ABSTRACT. New fossils of “Gyracanthus” sherwoodi Newberry, 1889 are described primarily from the Late Devonian Red Hill site and Metzger's Quarry (Catskill Formation, late Famennian) of Clinton and Sullivan Counties in central Pennsylvania. The fossils include ornamented prepectoral ventral plates, pectoral, pelvic, and dorsal fin spines, elements of the endoskeletal shoulder girdle (procoracoid and scapulocoracoid), scales, and possible anal fin spines. We distinguish between anterior and posterior dorsal fin spines. A growth series of elements, described for the first time for a gyracanth, show that the adults of this taxon reached about a meter in length, and juveniles already had ossified endoskeletal pectoral elements at body lengths 300–400 mm. The mainly cartilaginous skeleton, paired fin spines, shoulder girdle structure, and scale growth are consistent with gyracanthids being stem chondrichthyans. “Gyracanthus” sherwoodi lived in non-marine conditions in the eastern Laurentian rivers and deltas.

中文翻译：

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来自北美晚泥盆世的“Gyracanthus”sherwoodi（Gnathostomata，Gyracanthidae）

摘要。1889 年的“Gyracanthus”sherwoodi Newberry 的新化石主要来自宾夕法尼亚州中部的克林顿县和沙利文县的晚泥盆世红山遗址和梅茨格采石场（卡茨基尔组，晚法门阶）。化石包括装饰的胸前腹板、胸鳍、骨盆和背鳍棘、内骨骼肩带的元素（前喙突和肩胛骨）、鳞片和可能的臀鳍棘。我们区分前后背鳍棘。首次描述了暴龙类的一系列生长元素，表明该分类群的成虫长度达到了约 1 米，而幼虫的体长 300-400 毫米已经骨化了胸骨内元件。主要是软骨骨骼，成对的鳍棘，肩带结构，和规模增长与 gyracanthids 是茎软骨鱼类一致。“Gyracanthus”sherwoodi 生活在劳伦河东部和三角洲的非海洋环境中。