First fossil record of early Sarmatian didemnid ascidian spicules (Tunicata) from Moldova |
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| Affiliation: | 1. Shaanxi Key Laboratory of Early Life and Environment, State Key Laboratory of Continental Dynamics, and Department of Geology, Northwest University, Xian 710069, China;2. Department of Geology, GeoBiosphere Science Centre, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden;3. School of Earth Sciences, 125 South Oval Mall, The Ohio State University, Columbus, OH 43210, USA;4. School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul 151-747, Republic of Korea;5. Institut für Geographie und Geologie, Lehrstuhl für Geodynamik und Geomaterialwissenschaft, Am Hubland, 97084 Würzburg, Germany;6. Departamento de Botánica y Geología, Universitat de València, C/ Dr. Moliner 50, E-46100 Burjassot, Spain;7. Institute for Cambrian Studies, 929 25 Road, Grand Junction, CO 81505, USA;8. Nanjing Institute of Geology and Palaeontology, State Key Laboratory of Palaeontology and Stratigraphy, Chinese Academy of Sciences, Nanjing 210008, China;9. Borissiak Paleontological Institute of the Russian Academy of Sciences, Profsoyuznaya 123, Moscow 117997, Russia;10. Siberian Research Institute of Geology, Geophysics and Mineral Resources, Krasny Prospect 67, Novosibirsk 630091, Russia;11. Institut für Geologische Wissenschaften, FU Berlin, Malteserstraße 74-100, Haus D, 12249 Berlin, Germany;12. Institut für Geologie und Mineralogie, Lehrstuhl für Paläontologie und Historische Geologie, Zülpicher Straße 49a, 50674 Köln, Germany |
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| Abstract: | Numerous ascidian spicules are reported for the first time from the lower Sarmatian Darabani-Mitoc Clays of Costeşti, north-western Moldova. The biological interpretation of the studied sclerites allows distinguishing at least three morphospecies (Polysyncraton-like, Trididemnum-like, and Didemnum-like) within the Didemnidae family. Eight other morphological types of spicules are classified as indeterminate didemnids. Most of the studied spicules are morphologically similar to those of Recent shallow-water taxa from the Mediterranean Sea. In contrast, some sclerites resemble those of taxa from the Indo-Pacific region. The greater size of the studied spicules, compared to that of present-day didemnids, suggests favorable physicochemical conditions within the Sarmatian Sea. The presence of these stenohaline tunicates that prefer normal salinity seems to confirm latest hypotheses regarding mixo-mesohaline conditions during the early Sarmatian. |
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| Keywords: | Didemnidae Ascidiacea Sea squirts Middle Miocene Mediterranean gateway Indo-Pacific gateway |
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