<i>Tohoraonepu nihokaiwaiu-</i>Supplementary Data.docx

The Kekenodontidae are late-surviving archaeocetes from the Late Oligocene of Southwest Pacific that includes a single-named species, <i>Kekenodon onamata</i>. <i>Tohoraonepu nihokaiwaiu </i>is a new genus and species of small body-sized kekenodontid from the upper Oligocene (Chattian) Kokoamu Greensand of Otago, South Island, New Zealand. Phylogenetic analyses recover <i>T</i>. <i>nihokaiwaiu </i>within a monophyletic Kekenodontidae, forming a clade with an unnamed provisional kekenodontid, OU 22023. Kekenodontids are recovered crownward to basilosaurids and stemward to a paraphyletic group of toothed ‘mysticetes’ that are excluded from Neoceti. The analyses confirm the identification of kekenodontids as the latest-diverging archaeocetes that persisted into the Late Oligocene. The holotype OU 22394 is a juvenile individual preserving several isolated heterodont teeth with characteristics of deciduous teeth, including unmineralized pulp cavities and cheek teeth with lower-lying triangular crowns that are different from all known kekenodontids. Diphyodonty is known from Eocene archaeocetes but is unknown from geologically younger toothed cetaceans, with monophyodonty being hypothesized for all Neoceti. Inferences of diphyodonty in <i>T</i>. <i>nihokaiwaiu </i>would be the first instance in Cetacea from rocks geologically younger than the Eocene and would indicate diphyodonty persisted in some Late Oligocene archaeocetes.

凯肯鲸科（Kekenodontidae）是一类孑遗的古鲸类（Archaeoceti），生存于西南太平洋渐新世晚期，目前仅包含1个已命名物种<i>Kekenodon onamata</i>（凯肯鲸）。<i>Tohoraonepu nihokaiwaiu</i>是一种小型凯肯鲸科新属新种，发现于新西兰南岛奥塔哥地区渐新世晚期（恰特期，Chattian）的科科阿穆绿砂岩（Kokoamu Greensand）中。系统发育分析显示，<i>T. nihokaiwaiu</i>隶属于单系群凯肯鲸科，与暂未命名的凯肯鲸科类群OU 22023构成一个演化支。凯肯鲸科的系统发育位置位于龙王鲸科（Basilosauridae）冠群侧，且隶属于齿状“须鲸类”并系群的干群侧，该类群被排除在新鲸下目（Neoceti）之外。本次分析证实，凯肯鲸科是最晚分化的古鲸类类群，其存续至渐新世晚期。正模标本OU 22394为一具幼年个体，保存有多枚分离的异型齿，具有乳齿特征：包括未矿化的髓腔，以及齿冠低矮呈三角形的颊齿，该特征与所有已知凯肯鲸科类群均不相同。双出牙（diphyodonty）在始新世古鲸类中已有发现，但在地质年代更晚的齿鲸类中尚未被证实；目前学界假设所有新鲸类均为单出牙（monophyodonty）。若<i>T. nihokaiwaiu</i>存在双出牙特征，则这将是鲸类中首个发现于始新世之后地质岩层中的双出牙类群，同时也表明部分渐新世晚期的古鲸类仍保留双出牙特性。

搜集汇总

背景与挑战

背景概述

该数据集提供了关于新发现的晚渐新世小型kekenodontid鲸类'Tohoraonepu nihokaiwaiu'的补充数据，包括系统发育分析矩阵、分支编码列表和多种系统发育树文件。数据集通过详细的古生物学分析，揭示了该物种作为最晚分化的古鲸类，在鲸类进化中的关键位置，并首次暗示了晚于始新世的鲸类中可能存在双牙列性，对理解鲸类牙齿进化具有重要意义。