Osteology, phylogeny, and higher classification of the fishes of the order Plectognathi (Tetraodontiformes) /

Occipito‐vertebral fusion in ocean sunfishes (Teleostei: Tetraodontiformes: Molidae) and its phylogenetic implications

“…In later development, they articulate with the exoccipitals exactly as they do in most tetraodontiforms (see Tyler, 1980). This led to Tyler's confusion of the first vertebra with the posterior end of the basioccipital and his erroneous statement that the "exoccipital does not articulate with the first vertebra.…”

“…Similarly, Raven (1939a) and Tyler (1980) reported 8 abdominal and 8 caudal vertebrae in Masturus, but it has actually 9 ϩ 8, as evidenced by our two developmental stages.…”

“…Vertebral counts for Mola mola were reported as 8 abdominal plus 8 caudal by Cleland (1862), Steenstrup and Lü tken (1898), and Kaschkaroff (1914), but Tyler (1980) reported 8 ϩ 9 in his two specimens. Because of the occipito-vertebral fusion, Mola actually has 9 abdominal vertebrae.…”

“…Raven (1939b) and Tyler (1980) reported 8 abdominal and 10 caudal vertebrae for Ranzania laevis, but FraserBrunner (1951) provided a count of 8 abdominal and a range of 10 or 11 caudal vertebrae in his key, without indicating the source or basis for this count. Whatever the number of caudal vertebrae, Ranzania has 9, not 8, abdominal vertebrae.…”

“…Because of their unique appearance, ocean sunfishes have fascinated naturalists and scientists for centuries. Although the earliest anatomical descriptions date from the 1800s (Meckel, 1828;Wellenbergh, 1840;Goodsir, 1841;Cleland, 1862;Steenstrup and Lü tken, 1898) and several monographs appeared in the 20th century (Gregory and Raven, 1934;Raven, 1939a,b;Winterbottom, 1974;Tyler, 1980), much of the unusual, highly derived anatomical structure of molids is still poorly understood. During our study of the development and homology of the molid clavus or pseudocaudal fin Johnson and Britz, 2004), we discovered a previously overlooked and highly unusual character of the vertebral column that characterizes the Molidae: ontogenetic fusion of the first vertebra with the occiput.…”