突吻鲸的吻一般形似海豚，并不短钝，它们通常会潜入几百米或更深的海里追逐鱿鱼、鱼类和其它猎物。但新发现的化石新证据显示，这类齿鲸的祖先种类中至少有一类被称为喙鲸科的物种是在水表附近游戈猎食的。去年在秘鲁西南沿海海岸出土的这些化石是第一只同其假设的猎物的化石一起出土的齿鲸，研究人员说。岩石中出土的其它化石显示，在大约990万年至880万年前，那些裹葬这只鲸鱼(见上图，艺术家复原再现的Messapicetus gregarius)的部分遗骸的岩石积聚形成了海底沉淀物。如果不是在这只鲸鱼的胸腔内和头部附近发现保存有大量像沙丁鱼的鱼类，这些鲸鱼遗骸不会引起这么大的关注。研究人员今天在《皇家学院B院刊》在线版上报告称，因为这些小鱼的鱼鳞片没有曾暴露在胃酸中的迹象，所以鲸鱼一定是在死前不久刚食用了这些小鱼，然后一起沉入海底。那个水域的岩石很少保存有此类小鱼的鱼鳞，因此研究人员提出，那些小鱼(很可能和它们当代的同类一样在洋面或靠近洋面的水域捕食)可能是这只鲸鱼“最后的晚餐”的化石，由于鲸鱼的内脏腐烂膨胀，它们被挤出了鲸鱼的尸体之外。这只鲸鱼的最后一餐大约包含有40至60条平均长度在39厘米、总重量在16至25公斤的鱼，这和它那些体型相似的当代近亲饱餐一顿的量相差无几。新发现有助于对突吻鲸的进化及其竞争环境提供线索：M. gregarius在该地区海域畅游后不久，海豚就出现了，它们在浅海水域的成功(现在海豚是浅海水域的霸主)可能导致喙鲸科的鲸鱼们放弃了在洋面水域觅食。

    原文链接：Ancient whale fossilized with its last meal

    原文摘要：Beaked whales, which often have dolphinlike snouts rather than blunt muzzles, typically dive hundreds of meters or more to chase squid, fish, and other prey. But at least one ancestral species in this group of toothed whales, also known as ziphiids, was cruising near-surface waters for its meals, new evidence from newly described fossils suggest. Those remains—the first of any toothed whale to also include fossils of its presumed prey, researchers say—were unearthed along the southwestern coast of Peru last year. The rocks that entombed the partial remains of the whale (Messapicetus gregarius, depicted in an artist’s reconstruction, above) accumulated as sea-floor sediments between 8.9 million and 9.9 million years ago, other fossils in the rocks suggest. The whale’s remains would be largely unremarkable if not for the large number of sardinelike fish preserved inside its chest cavity and around its head. Because scales of the fish show few signs of being exposed to stomach acid, the fish must have been consumed shortly before the whale died and sank to the sea floor, the researchers report online today in the Proceedings of the Royal Society B. Scales of such fish are rarely preserved in the rocks of that area, so those fish (which likely fed at or near the ocean’s surface, as their modern kin do) probably are the remains of the whale’s last meal and were expelled from the carcass as decomposition bloated the whale’s gut, the researchers propose. The size of the whale’s last meal—somewher between 40 and 60 fish averaging 39 centimeters in length and together weighing between 16 and 25 kilograms—generally matches a stomach full of fish consumed by similar-sized modern-day relatives. The new find helps shed light on the evolution of beaked whales as well as their competition: Soon after M. gregarius swam the region’s seas, dolphins appeared on the scene, and their success in shallow coastal waters (wher they now dominate), may have driven ziphiids to abandon foraging in surface waters.