Milan Chroust

Modern trionychids (Testudines, Cryptodira) have a pan‐tropical distribution, but their range encompassed Central Europe during the Miocene. However, their true Neogene northernmost limit is uncertain because of limited Miocene exposures in the northern half of Europe, including Poland. Here, we address this problem, describing the first Polish remains from this family, coming from three new Middle Miocene vertebrate localities. The material includes isolated shell fragments and an incomplete skull, studied using computed tomography. Through a detailed review of the variation of cranial characters in extant and extinct trionychids, as well as considering the already existing occurrences of the family in the Miocene of Europe, we propose a tentative assignment for this last specimen to Trionyx cf. vindobonensis . This is somehow unexpected since the geographically closest diagnostic records of the family from the Early Miocene of Czechia belong to Rafetus . These new occurrences hint toward an environment still suitable for thermophilic organisms between the Mid‐Miocene Climatic Optimum and Late Miocene “washhouse” climate in the northern part of Central Europe.

The geographic distribution of Crocodylia in Europe throughout the Cenozoic experienced fluctuations in the extension of its northern limit. Whereas crocodylians reached very high latitudes during the early Eocene (78ºN), their northward extension was more moderate during almost the entire Paleogene and the Neogene. Here we reassess previous Early-to- Middle Miocene crocodylian records from the Fore-Carpathian Basin and its foreland, namely from marine limestones of Pińczów (Poland), and Židlochovice (Czechia) and from the new vertebrate site of Szczerców (Poland), currently interpreted as a freshwater paleoenvironment. All crocodylian material from these three sites represents Crocodylia indet. and its possible taxonomic attribution is discussed. The new Szczerców specimen, an osteoderm, represents the world’s northernmost record of a crocodylian from the entire Neogene.

The early Miocene deposits of Bohemia (Czech Republic) contain numerous fragmentary crocodylian remains. Despite this abundance, a detailed taxonomical assignment of these remains was impossible due to the absence of diagnostic cranial elements. Here, we report two partially preserved skulls together with some osteoderms and a partially preserved vertebra from the Tušimice site (MN3, Most Basin, Northwest Bohemia). Though the specimens were from Bohemia, the exact placement of this site was lost during the last century. Our results confirm that the coal from the reported specimens is consistent with the Tušimice site. Based on the detailed cranial description of the new material, the crocodylian remains from the above-mentioned locality can be referred to the extinct alligatoroid Diplocynodon ratelii with confidence. Our data extend the known spatial distribution of this taxon to Central Europe. Les gisements du Miocène inférieur de la région de Bohême (République tchèque) contiennent plusieurs restes fragmentaires de crocodiles. Malgré cette abondance, une assignation taxonomique détaillée de ces restes était impossible à réaliser, du fait de l’absence d’éléments diagnostiques crâniens. Nous rapportons ici deux crânes partiellement préservés ainsi que des ostéodermes et une vertèbre incomplète du site de Tušimice (MN3, bassin du Most, Bohême du Nord-Ouest). Bien que les spécimens soient originaires de Bohême, l’emplacement exact de ce site a été perdu au cours du siècle dernier. Nos résultats ont confirmé que le charbon des spécimens signalés est compatible avec le site de Tušimice. Sur la base de la description crânienne détaillée du nouveau matériel, les restes de crocodiles du site de Tušimice peuvent être rapportés avec certitude à l’alligatoroïde éteint Diplocynodon ratelii. De plus, nos données étendent la distribution spatiale connue de ce taxon, révélant sa présence en Europe centrale.