Pterodroma Bonaparte, 1856

Genus Pterodroma Bonaparte, 1856 View in CoL

The material presented herein is included in the genus Pterodroma because of the following combination of characters: the dorsal distal outline of the premaxilla shows a deep concave kink in lateral view, the lachrymal is perfectly fused to the frontal and ectethmoid without any noticeable remaining suture between them forming part of the anterior wall of the eye socket ( Warham 1996).

The bones are larger than Hydrobatidae and Oceanitidae with different proportions to those of Oceanitidae as they have short, stout humeri, ulnae, and femora, and greatly elongated tibiotarsi and tarsometatarsi (Olson 1985). These bones show no tendency toward the deep-diving adaptations of Puffinus or Pelecanoides in either the wing (flattened humerus and ulna) or hindlimbs (enlargement of crista cnemialis of the tibiotarsi and flattened tarsometatarsi) ( Warham 1996). The cranium lacks the elongation of the area between the ectethmoid and the nasofrontal hinge with anterior elongation of the lacrimal typical of Oceanitidae (Olson and James 1991) .

The fusion of the lachrymal to the frontal and ectethmoid is absent in most Procellariformes (Olson 1975b, Wharham 1996), but is present in the close genus Lugensa . The present material can be differentiated from Lugensa by the presence of a fenestrated fossa glandulae nasalis in the latter ( Maurício 2014).

The shape of the fossil humeri also differs from the very slender and cylindrical humeri of Bulweria ( Kuroda, 1983) . In addition, the shape of these bones and the limb proportions are like other Pterodroma species ( Pt. madeira , Pt. feae , Pt. cahow , and Pt. deserta ) and different from those of Bulweria (Olson, 1975b) .

These anatomical features have been checked with skeletons of Pt. madeira , Pt. feae , Pt. cahow , and Pt. deserta , Puffinus puffinus (Brünnich, 1764) , Pu. baroli Bonaparte, 1856 , and Bulweria bulwerii (Jardine and Selby, 1828) ( Procellariidae ), Pelagodroma marina (Latham, 1790) ( Oceanitidae ), and Hydrobates pelagicus (Linnaeus, 1758) ( Hydrobatidae ).