近日，瑞典乌普萨拉大学Per E. Ahlberg及其研究团队的研究认为最早的羊膜动物足迹重新校准了四足动物进化的时间轴。2025年5月14日出版的《自然》杂志发表了这项成果。

在这里，课题组提出了来自澳大利亚的新的轨道数据，挑战了这个被广泛接受的时间表。一块来自陶古隆地区维多利亚雪原地层的有脚印的石板，可以确定地追溯到公元前8、9世纪早期，上面显示了一种有爪足的冠群羊膜动物的脚印，很可能是一种原始的蜥脚类动物。这将冠类羊膜动物的可能起源往回推了至少3500万到4000万年。

该团队还将Notalacerta的范围扩展到早石炭纪。亚特拉纪径迹表明，羊膜动物冠群节点不可能比泥盆系/石炭系界线年轻很多，四足动物冠群节点可能位于泥盆系深处；根据分子树枝长度的估计，后者的年龄大约在早期弗拉斯尼亚。这对四足动物的早期进化意义深远；所有茎-四足动物和茎-羊膜动物谱系都起源于泥盆纪。似乎四足动物的进化速度要快得多，泥盆纪的四足动物记录比人们认为的要不完整得多。

据了解，已知的冠群羊膜动物化石记录始于石炭纪晚期，有蜥脚类的足迹制造者Notalacerta和蜥脚类的身体化石Hylonomthem。冠群四足动物最早的体化石为中石炭世，最古老的足迹为早石炭世。提示四足动物冠群起源于石炭世早期，羊膜动物冠群出现于石炭世晚期早期。

附：英文原文

Title: Earliest amniote tracks recalibrate the timeline of tetrapod evolution

Author: Long, John A., Niedwiedzki, Grzegorz, Garvey, Jillian, Clement, Alice M., Camens, Aaron B., Eury, Craig A., Eason, John, Ahlberg, Per E.

Issue&Volume: 2025-05-14

Abstract: The known fossil record of crown-group amniotes begins in the late Carboniferous with the sauropsid trackmaker Notalacerta1,2 and the sauropsid body fossil Hylonomus1,2,3,4. The earliest body fossils of crown-group tetrapods are mid-Carboniferous, and the oldest trackways are early Carboniferous5,6,7. This suggests that the tetrapod crown group originated in the earliest Carboniferous (early Tournaisian), with the amniote crown group appearing in the early part of the late Carboniferous. Here we present new trackway data from Australia that challenge this widely accepted timeline. A track-bearing slab from the Snowy Plains Formation of Victoria, Taungurung Country, securely dated to the early Tournaisian8,9, shows footprints from a crown-group amniote with clawed feet, most probably a primitive sauropsid. This pushes back the likely origin of crown-group amniotes by at least 35–40 million years. We also extend the range of Notalacerta into the early Carboniferous. The Australian tracks indicate that the amniote crown-group node cannot be much younger than the Devonian/Carboniferous boundary, and that the tetrapod crown-group node must be located deep within the Devonian; an estimate based on molecular-tree branch lengths suggests an approximate age of early Frasnian for the latter. The implications for the early evolution of tetrapods are profound; all stem-tetrapod and stem-amniote lineages must have originated during the Devonian. It seems that tetrapod evolution proceeded much faster, and the Devonian tetrapod record is much less complete, than has been thought.

DOI: 10.1038/s41586-025-08884-5

Source: https://www.nature.com/articles/s41586-025-08884-5