ABSTRACT

The first unequivocal records of teratornithid birds from the Pleistocene of South America are here described, adding a new member, and the largest, to this highly diversified guild of large carnivorous flying birds that lived during these times in the Americas. The new specimens come from four fossiliferous localities of Central Argentina that range in age from the late middle to the early late Pleistocene, and agree with other known Teratornithidae taxa in size and morphology. We updated the taxonomy of the family and analyzed its fossil record in the Pleistocene of both Americas. The available evidence suggests that forms related to Teratornis lived in the South American Pampas around the time of the Last Interglacial (MIS 5), but they were restricted to North America during the latest Pleistocene (late MIS 3–early MIS 1). The contrasting latest Pleistocene record of teratorns between North and South America is not easy to understand, especially because the supposed flight capacity of these birds did not prevent them from crossing large geographical barriers. Although a bias in the fossil record cannot be ruled out, it is possible that the teratorns were limited in South America by paleoclimatic–paleoecological factors as yet undetermined, and/or that the northern and southern Pleistocene species had very dissimilar specializations. In relation to the latter, the previous inferences on the teratorn paleobiology without phylogenetic support are preliminarily questioned here.

摘要

这里描述了来自南美洲更新世的 tereratornithid 鸟类的第一个明确记录，为这个时期生活在美洲的大型食肉飞鸟的高度多样化的行会增加了一个新成员，也是最大的成员。新标本来自阿根廷中部的四个化石产地，年龄从中晚期到更新世晚期，在大小和形态上与其他已知的 Tereratornithidae 分类群一致。我们更新了该科的分类并分析了其在美洲更新世的化石记录。现有证据表明，与Teratornis相关的形式在末次间冰期 (MIS 5) 前后，它们生活在南美潘帕斯草原，但在最新更新世 (MIS 3 晚期 - MIS 1 早期) 期间，它们仅限于北美。北美和南美之间更新世最新记录的对比并不容易理解，特别是因为这些鸟类的假定飞行能力并没有阻止它们跨越巨大的地理障碍。尽管不能排除化石记录中的偏差，但南美洲的畸胎者可能受到尚未确定的古气候-古生态因素的限制，和/或北部和南部更新世物种具有非常不同的特化。关于后者，在此初步质疑先前在没有系统发育支持的情况下对畸胎古生物学的推论。