Department of Biology, Adelphi University, 1 South Avenue, Garden City, NY 11530, USA.
Curr Biol. 2023 May 8;33(9):R349-R350. doi: 10.1016/j.cub.2023.02.067.
The long-necked dinosaurs, sauropods, are famous for their extreme body sizes, evolving body masses several times greater than the next-heaviest terrestrial animals, elephant-like and rhinoceros- like mammals and 'duck-billed' dinosaurs. The pace of sauropod discovery has been exponential in recent decades, resulting in the recognition of sauropods as a global, ecologically diverse group of herbivorous dinosaurs comprising over 250 known species. However, limitations due to missing data from their patchy fossil record have so far limited studies of sauropod body-size evolution to less than half their known diversity. Here, I present models to confidently predict unknown limb-bone measurements in sauropods, resulting in a dataset 50% larger than previously assembled. Leveraging the emerging consilience among body mass estimation methods for fossil tetrapods, I then map sauropod body mass evolution through time in a phylogenetic context. Likelihood-based ancestral state reconstruction reveals that sauropods convergently surpassed maximum terrestrial mammalian body mass at least three dozen times over the course of 100 million years, on at least six landmasses and in at least five ecomorphologically disparate clades. Sauropod maximum body mass rapidly increased early in their evolutionary history from under 5,000 kg before levelling off around 40,000 kg (with notable exceptions), in a pattern similar to that observed in terrestrial mammals.
长颈恐龙，蜥脚类恐龙，以其极端的体型而闻名，它们的身体质量进化到比下一个最重的陆地动物，如大象和犀牛一样的哺乳动物和“鸭嘴”恐龙还要大好几倍。近几十年来，蜥脚类恐龙的发现速度呈指数级增长，这使得人们认识到蜥脚类恐龙是一个具有全球生态多样性的草食性恐龙群体，由超过 250 个已知物种组成。然而，由于其化石记录中缺失数据的限制，迄今为止，对蜥脚类恐龙体型进化的研究仅限于其已知多样性的一半以下。在这里，我提出了模型，可以自信地预测蜥脚类恐龙未知的肢骨测量值，从而得到一个比以前组装的数据集大 50%的数据集。利用化石四足动物体重估计方法之间正在出现的一致性，我在系统发育背景下绘制了蜥脚类恐龙的体重进化。基于可能性的祖先状态重建表明，蜥脚类恐龙在 1 亿年的时间里至少有 30 次超过了最大陆地哺乳动物的体重，至少在 6 个陆地上，并且在至少 5 个生态形态上不同的分支中都有这种情况。蜥脚类恐龙的最大体重在其进化历史的早期迅速增加，从不到 5000 公斤增加到 40000 公斤左右（有明显的例外），这一模式与陆地哺乳动物的观察结果相似。
