TY - JOUR N2 - Six enigmatic fossils from the Famennian (Devonian) Cleveland Shale in Ohio, U.S.A., are interpreted here as arthrodiran (Placodermi) egg cases. Recognition as egg cases is confirmed based on the observation of layered collagen fibers. The presence of a tuberculated bone fragment preserved within one case confirms a vertebrate source. The nature of the tubercles and the unique morphology of the egg cases supports the interpretation of an arthrodiran source. Reports of Devonian egg cases are limited to either assumed chondrichthyan producers or a putative ‘egg sac’ with a morphology atypical for any vertebrate. The Cleveland Shale egg cases thus represent the first record for a non-chondrichthyan producer. Among placoderms, behaviors of a pelagic life style with obligate nesting sites, reef fishes with live birth, and estuarine and fluvial nurseries, along with eggcase oviparity testifies to the diversity of reproductive strategies. As with modern fishes these strategies may be ecologically driven and the derived and variable reproductive biology of extant chondrichthyans is actually a primitive condition among gnathostomes. One consequence of the diversity of reproductive strategies (dependent on the topology of relationships) is the independent origin of internal fertilization within placoderms, possibly suggesting external fertilization as the primitive gnathostome reproductive mode. L1 - http://journals.pan.pl/Content/108909/PDF-MASTER/07_Carr_Jackson.pdf L2 - http://journals.pan.pl/Content/108909 PY - 2018 IS - No 3 EP - 389 KW - Devonian KW - Famennian KW - Cleveland Shale KW - Ohio KW - U.S.A. KW - Placodermi KW - Arthrodira KW - Oviparity KW - Egg Case A1 - Carr, Robert K. A1 - Jackson, Gary PB - Komitet Nauk Geologicznych PAN PB - Wydział Geologii UW VL - vol. 68 DA - 2018.10.01 T1 - A preliminary note of egg-case oviparity in a Devonian placoderm fish SP - 381 UR - http://journals.pan.pl/dlibra/publication/edition/108909 T2 - Acta Geologica Polonica ER -