近日，里约热内卢国家博物馆的古生物学家们在巴西东北部发现一种14米长，有三排牙齿的凶猛食肉恐龙，这种牙齿结构是兽脚亚目恐龙里独一无二的。它被命名为歌伦波奥沙拉龙（Oxalaiaquilombensis），生活在9500万年前。相关文章发表在《巴西科学院年鉴》（Annals of the Brazilian Academy of Sciences）。
奥沙拉龙一般只使用最前排的牙齿，后面两排正在发育的牙齿可替换前面磨损或掉落的牙齿，这种现象在鲨鱼和某些爬行动物中很常见，但在兽脚类恐龙中还是头一次。
奥沙拉龙属于一种棘背龙（spinosaurids），它的吻端狭长，很像鳄鱼。有趣的是，它似乎与北非出土的那些棘背龙亲缘关系更近，跟巴西的其它棘背龙反而疏远些。因此我们可以推断，这些棘背龙的祖先早在1.3-1.1亿年前，非洲和南美大陆分开时，就已经出现了，随着大陆漂移，棘背龙的祖先分隔两岸，走上了独立的演化道路。（生物谷Bioon.com）
生物谷推荐原文出处：
An. Acad. Bras. Ciênc. [online]. 2011, vol.83, n.1, pp. 99-108. ISSN 0001-3765.
A new dinosaur (Theropoda, Spinosauridae) from the Cretaceous (Cenomanian) Alcantara Formation, Cajual Island, Brazil.
KELLNER, Alexander WA. et al.
A new spinosaurid taxon, Oxalaia quilombensis gen. et sp. nov., is described based on the anterior part of a snout and a fragment of a maxilla. These specimens were collected at the Laje do Coringa site, Late Cretaceous (Cenomanian) of the S?o Luis Basin. Unlike Cristatusaurus and Suchomimus, Oxalaia quilombensis lacks serrations on the teeth. The new species differs from Angaturama limai by having the anterior part of the premaxillae more expanded and by lacking a sagittal premaxillary crest. It further differs from Spinosaurus cf. S. aegyptiacus and the Algerian spinosaurid by the rounder shape of the terminal expansion. Furthermore, xalaia quilobensis has one functional tooth followed by two replacement teeth, a feature not previously observed in theropods. Oxalaia quilombensis appears to be more closely related to the spinosaurids found in North Africa than to the Brazilian members of this clade and thus further increases the diversity of these enigmatic predatory dinosaurs in this country.
Keywords : Dinosauria; Spinosauridae; Oxalaia quilombensis; Cenomanian; Brazil.
