Autostyly, defined by fusion of the palatoquadrate to the neurocranium and loss of the hyomandibula as a suspensory element, is a hallmark of lungfish cranial organization among sarcopterygians, yet its evolutionary origin remains incompletely understood. This study elucidates this transition through a detailed comparative analysis of the palatoquadrate and its articulations in three sequentially diverging stem dipnoans: Youngolepis, Diabolepis, and the earliest eudipnoan Paleolophus. Youngolepis exhibits a reoriented palatoquadrate, indicating functional reorganization of jaw mechanics prior to autostyly. In Diabolepis, reduction of the pars autopalatina and retention of a primitive suborbital articulation suggest further modification of jaw suspension. Paleolophus documents the earliest unambiguous autostyly, with direct palatoquadrate-neurocranial integration preceding complete fusion with the lateral commissure, along with an enlarged adductor fossa. Comparison with Middle and Late Devonian lungfishes indicates that full autostyly was achieved only after the development of a robust, integrated otic process. These results demonstrate that lungfish autostyly evolved stepwise, driven by increasing biomechanical demands associated with durophagous feeding.

自接型颌骨是肺鱼类头部骨骼的一个重要特征，但其起源演化尚未完全明晰。对肺鱼类干群三个重要代表——杨氏鱼(Youngolepis)、奇异鱼(Diabolepis)以及最早的真肺鱼古嵴鱼(Paleolophus)——的腭方骨及其关节结构进行了详细的比较解剖学研究，揭示了这一重要特征的递进式演化过程。杨氏鱼的腭方骨后部接近垂直，表明在自接型颌骨形成之前，其颌骨的力学功能已经发生重组。在奇异鱼中，颌骨连接结构进一步演化：腭方骨的自腭部分明显缩减，但保留了原始的眶下关节。古嵴鱼是最原始的真肺鱼类，也是具有肺鱼自接型颌骨的最早化石代表。其腭方骨与脑颅愈合，但尚未与侧联合骨完全融合。中、晚泥盆世的肺鱼进一步演化出强壮且与侧联合愈合的耳突，标志着自接型颌骨的最终形成。这些结果表明，肺鱼的自接型颌骨是在与食壳性取食相关的生物力学驱动下逐步演化形成的。