The Eocene La Meseta Formation on Seymour Island, Antarctic Peninsula, is known for its remarkable wealth of fossil remains of chondrichthyans and teleosts. Chondrichthyans seemingly were dominant elements in the Antarctic Paleogene fish fauna, but decreased in abundance from middle to late Eocene, during which time remains of bony fishes increase. This decline of chondrichthyans at the end of the Eocene generally is related to sudden cooling of seawater, reduction in shelf area, and increasing shelf depth due to the onset of the Antarctic thermal isolation. The last chondrichthyan records known so far include a chimeroid tooth plate from TELM 6 (Lutetian) and a single pristiophorid rostral spine from TELM 7 (Priabonian). Here, we present new chondrichthyan records of Squalus, Squatina, Pristiophorus, Striatolamia, Palaeohypotodus, Carcharocles, and Ischyodus from the upper parts of TELM 7 (Priabonian), including the first record of Carcharocles sokolovi from Antarctica. This assemblage suggests that chondrichthyans persisted much longer in Antarctic waters despite rather cool sea surface temperatures of approximately 5°C. The final disappearance of chondrichthyans at the Eocene–Oligocene boundary concurs with abrupt ice sheet formation in Antarctica. Diversity patterns of chondrichthyans throughout the La Meseta Formation appear to be related to climatic conditions rather than plate tectonics.

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Citation for this article: Kriwet, J., A. Engelbrecht, T. Mörs, M. Reguero, and C. Pfaff. 2016. Ultimate Eocene (Priabonian) chondrichthyans (Holocephali, Elasmobranchii) of Antarctica. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1160911.

南极半岛西摩岛上的始新世拉梅塞塔组以其丰富的软骨鱼类和硬骨鱼化石遗迹而闻名。软骨鱼类似乎是南极古近纪鱼类动物群中的主要元素，但在始新世中晚期，软骨鱼类的数量减少，在此期间硬骨鱼类的残留量增加。始新世末期软骨鱼类的这种减少通常与海水突然冷却、大陆架面积减少以及由于南极热隔离的开始而增加的大陆架深度有关。迄今为止已知的最后一个软骨鱼类记录包括来自 TELM 6（Lutetian）的嵌合体牙板和来自 TELM 7（Priabonian）的单个 prisiophorid 喙棘。在这里，我们提出了新的软骨鱼类记录来自 TELM 7 (Priabonian) 上部的Squalus、Squatina、Prisiophorus、Striatolamia、Palaeohypotodus、Carcharocles和Ischyodus ，包括来自南极洲的Carcharocles sokolovi的首次记录。这种组合表明，尽管海面温度相当凉爽，约为 5°C，但软骨鱼类在南极水域的生存时间要长得多。始新世-渐新世边界处软骨鱼类的最终消失与南极洲冰盖的突然形成同时发生。整个 La Meseta 组的软骨鱼类的多样性模式似乎与气候条件有关，而不是与板块构造有关。

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本文引用：Kriwet, J.、A. Engelbrecht、T. Mörs、M. Reguero 和 C. Pfaff。2016.南极洲的终极始新世（普里亚波尼亚）软骨鱼（Holocephali，Elasmobranchii）。脊椎动物古生物学杂志。DOI：10.1080/02724634.2016.1160911。