《自然》杂志对已灭绝爬行动物Captorhinus的研究表明，口颊呼吸向肋骨辅助呼吸的转变很可能与最早动物上陆的时间同步，至少发生在2.9亿年前。该转变降低了口颊呼吸对头颈形态的限制，提高了氧气摄入效率（并弱化了依赖皮肤被动补氧的机制），并推动了爬行动物快速多样化，最终导致其后续在约1亿年以上的生态主导（主要体现在恐龙时代）。

软组织（如肺、肌肉、软骨）通常在死亡后迅速腐败，但俄克拉荷马州Richards Spur的洞穴环境因含油、干燥及低氧和细沉积封闭而使标本木乃伊化。两个Captorhinus个体在该环境中得以保存，油染和岩层包裹的化石经CT扫描显示其具有柔韧的软骨胸骨，可使肋骨、肋肌与肩带协同，使躯干进行进气与呼气。

该结果还显示肩带已完整并入呼吸系统，这对于早期陆生步行动物尤其关键，因为肩带一方面支撑体重，另一方面提供行走所需的骨骼力量。该发现支持长期假设：陆行与呼吸演化高度耦合；但“先行走后呼吸”还是“先呼吸后行走”仍未定论。

A Nature study of extinct reptiles, including the genus Captorhinus, indicates that the shift from cheek-based breathing to rib-assisted breathing likely occurred at the same time as the first animals moved onto dry land, at least 290 million years ago. This shift reduced constraints from cheek-driven respiration, improved oxygen intake efficiency compared with skin-compensated breathing, and enabled rapid reptile diversification that culminated in dinosaur-dominated dominance for over 100 million years.

Soft tissues central to breathing, such as lungs, muscles, and cartilage, usually decay quickly, but the Richards Spur caves in Oklahoma created a preservative setting through petroleum, aridity, and fine sediment limiting oxygen access. Two Captorhinus individuals were preserved there, and CT scans of the oil-stained, rock-embedded fossils revealed a flexible cartilage sternum linking ribs, rib muscles, and the shoulder girdle to pump air in and out of the torso.

This integration of the shoulder girdle is especially significant because that bony structure would also bear body weight and provide propulsion for early terrestrial locomotion. The finding supports a long-standing hypothesis that early tetrapod terrestrial movement and respiration evolved together, while the exact sequence of first movement versus first rib breathing remains unresolved.

Source: Mummified reptiles are revealing how breathing evolved

Subtitle: The question had previously been up in the air

Dateline: 4月 09, 2026 04:30 上午