史前一种不能飞行的鸟类，会在争斗时挥舞翅膀作为武器，这种情景就像武林高手们耍双截棍一样。
耶鲁大学的古生物学家们近日在牙买加发现了朱鹭科鸟类新属奇异朱鹭（Xenicibis）。这种生活在一万年前的鸟类，体型像一只稍大些的鸡，会像挥舞双截棍一样用自己高度特化的翅膀打击对手。相关研究发表在最近的《英国皇家学会会刊B》。
“之前我们从没见过演化出这种结构的动物，”耶鲁大学的N.Longrich说。“除它之外，没有动物能将自己的身体当成‘双截棍’，作为防御敌害的武器。”
研究者们分析了近期发现的奇异朱鹭化石，发现翅膀部分的骨骼非常特殊，具有粗厚、弧形的掌骨。比起一般的不飞鸟，它的胸骨和上肢骨都大得多。于是科学家们猜测，这种结构一定另有用处。
有些鸟类能用翅膀锤击对手，而奇异朱鹭则可以挥舞双翼，用掌骨击打对方，就像两个大沙袋一样。虽然现生朱鹭已经不“流行”这种打斗方式，但它们仍然是领地感非常强的鸟类，经常为筑巢和食物打斗。
因此，很可能，在一万年前，奇异朱鹭如果巢穴或卵受到威胁时，也会使用“双截棍”狠狠地回击入侵者。而在当时的牙买加，蟒蛇和猴子都威胁着的生存，强大的武器确实能派得上用场。
研究小组发现，化石中有两枚翼部骨骼有打斗伤痕：一枚碎裂的掌骨和一根断成两截的肱骨，肱骨的厚度足有一厘米。可见，这种鹭类能够挥动特化的翅膀，用巨大的力量打击对手。
The bizarre wing of the Jamaican flightless ibis Xenicibis xympithecus: a unique vertebrate adaptation
Nicholas R. Longrich and Storrs L. Olson
Birds have frequently evolved to exploit insular environments by becoming adapted to a terrestrial lifestyle and losing the ability to fly, usually via reducing the wings and pectoral girdle. The enigmatic flightless ibis Xenicibis xympithecus (Threskiornithidae) from the Quaternary of Jamaica provides a rare example of flight loss in ibises. We report on previously undescribed fossils of Xenicibis, and show that the wing differed radically from that of all other birds, flightless or volant. The metacarpus is elongate, grotesquely inflated and has extremely thick walls; phalanges are short and block-like; the radius is distally expanded; and the humerus is elongate. The furcula, coracoid and sternum are all well developed. We propose that the elongate forelimb and massive hand functioned in combat as a jointed club or flail. This hypothesis is supported by the morphology of the carpometacarpus, by features permitting rapid extension of the wing and by the presence of fractures in wing bones. Although other birds use the wings as weapons, none resemble Xenicibis, which represents a unique and extraordinary morphological solution to this functional problem. Xenicibis strikingly illustrates how similar selective pressures, acting on a similar starting point, can result in novel outcomes.
