Aerodynamic reconstruction of the primitive fossil bat Onychonycteris finneyi (Mammalia: Chiroptera)
Aerodynamic reconstruction of the primitive fossil bat Onychonycteris finneyi (Mammalia: Chiroptera)
复制标题
DOI：
10.1098/rsbl.2018.0857
复制
发表时间：
2019-03-01
期刊：
影响因子：
3.3
通讯作者：
Giannini, Norberto P.
中科院分区：
文献类型：
--
作者：
Amador, Lucila I.;Simmons, Nancy B.;Giannini, Norberto P.
蝙蝠是唯一能够进行动力飞行的哺乳动物。从完整的骨骼中已知的最古老的蝙蝠之一是始新世早期(怀俄明州格林河组，52.5 Ma)的Onychonicteris finneyi蝙蝠。据估计，它的重量约为40克，它展示了迄今已知的蝙蝠最原始的特征组合。在这里，我们重建了两个已知标本的机翼，计算了基本的空气动力学变量，并将它们与现存的蝙蝠和滑翔哺乳动物的翼型进行了比较。甲壳类出现在蝙蝠形态空间的边缘，突显出其飞行装置的原始形态。与任何现存的蝙蝠相比，这种灭绝物种的空气动力学效率较低。当我们在一个不包括手翼的甲壳动物模型中估计机翼变量时，它接近于现存滑翔哺乳动物的形态空间。在没有这种结构的模型上增加一个手翼，使得展弦比增加了2.3倍，机翼载荷减少了28%，从而大大增强了空气动力学。在这些模型的背景下，翼手翼通过基因调节的发育变化而快速进化，似乎是早期蝙蝠从滑行到拍打的假想转变的关键转变。
Bats are the only mammals capable of powered flight. One of the oldest bats known from a complete skeleton is Onychonycteris finneyi from the Early Eocene (Green River Formation, Wyoming, 52.5 Ma). Estimated to weigh approximately 40 g, Onychonycteris exhibits the most primitive combination of characters thus far known for bats. Here, we reconstructed the aerofoil of the two known specimens, calculated basic aerodynamic variables and compared them with those of extant bats and gliding mammals. Onychonycteris appears in the edges of the morphospace for bats, underscoring the primitive conformation of its flight apparatus. Low aerodynamic efficiency is inferred for this extinct species as compared to any extant bat. When we estimated aerofoil variables in a model of Onychonycteris excluding the handwing, it closely approached the morphospace of extant gliding mammals. Addition of a handwing to the model lacking this structure results in a 2.3-fold increase in aspect ratio and a 28% decrease in wing loading, thus greatly enhancing aerodynamics. In the context of these models, the rapid evolution of the chiropteran handwing via genetically mediated developmental changes appears to have been a key transformation in the hypothesized transition from gliding to flapping in early bats.