Late Devonian aquatic environments hosted the fin-to-limb transition in vertebrates. Upper Devonian (ca. 365–360 Ma) strata in Pennsylvania, USA, preserve a diversity of fishes and tetrapods in coastal marine to fluvial depositional environments, making this region ideal for investigating the ecology and evolution of Late Devonian vertebrates. A key unresolved issue has been reconstructing the specific aquatic habitats that hosted various vertebrates during this period. Specifically, the salinity of environments spanning fresh to shallow marine water is difficult to discern from sedimentological and paleontological analyses alone. Here, we analyze rare earth elements and yttrium (REY) as well as stable oxygen and sulfur isotope compositions (δ18O, δ34S) in fossil vertebrate bioapatite from late Famennian (ca. 362–360 Ma) strata of the Catskill and Lock Haven formations in the Appalachian Basin, USA, to determine the relative salinity of their aquatic environments. These results confirm the ecological euryhalinity of several taxa (Bothriolepis sp., tristichopterids, and Holoptychius sp.). Our results are the first demonstrating that some early tetrapod species occupied unequivocally freshwater habitats by late Famennian time (ca. 362–360 Ma). Our study shows that integrating sedimentological and paleontological data with combined oxygen and sulfur isotope analysis allows precise tracing of the relative salinity of vertebrate habitats deep in the past.
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RBINS Staff Publications 2024
The domestic cat (Felis catus) descends from the African wildcat Felis lybica lybica. Its global distribution alongside humans testifies to its successful adaptation to anthropogenic environments. Uncertainty remains regarding whether domestic cats originated in the Levant, Egypt, or elsewhere in the natural range of African wildcats. The timing and circumstances of their dispersal into Europe are also unknown. In this study, the analysis of 87 ancient and modern cat genomes suggests that domestic cats did not spread to Europe with Neolithic farmers. Conversely, they were introduced to Europe around 2000 years ago, probably from North Africa. In addition, a separate earlier introduction (first millennium before the common era) of wildcats from Northwest Africa may have been responsible for the present-day wild population in Sardinia. Tracing the origins of domestic cats (Felis catus) has been limited by a lack of ancient DNA for these animals, as well by their morphological similarity to the African wildcat (F. lybica lybica) and European wildcat (F. sylvestris). De Martino et al. generated low- to medium-coverage genomes for 87 ancient, museum, and modern cats (see the Perspective by Losos). They found that domestic cats are most genetically similar to African wildcats, although there has been widespread gene flow between wild and domestic populations. European samples that cluster with domestic cats only appear in the 1st century CE, suggesting a later dispersal of domestic cats than previously thought. Although broader sampling is needed, this study shows the complexity of population dynamics that is often revealed when looking beyond mitochondrial DNA.
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RBINS Staff Publications 2025
