Morphological and phylogenetic changes of the hyobranchial apparatus from fishes to basal tetrapods.

下鳃（内脏骨骼）的转变，需要鱼类在水中吸吮进食，以使舌头为基础的陆地进食的装置，是四足动物进化的一个关键方面，但仍然知之甚少。本项目的目的是恢复中晚泥盆世鱼类向四足动物过渡时期下鳃的发育变化。必须解决的几个问题包括：（1）非四足动物的下鳃的哪些结构在基底四足动物中是保守的，（2）哪些结构被修改了，（3）这些动物的不同谱系中下鳃是如何用于进食和呼吸的？该项目将侧重于古生代和中生代基底四足动物及其鱼类亲属的下鳃遗迹的形态和系统发育研究。两个假设将被测试：第一，基础四足动物保留了“鱼一样”的下鳃和喂养的土地上的下巴expression。个体发育改造的下鳃与阐述一个可移动的舌头骨骼进化后期，独立的血统导致lissampibians和tagiotes。第二，在四足动物历史的早期，支持舌的下鳃的个体发育重塑就已经进化，保留“鱼样”下鳃是一种幼态特征。对下鳃的系统发育变化有更好的了解，将大大提高我们对鱼类向四足动物转变和脊椎动物陆生起源的理解。

The transformation of the hyobranchium (visceral skeleton) that requires fishes to suction feeding in water, to an apparatus that enables tongue-based terrestrial feeding, is a key aspect of the evolution of tetrapods, but is still poorly understood. The goal of this project is to recover the developmental changes of the hyobranchium during the fish-to-tetrapod transition in the Middle and Late Devonian. Several questions must be addressed including, (1) which structures of the hyobranchium of nontetrapods were conserved in basal tetrapods, (2) which were modified, and (3) how was the hyobranchium used for feeding and breathing in the different lineages of these animals? The project will focus on the morphological and phylogenetic investigation of the hyobranchial remains of Palaeozoic and Mesozoic basal tetrapods and their fish-like relatives. Two hypotheses will be tested: First, basal tetrapods retained a "fish-like" hyobranchium and fed on land by jaw prehension. Ontogenetic remodelling of the hyobranchium with the elaboration of a movable tongue skeleton evolved later in evolution, independently in the lineage leading to lissamphibians and to amniotes. Second, ontogenetic remodelling for a tongue-supporting hyobranchium evolved early in tetrapod history, and the retention of a "fish-like" hyobranchium is a paedomorphic trait. The better knowledge of phylogenetic changes of the hyobranchium would greatly improve our understanding of the fish-totetrapod transition and the origin of terrestriality in vertebrates.