Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences (CAS), Beijing 100044, China.
CAS Center for Excellence in Life and Paleoenvironment, Beijing 100101, China.
Science. 2022 Jun 3;376(6597):eabl8316. doi: 10.1126/science.abl8316.
The long neck of the giraffe has been held as a classic example of adaptive evolution since Darwin's time. Here we report on an unusual fossil giraffoid, , from the early Miocene, which has an unusual disk-shaped headgear and the most complicated head-neck joints in known mammals. The distinctive morphology and our finite element analyses indicate an adaptation for fierce head-butting behavior. Tooth enamel isotope data suggest that occupied a niche different from that of other herbivores, comparable to the characteristic high-level browsing niche of modern giraffes. The study shows that giraffoids exhibit a higher headgear diversity than other ruminants and that living in specific ecological niches may have fostered various intraspecific combat behaviors that resulted in extreme head-neck morphologies in different giraffoid lineages.
长颈鹿的长脖子自达尔文时代以来一直被视为适应性进化的经典范例。在这里，我们报告了一种来自早中新世的不寻常的长颈鹿化石，它有一个不寻常的盘状头饰和已知哺乳动物中最复杂的头颈关节。独特的形态和我们的有限元分析表明，它适应了激烈的头部撞击行为。牙齿珐琅质同位素数据表明，这种长颈鹿类动物占据了一个与其他食草动物不同的生态位，类似于现代长颈鹿特有的高水平觅食生态位。该研究表明，长颈鹿类动物的头饰多样性比其他反刍动物更高，生活在特定的生态位可能促进了各种种内战斗行为，导致不同长颈鹿类群的头颈部形态极端化。
