Four genera of distantly phylogenetically very large volant birds existed for most of the Pliocene: Pelagornithidae seabirds; the large North American…

Four genera of distantly phylogenetically very large volant birds existed for most of the Pliocene: Pelagornithidae seabirds; the large North American…

While pelagornithid or ‘bony-toothed’ bird fossils representing multiple species are known from Antarctica, a new dentary fragment of a pelagornithid bird from the middle Eocene Submeseta Formation on Seymour Island, Antarctica represents a species with a body size on par with the largest known species in the clade. Measurements from the partial ‘toothed’ dentary point to a giant body size for the species, although the spacing among the pseudoteeth differs from that published for other pelagornithids. The discrepancy might suggest that previous techniques are not adequate for examination of incomplete material or that another factor such as phylogeny might impact size estimates and comparisons. Combined with a revised stratigraphic position in the early Eocene La Meseta Formation on Seymour Island for the largest pelagornithid tarsometatarsus known, these Antarctic fossils demonstrate the early evolution of giant body size in the clade (by ~ 50 Ma), and they likely represent not only the largest flying birds of the Eocene but also some of the largest volant birds that ever lived (with an estimated 5–6 m wingspan). Furthermore, the distribution of giant-sized pelagornithid fossils across more than 10 million years of Antarctic geological deposits points to a prolonged survival of giant-sized pelagornithids within the southern seas, and their success as a pelagic predatory component of marine and coastal ecosystems alongside early penguins.

Four genera of distantly phylogenetically very large volant birds existed for most of the Pliocene: Pelagornithidae seabirds; the large North American…

本期“科学快讯”（Science, Quickly）节目聚焦于一种被遗忘的史前巨鸟Pelagornis sandersi，该物种化石在被发掘后沉寂三十余年才被重新认识。由古鸟类古生物学家Daniel Ksepka主导的研究揭示了这种生活在约2700万年前的巨鸟，其翼展可达20英尺，体重相当于一辆跑车，是当时顶级掠食者。 Pelagornis sandersi的独特之处在于其骨质的“假牙”，这些并非真牙的骨质突起，能有效帮助其捕食滑溜的鱼类和鱿鱼。此外，其肩部骨骼结构异常，可能限制了其翅膀的活动范围，表明它并非主动扇动翅膀，而是更依赖滑翔来飞行，如同一个巨大的风筝。 该巨鸟的化石最初于20世纪80年代在美国南卡罗来纳州查尔斯顿机场附近被发现，后被当地博物馆的古生物学家Al Sanders收藏，直至Ksepka在三十年后才对其进行科学描述并命名。这一发现的重要性在于，它证明了在恐龙灭绝后，鸟类迅速填补了大型飞行生物的生态位，Pelagornithidae（假齿鸟科）便是其中的代表。 Ksepka指出，Pelagornithidae的广泛分布（遍及全球各大洲）表明它们在后恐龙时代抓住了演化机遇。这次对Pelagornis sandersi的深入解读，也为理解地球生命演化史上，灭绝事件如何为新物种的崛起和多样化提供空间提供了重要例证。 查看消息来源

Scientific Reports - Earliest fossils of giant-sized bony-toothed birds (Aves: Pelagornithidae) from the Eocene of Seymour Island, Antarctica