Gibson Sarah Z
Department of Geology and Biodiversity Institute, University of Kansas, 1345 Jayhawk Boulevard, Lawrence, KS, 66045, USA,
Naturwissenschaften. 2015 Apr;102(3-4):10. doi: 10.1007/s00114-015-1262-y. Epub 2015 Feb 17.
Fishes have evolved to exploit multiple ecological niches. Extant fishes in both marine (e.g., rabbitfishes, surgeonfishes) and freshwater systems (e.g., haplochromine cichlids, characiforms) have evolved specialized, scoop-like, multidenticulate teeth for benthic scraping, feeding primarily on algae. Here, I report evidence of the oldest example of specialized multidenticulate dentition in a ray-finned fish, †Hemicalypterus weiri, from the Upper Triassic Chinle Formation of southeastern Utah (∼210-205 Ma), USA. †H. weiri is a lower actinopterygian species that is phylogenetically remote from modern fishes, and has evolved specialized teeth that converge with those of several living teleost fishes (e.g., characiforms, cichlids, acanthurids, siganids), with a likely function of these teeth being to scrape algae off a rock substrate. This finding contradicts previously held notions that fishes with multicuspid, scoop-like dentition were restricted to teleosts, and indicates that ray-finned fishes were diversifying into different trophic niches and exploring different modes of feeding earlier in their history than previously thought, fundamentally altering our perceptions of the ecological roles of fishes during the Mesozoic.
鱼类已经进化以利用多种生态位。现存于海洋（如兔鱼、刺尾鱼）和淡水系统（如帚齿丽鱼科丽鱼、脂鲤科鱼类）中的鱼类已经进化出专门的、勺状的、多齿的牙齿用于底栖刮食，主要以藻类为食。在此，我报告了来自美国犹他州东南部上三叠统钦尔组（约2.1亿 - 2.05亿年前）的辐鳍鱼†韦氏半鳍鱼（†Hemicalypterus weiri）中最古老的专门多齿齿列的证据。†韦氏半鳍鱼是一种低等辐鳍鱼类，在系统发育上与现代鱼类相距甚远，并且已经进化出与几种现存硬骨鱼类（如脂鲤科鱼类﹑丽鱼科鱼类﹑刺尾鱼科鱼类﹑蓝子鱼科鱼类）的牙齿趋同的专门牙齿，这些牙齿的可能功能是从岩石基质上刮下藻类。这一发现与之前认为具有多尖、勺状齿列的鱼类仅限于硬骨鱼类的观念相矛盾，并表明辐鳍鱼类在其历史上比之前认为的更早地分化为不同的营养生态位并探索不同的摄食方式，从根本上改变了我们对中生代鱼类生态作用的认知。
