Worthy Trevor H, Degrange Federico J, Handley Warren D, Lee Michael S Y
College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia.
Centro de Investigaciones en Ciencias de la Tierra (CICTERRA), UNC, CONICET, Av. Vélez Sársfield 1611, X5016GCA, Córdoba, Argentina.
R Soc Open Sci. 2017 Oct 11;4(10):170975. doi: 10.1098/rsos.170975. eCollection 2017 Oct.
The extinct dromornithids, gastornithids and phorusrhacids are among the most spectacular birds to have ever lived, with some giants exceeding 500 kg. The affinities and evolution of these and other related extinct birds remain contentious, with previous phylogenetic analyses being affected by widespread convergence and limited taxon sampling. We address these problems using both parsimony and tip-dated Bayesian approaches on an expansive taxon set that includes all key extinct flightless and flighted (e.g. and lithornithids) forms, an extensive array of extant fowl (Galloanseres), representative Neoaves and palaeognaths. The Paleogene volant Lithornithidae are recovered as stem palaeognaths in the Bayesian analyses. The Galloanseres comprise four clades inferred to have diverged in the Late Cretaceous on Gondwana. In addition to Anseriformes and Galliformes, we recognize a robust new clade (Gastornithiformes) for the giant flightless Dromornithidae (Australia) and Gastornithidae (Eurasia, North America). This clade exhibits parallels to ratite palaeognaths in that flight presumably was lost and giant size attained multiple times. A fourth clade is represented by the Cretaceous (Antarctica), which was strongly excluded from Anseriformes; thus, a crucial molecular calibration point needs to be reconsidered. The presbyornithids (Australia) and (Northern Hemisphere) are robustly found to be the sister group to Anatoidea (Anseranatidae + Anatidae), a relatively more basal position than hitherto recognized. South America's largest bird, , is not a galloansere, but a member of Neoaves related to Cariamiformes; therefore, giant Galloanseres remain unknown from this continent. Trait analyses showed that while gigantism and flightlessness evolved repeatedly in groups, diet is constrained by phylogeny: all giant Galloanseres and palaeognaths are herbivores or mainly herbivorous, and giant neoavians are zoophagous or omnivorous.
已灭绝的恐鸟目、加斯通鸟科和窃鹤科鸟类是有史以来最引人注目的鸟类之一，有些巨型鸟类体重超过500千克。这些以及其他相关已灭绝鸟类的亲缘关系和进化仍然存在争议，先前的系统发育分析受到广泛趋同和分类群抽样有限的影响。我们在一个广泛的分类群集合上使用简约法和末端定年贝叶斯方法来解决这些问题，该集合包括所有关键的已灭绝不会飞和会飞的（如始祖鸟科和石鸟科）类群、大量现存的家禽（鸡雁小纲）、有代表性的新鸟亚纲和古颚类。在贝叶斯分析中，古近纪会飞的石鸟科被恢复为古颚类的基部类群。鸡雁小纲包括四个推断在晚白垩世冈瓦纳大陆上分化的分支。除了雁形目和鸡形目，我们为巨型不会飞的恐鸟目（澳大利亚）和加斯通鸟科（欧亚大陆、北美洲）识别出一个强有力的新分支（加斯通鸟形目）。这个分支与平胸古颚类有相似之处，即飞行可能多次丧失且体型达到巨大。第四个分支由白垩纪的南极鸟（南极洲）代表，它被强烈排除在雁形目之外；因此，一个关键的分子校准点需要重新考虑。已确定鸭雁类（澳大利亚）和（北半球）是鸭形总目（叫鸭科 + 鸭科）的姐妹群，这一位置比迄今所认识的相对更基部。南美洲最大的鸟类，不是鸡雁小纲成员，而是与叫鹤目相关的新鸟亚纲成员；因此，该大陆不存在巨型鸡雁小纲鸟类。性状分析表明，虽然体型巨大和不会飞行在不同类群中多次进化，但食性受系统发育限制：所有巨型鸡雁小纲鸟类和古颚类都是草食动物或主要为草食性，而巨型新鸟亚纲是肉食性或杂食性。
