Muriwaimanu Mayr et al., 2018

Mayr, Gerald, De Pietri, Vanesa L., Proffitt, James, Blokland, Jacob C., Clarke, Julia A., Love, Leigh, Mannering, Al A., Crouch, Erica M., Reid, Catherine & Scofield, R. Paul, 2025, Multiple exceptionally preserved fossils from the Paleocene Waipara Greensand inform the diversity of the oldest stem group Sphenisciformes and the formation of their diving adaptations, Zoological Journal of the Linnean Society 204 (4) : -

Muriwaimanu Mayr et al., 2018

Emended diagnosis: Stem group sphenisciforms the size of the extant Megadyptes antipodes , which are characterized by a scapula that widens towards the caudal end of the bone, with the greatest width of the scapular blade being about twice its minimum width; a coracoid that is shorter than the femur; a dorsomedially (rather than medially) directed processus procoracoideus; an extremitas sternalis of the furcula that lacks an apophysis furculae; a crista bicipitalis of the humerus that forms a marked distal convexity; a long and narrow tuberculum dorsale of the humerus, which reaches distally to the level of the distal terminus of the crus dorsale fossae; a plantar articular surface of trochlea metatarsi III that is not proximally tapering.