State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing 210008, China.
Department of Earth Sciences, The University of Hong Kong, Hong Kong Special Administrative Region, China.
Sci Rep. 2017 Mar 20;7:44932. doi: 10.1038/srep44932.
Courtship behaviours, frequent among modern insects, have left extremely rare fossil traces. None are known previously for fossil odonatans. Fossil traces of such behaviours are better known among the vertebrates, e.g. the hypertelic antlers of the Pleistocene giant deer Megaloceros giganteus. Here we describe spectacular extremely expanded, pod-like tibiae in males of a platycnemidid damselfly from mid-Cretaceous Burmese amber. Such structures in modern damselflies, help to fend off other suitors as well as attract mating females, increasing the chances of successful mating. Modern Platycnemidinae and Chlorocyphidae convergently acquired similar but less developed structures. The new findings provide suggestive evidence of damselfly courtship behaviour as far back as the mid-Cretaceous. These data show an unexpected morphological disparity in dancing damselfly leg structure, and shed new light on mechanisms of sexual selection involving intra- and intersex reproductive competition during the Cretaceous.
求偶行为在现代昆虫中很常见，但在化石中留下的痕迹却极为罕见。以前在有翅目化石中还没有发现这种行为的化石痕迹。在脊椎动物中，这种行为的化石痕迹更为常见，例如更新世巨型鹿（Megaloceros giganteus）的特化鹿角。在这里，我们描述了从中生代缅甸琥珀中发现的一种 platynemidid 豆娘雄性的壮观的极度扩展的豆荚状胫骨。在现代豆娘中，这种结构有助于击退其他求偶者，吸引交配的雌性，从而增加成功交配的机会。现代的 Platynemidinae 和 Chlorocyphidae 趋同地获得了类似但不太发达的结构。新的发现为中白垩世以来的豆娘求偶行为提供了有说服力的证据。这些数据显示了跳舞豆娘腿部结构在形态上的出人意料的差异，并为涉及有翅目生殖竞争的性选择机制提供了新的认识，这种竞争在白垩纪时期涉及到雌雄个体之间的生殖竞争。
