Witton Mark P, Naish Darren
School of Earth and Environmental Sciences, University of Portsmouth, Portsmouth, United Kingdom.
PLoS One. 2008 May 28;3(5):e2271. doi: 10.1371/journal.pone.0002271.
Azhdarchid pterosaurs were among the most widespread and successful of pterosaur clades, but their paleoecology remains controversial. Morphological features common to all azhdarchids include a long, shallow rostrum; elongate, cylindrical cervical vertebrae that formed a long and unusually inflexible neck; and proportionally short wings with an abbreviated fourth phalanx. While azhdarchids have been imagined as vulture-like scavengers, sediment probers, swimmers, waders, aerial predators, or stork-like generalists, most recent authors have regarded them as skim-feeders, trawling their lower jaws through water during flight and seizing aquatic prey from the water's surface. Although apparently widely accepted, the skim-feeding model lacks critical support from anatomy and functional morphology. Azhdarchids lack the many cranial specialisations exhibited by extant skim-feeding birds, most notably the laterally compressed lower jaw and shock absorbing apparatus required for this feeding style. Well-preserved azhdarchid skulls are rare, but their rostra and lower jaws appear to have been sub-triangular in cross-section, and thus dissimilar to those of skim-feeders and sediment probers. Taphonomic data indicates that azhdarchids predominately inhabited inland settings, and azhdarchid morphology indicates that they were poorly suited for all proposed lifestyles bar wading and terrestrial foraging. However, azhdarchid footprints show that their feet were relatively small, padded and slender, and thus not well suited for wading. We argue that azhdarchids were stork- or ground hornbill-like generalists, foraging in diverse environments for small animals and carrion. Proficient terrestrial abilities and a relatively inflexible neck are in agreement with this interpretation.
阿氏翼龙是翼龙类中分布最广、最成功的类群之一，但其古生态学仍存在争议。所有阿氏翼龙共有的形态特征包括一个长而浅的吻部；细长的圆柱形颈椎，形成了一个长且异常僵硬的脖子；以及比例上较短的翅膀，其第四指骨缩短。虽然阿氏翼龙曾被想象为类似秃鹫的食腐动物、沉积物探测者、游泳者、涉禽、空中捕食者或类似鹳的通才，但最近的大多数作者认为它们是掠过式捕食者，在飞行过程中将下颌拖过水面并从水面抓取水生猎物。尽管掠食模型显然已被广泛接受，但它缺乏来自解剖学和功能形态学的关键支持。阿氏翼龙缺乏现存掠过式捕食鸟类所具有的许多颅骨特化特征，最明显的是这种捕食方式所需的侧向压缩的下颌和减震装置。保存完好的阿氏翼龙头骨很少见，但它们的吻部和下颌在横截面看来似乎是亚三角形的，因此与掠过式捕食者和沉积物探测者的不同。埋藏学数据表明，阿氏翼龙主要栖息在内陆环境中，而阿氏翼龙的形态表明，除了涉禽和陆地觅食外，它们不太适合所有提出的生活方式。然而，阿氏翼龙的足迹表明它们的脚相对较小、有肉垫且细长，因此不太适合涉禽生活。我们认为阿氏翼龙是类似鹳或地犀鸟的通才，在不同环境中觅食小动物和腐肉。熟练的陆地能力和相对僵硬的脖子与这种解释相符。
