partial skull and numerous isolated armor plates from four localities in Silves and Loulé municipalities. The skull shows a strong affinity to henodontid placodonts, especially to Henodus chelyops from Tübingen-Lustnau in Germany. It shares features such as a rectangular outline of the cranium, occurrence of a broad spatulate rostrum, and toothless maxillae with curved longitudinally extending grooves. The only unambiguous difference observed pertains to the more robust and convex snout shape of the new specimen. Based on these multiple similarities, the specimen is identified as Henodus sp., but poor preservation prevents species-level identification. The new specimen from Portugal represents the second record of Henodus and illustrates a wider geographic distribution of that genus, extending beyond the Germanic Basin and reaching coastal areas near the westernmost branch of the Neotethys. The age of the deposits where the cranium was found is not well-established but refers to a time interval within the upper Carnian–Rhaetian, suggesting the specimen may be younger than other henodontid records. The novel Henodus material found in the continental, but likely the near-coastal depositional setting, concurs with the known records of brackish to the freshwater habitat of the other henodontid placodonts. The occurrence of abundant armor plates assigned to Cyamodontidae at multiple sites and stratigraphic horizons indicates that placodonts were common in the south Iberian margin.
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| Paleogeographic context of recorded Henodontidae remains. A, paleogeographic map of the world during the Late Triassic (Colorado Plateau Geosystems Inc., license nr. #110719). B, magnification of the map of the Late Triassic world illustrating the area of the western Neotethys. Approximate locations of Henodontidae-bearing sites are indicated by a star. Drawing of Henodus chelyops after Rieppel et al. (2000). Drawing of Parahenodus atacensis after de Miguel Chaves et al. (2018). Photos of the Portuguese specimen ML. A9182 is referred to as Henodus sp. with shape contour and established bone extensions (compare with Figs 4, 5). Scale bars represent 20 mm. Abbreviations: AB, Algarve Basin; AV, Avalonia; BM, Bohemian Massif; CEB, Central European Basin (which includes Germanic Basin); EEP, East European Platform; IB, Iberian Basin; IM, Iberian Massif; MG, Maghrabian-Gibraltar rift; SP, Sahara Platform. |
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| Summary of the placodont material from Upper Triassic of the Algarve. A, reconstruction of Henodus by Jakub Kowalski and Piotr Janecki. B, transversely expanded armor plate from Algarve, interpreted to possibly stem from the medial portion of Henodus carapace. C, equilateral armor plate from the Algarve interpreted to possibly stem from the marginal portion of Henodus carapace. D, photogrammetry-based image of Henodus cranium (ML. A9182). |
Maciej Ruciński, Hugo Campos, Octávio Mateus and Ingmar Werneburg. 2025. Novel Record of Placodont Remains including A Henodus Cranium from the Upper Triassic Silves Group of the Algarve, southern Portugal. Journal of Vertebrate Paleontology. e2460445. DOI: doi.org/10.1080/02724634.2025.2460445
