ABSTRACT

Here, we report on two tarsometatarsi assignable to relatively small-sized Eocene Antarctic penguins, housed in the palaeozoological collections of Naturhistoriska riksmuseet, Stockholm. The Priabonian fossils were collected by museum staff during two joined Argentinean and Swedish expeditions from the Submeseta Formation on Seymour Island, Antarctic Peninsula. One specimen represents a new early sphenisciform, Marambiornopsis sobrali gen. et sp. nov., the sixth small-sized tarsometatarsus-based penguin species known from the Antarctic Eocene. Micro-CT scanning revealed the presence of quite large and essentially empty metatarsal medullary cavities. The second fossil can unequivocally be assigned to Mesetaornis polaris. The specimen represents only the second record of this species and supposedly a relatively young bird. Micro-CT scanning showed that in M. polaris the metatarsal medullary cavities are less developed than in M. sobrali – the cortical and trabecular bone tissues left rather little room for significant hollow spaces. Both specimens also differ in overall density of their trabecular networks.Genus name: LSIDurn:lsid:zoobank.org:act:604F02AA-DD0C-4789-B4D6-85EA68A39A68

Species name: LSIDurn:lsid:zoobank.org:act:477F0FC5-D07B-4A92-97FD-3C4805BAF503

摘要

在这里，我们报告了两只可归属于相对较小的始新世南极企鹅的 tarsotatarsi，它们被安置在斯德哥尔摩 Naturhistoriska riksmuseet 的古动物收藏中。Priabonian 化石是由博物馆工作人员在阿根廷和瑞典的两次联合探险队中从南极半岛西摩岛的 Submeseta 地层收集的。一个标本代表了一种新的早期sphenisciform，Marambiornopsis sobrali基因。等 sp. 11 月，南极始新世已知的第六种小型跗跖企鹅。Micro-CT 扫描显示存在相当大且基本上空的跖骨髓腔。第二个化石可以明确地归属于Mesetaornis polaris. 该标本仅代表该物种的第二个记录，据说是一只相对年轻的鸟。显微 CT 扫描显示，在M. polaris 中，跖骨髓腔不如M. sobrali 中发达——皮质和骨小梁组织为显着的中空空间留下了相当小的空间。两个标本的小梁网络的整体密度也不同。属名：LSIDurn:lsid:zoobank.org:act:604F02AA-DD0C-4789-B4D6-85EA68A39A68

物种名称：LSIDurn:lsid:zoobank.org:act:477F0FC5-D07B-4A92-97FD-3C4805BAF503