A new conodont species Tortodus dodoensis sp. nov. from the lower part of the Givetian (Middle Devonian) of the Mackenzie Mountains (NW Canada) is described. This paper also reports the lowest stratigraphic occurrence of a Givetian fauna containing a.o. Polygnathus amphora, P. denisbriceae, P. xylus ensensis, P. pseudoeiflius, P. linguiformis klapperi s.l., P. l. weddigei, P. parawebbi and P. pseudofoliatus from the northern Mackenzie Mountains. This fauna situates the sample in the timorensis to ansatus zones interval, possibly restricting it to the timorensis Zone. This result allows the positioning of the Eifelian–Givetian contact within the lowest 7.5 m of the Hare Indian Formation (Horn River Group) (northern Mackenzie Mountains, NW Territories).

中文翻译：

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来自加拿大西北麦肯奇山北部的新牙形亚目Tortodus dodoensis和一种吉文天体（中泥盆纪）牙形动物群

牙形石新物种Tortodus dodoensis sp。十一月 从麦肯齐山脉（加拿大西北部）的吉维田（中泥盆纪）下部描述。本文还报道了吉旺动物区系的最低地层学特征，该动物区系包括a。Polygnathus amphora，P。denisbriceae，P。xylus ensensis，P。pseudoeiflius，P。linguiformis klapperi sl 。，P. l。北部麦肯齐山脉的野菜，副对虾和假叶对虾。此动物座落在样品timorensis到ansatus区间隔，可能将其限制到timorensis区。这一结果可以使伊比利亚-吉夫提斯人接触点定位在野兔印度组（霍恩河群）（西北地区麦肯齐山北部）的最低7.5 m范围内。