Bardack D, Zangerl R
Science. 1968 Dec 13;162(3859):1265-7. doi: 10.1126/science.162.3859.1265.
A fossil record of lampreys has previously been unknown. A new genus demonstrates the presence of this group in the Pennsylvanian. The body outline, parts of the head skeleton, rasping tongue mechanism, gill basket, and other internal organs are preserved. The fossils are very similar in structure to modern forms. The absence of hagfish characters in the fossil supports the view that the common ancestor of lampreys and hagfishes lived prior to the Pennsylvanian.
此前，七鳃鳗的化石记录尚不为人所知。一个新属表明了该类群在宾夕法尼亚纪的存在。其身体轮廓、部分头部骨骼、锉舌机制、鳃篮及其他内部器官得以保存。这些化石在结构上与现代形态非常相似。化石中没有盲鳗的特征，这支持了七鳃鳗和盲鳗的共同祖先生活在宾夕法尼亚纪之前的观点。
