泰国暹罗淡水鳄（Crocodylus siamensis Schneider, 1801）内铸型与骨内迷路的个体发育变化

文献信息

中文摘要

背景： 脑与感觉系统的个体发育变化在塑造脊椎动物的行为表现和生态特化中起重要作用；然而，这些发育途径在濒危鳄类中记录不足。方法：在此，我们首次对东南亚极危物种暹罗淡水鳄（Crocodylus siamensis）整个个体发育过程中的内铸型和骨内迷路发育进行定量分析。我们使用高分辨率计算机断层扫描（CT）和三维重建，检查了代表幼体、亚成体和成体生长阶段的六个头骨。结果：我们的发现揭示了一致的异速生长模式，并与感觉相关神经解剖结构的显著形态变化相关。幼体表现出强烈弯曲的前脑和比例上突出的嗅觉区域，这与其早期依赖化学感觉线索相一致。随着头骨尺寸增加，脑内铸型变得更长、更直，而对应于中脑和后脑的区域显示出与视觉处理和运动协调相关的比例形态变化，提示与视觉处理和运动协调相关区域的个体发育变化。在骨内迷路中也观察到平行的个体发育转变，包括成体lagena尺寸增加和半规管弯曲更明显。这些变化与听觉和前庭功能相关结构的个体发育变异相一致。背侧颅长与内铸型和迷路参数之间的强相关性表明，C. siamensis的感觉相关神经解剖形态遵循一致的个体发育缩放模式。结论：这些发现为理解这种濒危鳄类的感觉生态学建立了重要的神经解剖学基线，并为解释化石鳄类神经解剖学提供了比较框架，对保护生物学、功能形态学和古神经学具有重要意义。

英文摘要

Ontogenetic changes in the brain and sensory systems play an essential role in shaping behavioral performance and ecological specialization in vertebrates; however, these developmental pathways are inadequately recorded in endangered crocodylians. Here, we present the first quantitative analysis of endocast and endosseous labyrinth development across ontogeny in the Siamese freshwater crocodile (Crocodylus siamensis), a critically endangered species from Southeast Asia. Using high-resolution computed tomography (CT) and three-dimensional reconstruction, we examined six skulls representing juvenile, subadult, and adult growth stages. Our findings reveal a consistent pattern of allometric scaling, correlated with marked morphological changes in sensory-related neuroanatomical structures. Juveniles display strongly curved forebrains and proportionally prominent olfactory regions, which is in line with their early reliance on chemosensory cues. As skull size increases, the encephalic endocast becomes longer and straighter, while regions corresponding to the midbrain and hindbrain show proportional morphological changes associated with visual processing and motor coordination, suggesting ontogenetic changes in regions associated with visual processing and motor coordination. Parallel ontogenetic transformations are also observed in the endosseous labyrinth, including increased lagena dimensions and more pronounced semicircular canal curvature in adults. These changes are consistent with ontogenetic variation in structures associated with auditory and vestibular functions. Strong correlations between dorsal cranial length and both endocast and labyrinthine parameters suggest that sensory-related neuroanatomical morphology in C. siamensis follows a consistent ontogenetic scaling pattern. These findings establish an important neuroanatomical baseline for understanding sensory ecology in this endangered crocodilian and provide a comparative framework for interpreting fossil crocodylian neuroanatomy, with implications for conservation biology, functional morphology, and paleoneurology.