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Tinirau (genus)
''Tinirau'' is an extinct genus of sarcopterygian fish from the Middle Devonian of Nevada. Although it spent its entire life in the ocean, ''Tinirau'' is a stem tetrapod close to the ancestry of land-living vertebrates in the crown group Tetrapoda. Relative to more well-known stem tetrapods, ''Tinirau'' is more closely related to Tetrapoda than is ''Eusthenopteron'', but farther from Tetrapoda than is ''Panderichthys''. The type and only species of ''Tinirau'' is ''T. clackae'', named in 2012.
== Description ==
''Tinirau'' shares many advanced features with later tetrapodomorphs in the pelvic limb bones and glenoids (shoulder sockets). By the time ''Tinirau'' appeared, many stem tetrapods had already developed the three major hindlimb bones of tetrapods: the femur, tibia, and fibula. While derived stem tetrapods like ''Panderichthys'' had hindlimb configurations very similar to the first land-living tetrapods, some early forms such as ''Eusthenopteron'' possessed a prominent postaxial process of the fibula hanging over the fibulare bone below it. ''Tinirau'' is the earliest known stem tetrapod to have a significantly reduced postaxial process, and a fibula more like those of later tetrapods.〔
Like those of the Late Devonian ''Panderichthys'' and ''Ichthyostega'', the glenoid of ''Tinirau'' is elongated along the anteroposterior (forward-backward) axis of the body. The lengthening of the glenoid corresponds with a flattening of the proximal end of the humerus, a feature common in the forelimbs of more advanced stem tetrapods. Although the pectoral limb bones and girdle were not strong enough to support the weight of ''Tinirau'' out of water, glenoid lengthening and other changes to the proximal forelimb were among the first steps in the transformation from pectoral fin to forelimb.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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