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首页> 外文期刊>Acta Palaeontologica Polonica >Early Pennsylvanian xenacanth chondrichthyans from the Swisshelm Mountains, Arizona, USA
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Early Pennsylvanian xenacanth chondrichthyans from the Swisshelm Mountains, Arizona, USA

机译：来自美国亚利桑那州Swisshelm山的宾夕法尼亚州早期xenacanth软骨鱼类

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摘要

Three genera of xenacanths, based oil isolated teeth, occur in the lepospondyl (amphibian)-dominated fauna from the upper Black Prince Limestone (late Bashkirian). Orthacanthus donnelljohnsi sp. nov. teeth, with carinae lacking serrations oil the compressed principal cusps, and only one intermediate cusp, represent both adult and juvenile teeth. Heterodonty occurs in both adult and juvenile dentitions. The absence of serrations is unique among Pennsylvanian species of Orthacanthus. Teeth with often highly asymmetrical bases with an aborally-flexed lingual marginal flange (= anterolingual shelf) and a single intermediate cusp are assigned to Triodus elpia sp. nov. A central foramen occurs in the base, unlike most other species; the moderately compressed principal cusps bear generally straight cristae. They represent the first reported Occurrence of Triodus in the Paleozoic of North America. Five teeth, with cristae extending from the cusps onto their bases, belong to Bransonella. Two are questionably assigned to Bransonella nebraskensis, one to B. ?lingulata with its labio-lingually elongated apical button and smaller than normal intermediate Cusp, and one each to Bransonella sp. "A" and "B". Bransonella sp. "A" has a base wider (labio-lingual) than long, the reverse of the other Bransonella teeth. Bransonella sp. "B" is distinctly different, as it lacks an intermediate Cusp (as in some B. lingulata teeth), and the basal tubercle is beneath one of the cusps (with no evidence of deformity).
机译：Xenacanths的三个属，是油基分离的牙齿，出现在黑王子石灰石（晚期Bashkirian）的以脂多糖（两栖动物）为主的动物群中。 Orthacanthus donnelljohnsi sp。十一月缺乏锯齿的隆突的牙齿为受压的主要牙尖加油，只有一个中间牙尖既代表成年牙齿，也代表少年牙齿。在成人和青少年牙列中都会发生异齿症。在宾夕法尼亚州的Orthacanthus物种中，没有锯齿的现象是独特的。 Triodus elpia sp。的牙齿通常具有高度不对称的基部，并具有弯曲的舌侧边缘凸缘（=舌前架子）和单个中间尖点。十一月与大多数其他物种不同，基部有一个中央孔。适度压缩的主尖瓣通常呈笔直状。它们代表了在北美古生代首次报道的Triodus发生。布兰森氏菌属于五个齿，cr齿从齿尖延伸到基部。有两个可疑地被分配给内布拉斯加州种（Bransonella nebraskensis），一个被分配给B. flingulata，其唇舌长舌尖，并且比正常的中间Cusp小，而每个则被分配给Bransonella sp。 “ A”和“ B”。布兰氏菌“ A”的基部（唇舌）长于其他Bransonella牙齿的齿长。布兰氏菌“ B”明显不同，因为它没有中间尖锐的尖刺（如在某些舌齿双歧杆菌齿中），并且基底结节在尖齿之一下方（没有畸形的证据）。

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