Phylogenetic characters in the humerus and tarsometatarsus of penguins

The present review aims to improve the scope and coverage of the phylogenetic matrices currently in use, as well as explore some aspects of the relationships among Paleogene penguins, using two key skeletal elements, the humerus and tarsometatarsus. These bones are extremely important for phylogenetic analyses based on fossils because they are commonly found solid specimens, often selected as holo- and paratypes of fossil taxa. The resulting dataset includes 25 new characters, making a total of 75 characters, along with eight previously uncoded taxa for a total of 48. The incorporation and analysis of this corrected subset of morphological characters raise some interesting questions considering the relationships among Paleogene penguins, particularly regarding the possible existence of two separate clades including Palaeeudyptes and Paraptenodytes, the monophyly of Platydyptes and Paraptenodytes, and the position of Anthropornis. Additionally, Notodyptes wimani is here recovered in the same collapsed node as Archaeospheniscus and not within Delphinornis, as in former analyses.