part of start stage end stage caudal fin skeleton vertebra ural vertebra Vertebrae that are posterior to the preural vertebrae. There is disagreement whether the diural interpretation or polyural interpretation of the caudal skeleton is what is observed in zebrafish. These two interpretations lead to differences in counting the ural vertebrae. Diural interpretations consider the basic bauplan of the caudal fin to be composed of an anterior centrum (preural centrum 1 + ural centrum 1) supporting the parhypural and hypurals 1 and 2 and a posterior centrum supporting hypurals 3 -5 or 3-6 with variations in hypural number due to fusion or loss. From the polyural perspective, the teleost caudal fin is considered an evolutionary derivation of a fully metameristic caudal fin in which each hypural is supported by a single ural centrum with its own neural arch. ZFA:0005959 zfinf zebrafish_anatomy 2024-08-15T12:42:50Z larval:protruding-mouth adult