Masillastega, Mayr, 2002

Mayr, Gerald, 2002, A skull of a new pelecaniform bird from the Middle Eocene of Messel, Germany, Acta Palaeontologica Polonica 47 (3), pp. 507-512 : 508

Masillastega gen. nov.

Type species: Masillastega rectirostris sp. nov.

Etymology: The genus name is derived from Masilla (Latin), an old Latin name for Messel and steganos (Greek), webbed, in reference to the pelecaniform affinities of the new taxon (all extant pelecaniform birds have webbed feet). The name is feminine in gender.

Diagnosis.—The genus Masillastega is characterized by the following features: beak straight and conical, deep in its proximal part and measuring more than 2/3 of entire length of skull; tip of the rostrum slightly hooked; narial openings greatly ossified; dorsal surface of mandibular rami medio−laterally very wide; tip of mandible truncated in lateral view and pars symphysialis short; upper beak and mandible bearing many impressions of vessels; recessus tympanicus dorsalis deep.

Differential diagnosis.— Masillastega n. gen. differs from:

– all extant Pelecaniformes in the shape of the long and dorso−ventrally high beak (see description below);

– the Eocene pelecaniform genera Limnofregata Olson, 1977 ( Fregatidae ) and Prophaethon Andrews, 1899 ( Prophaethontidae ) in the strongly ossified narial openings (long and slit−like in the former two genera) and the relatively longer beak which lacks a hooked rostrum in Prophaethon ;

– Eostega lebedinskyi Lambrecht, 1929 in its smaller size ( Lambrecht 1929 estimated the total length of the mandible of Eostega at about 152mm, in the Messel pele − caniform it measures 135 mm) and in the straight dorsal margin of the mandibular rami (slightly convex in Eostega , see Lambrecht 1929: fig. 13).

Remarks.—The description of two large avian taxa from Messel, i.e. the idiornithid species Idiornis tuberculata Peters, 1985 and the putative phorusrhacid Aenigmavis sapea Peters, 1987 , is based on postcranial material only. However, a possibly idiornithid skull from Messel was identified by Peters (1988: fig. 202), which resembles the skull of extant Cariamidae (seriemas) and bears no resemblance to that of Masillastega . Independent thereof, whether it is a true phorusrhacid or a flightless member of the Idiornithidae (see Mayr 2000b), it is also very unlikely that Aenigmavis sapea had a “pelecaniform” skull.