大象以强烈偏侧的躯干行为而闻名,但是对推动大象偏侧化的机制知之甚少。这里,我们调查了可能促进偏侧化的大象嘴组织的特征。我们发现大象的下颚宽度很窄,但是甚至在颌骨之外被强烈地拉长。象唇触须逐渐变长。因此,大象有两个侧向密集,短的微vibrissae阵列和中央,密度较小的长大型夹生。这是祖先哺乳动物面部触感模式的倒置,在中央,密集的短微vibrisae两侧是两个侧向大vibrisae阵列。象微病毒的卵泡比大型病毒小。类似于树干尖端vibrissae,象唇微vibrisae显示横向不对称磨损。对亚洲动物园大象的观察表明,偏侧喂养导致偏侧磨损。看来,祖先哺乳动物的嘴(上唇和下唇,门牙,额叶微vibrisae)是通过口服食物理解而形成的。大象嘴的组织发生了根本性的变化,然而,因为树干介导的喂养取代了口服忧虑。这种大象的嘴巴变化包括上唇鼻融合到躯干,超灵活的细长下颚,门牙的丢失,和侧面而不是正面的微振动。大象对侧向食物插入的专业化反映在口腔食物忧虑和嘴唇触感模式的居中作用的减少上。
Elephants are known for strongly lateralized trunk behaviors, but the mechanisms driving elephant lateralization are poorly understood. Here, we investigate features of elephant mouth organization that presumably promote lateralization. We find the lower jaw of elephants is of narrow width, but is rostrally strongly elongated even beyond the jaw bone. Elephant lip
vibrissae become progressively longer rostrally. Thus, elephants have two lateral dense, short microvibrissae arrays and central, less dense long macrovibrissae. This is an inversion of the ancestral mammalian facial
vibrissae pattern, where central, dense short microvibrissae are flanked by two lateral macrovibrissae arrays. Elephant microvibrissae have smaller follicles than macrovibrissae. Similar to trunk-tip
vibrissae, elephant lip microvibrissae show laterally asymmetric abrasion. Observations on Asian zoo elephants indicate lateralized abrasion results from lateralized feeding. It appears that the ancestral mammalian mouth (upper and lower lips, incisors, frontal microvibrissae) is shaped by oral food apprehension. The elephant mouth organization radically changed, however, because trunk-mediated feeding replaced oral apprehension. Such elephant mouth changes include the upper lip-nose fusion to the trunk, the super-flexible elongated lower jaw, the loss of incisors, and lateral rather than frontal microvibrissae. Elephants\' specialization for lateral food insertion is reflected by the reduction in the centering effects of oral food apprehension and lip
vibrissae patterns.