RT Journal Article T1 First isotopic and multidisciplinary evidence for nonmarine coelacanths and pycnodontiform fishes: palaeoenvironmental implications A1 Poyato-Ariza, F. J. A1 Talbot, M. R. A1 Fregenal Martínez, María Antonia A1 Meléndez Hevia, María Nieves A1 Wenz, S. AB The Recent coelacanth Latimeria chalumnae, one of the best known `living fossils', dwells in deep marine water. Fossil coelacanths have been globally related to marine environments, specially after the Triassic, an association that has led to a general belief that they have always been marine. Previous reports of fossil coelacanths in continental deposits have been largely neglected. Prior to this report, uncontested Cretaceous freshwater coelacanths were unknown. In turn, the pycnodontiform fishes have always been considered exclusively marine, apart from a few controversial exceptions. Here we present the first multidisciplinary evidence for nonmarine coelacanths and pycnodonts. Our conclusions are based upon palaeogeographic, sedimentologic, taphonomic, and palaeoecologic criteria, strongly supported by strontium (87Sr–86Sr) and stable carbon and oxygen isotopic studies. The coelacanth, provisionally attributed to the genus `Holophagus', and the pycnodontiforms Eomesodon sp. and Macromesodon aff. bernissartensis were unearthed at the Early Cretaceous locality of Las Hoyas (Cuenca, Spain), where they grew in and inhabited a freshwater environment without marine influence. Fossil coelacanths and pycnodonts cannot, therefore, be used as unambiguous indicators of a marine environment. Caution is needed when using a single or a few taxa as palaeoenvironmental indicators, especially fish; in this sense, communities are much more reliable. Arguments based on actualism or taxonomic uniformitarianism, morphologic convergence and functional morphology are truly significant only within the framework of a sound multidisciplinary approach to the study of the palaeoenvironment. PB Elsevier SN 0031-0182 YR 1998 FD 1998-11-15 LK https://hdl.handle.net/20.500.14352/118514 UL https://hdl.handle.net/20.500.14352/118514 LA eng NO Poyato-Ariza, F. J., Talbot, M. R., Fregenal-Martı́nez, M. A., Meléndez, N., & Wenz, S. (1998). First isotopic and multidisciplinary evidence for nonmarine coelacanths and pycnodontiform fishes: Palaeoenvironmental implications. Palaeogeography, Palaeoclimatology, Palaeoecology, 144(1-2), 65-84. https://doi.org/10.1016/S0031-0182(98)00085-6 NO Junta de Comunidades de Castilla–La Mancha NO Dirección General de Investigación Científica y Técnica (España) NO Human Capital and Mobilities (Unión Europea) DS Docta Complutense RD 10 abr 2025