ABSTRACT

Recent research on mysticete fossils from the Late Eocene and Oligocene has revolutionised our understanding of the diversity and evolutionary scenarios for early baleen whales. For example, aetiocetids are a possible, though controversial, lineage that bridges the gap between the toothed and baleen-bearing mysticetes, and eomysticetids show a further transitional step towards the baleen-bearing status, with the presence of non-functional dentition in adults. However, information about the origin of crown mysticetes, including the most recent common ancestor of all extant lineages and its descendants, is critical to further understanding the evolution of baleen whales. The phylogenetic positions of the Oligocene Toipahautea, Whakakai, Horopeta, and Mauicetus from New Zealand remain unresolved and problematic, but all four genera show a close relationship with crown mysticetes. The original and subsequent cladistic analyses have consistently revealed a sister relationship between the Toipahautea-to-Mauicetus grade and crown mysticetes, and Horopeta has been placed close to the cetotheriids within the crown group. This review aims to stimulate more research on this topic by elucidating the origin of crown mysticetes, which likely experienced a poorly known radiation event during the Oligocene that established the modern lineages.

摘要

最近对始新世晚期和渐新世的须鲸化石的研究彻底改变了我们对早期须鲸多样性和进化情景的理解。例如，虽然有争议，但甲鲸科是一个可能的谱系，它弥补了有齿须鲸和须须鲸之间的差距，而鲸须鲸则显示出向鲸须状态的进一步过渡，成年鲸中存在非功能性牙列。然而，有关冠须鲸起源的信息，包括所有现存谱系及其后代的最新共同祖先，对于进一步了解须鲸的进化至关重要。渐新世Toipahautea、Whakakai、Horopeta和来自新西兰的Mauicetus仍未解决且存在问题，但所有四个属都显示出与冠须鲸的密切关系。最初的和随后的分支分析一致揭示了Toipahautea- to -Mauicetus级别和冠须兽之间的姐妹关系，而Horopeta被放置在冠组内靠近鲸齿兽的位置。本综述旨在通过阐明冠须鲸的起源来激发对此主题的更多研究，冠须鲸可能在渐新世期间经历了一次鲜为人知的辐射事件，从而建立了现代谱系。