Pseudotoothed Birds (Aves, Odontopterygiformes) from the Early Tertiary of Morocco

Abstract

We describe here new specimens of pseudotoothed birds (Odontopterygiformes) from the Upper Paleocene and Lower Eocene of the Ouled Abdoun Basin, Morocco. These Lower Paleogene fossils are among the oldest representatives of the Odontopterygiformes and include braincases, beak fragments, and long bones. Dasornis toliapica (Owen, 1873) (2-3 m wingspan) and Dasornis emuinus (Bowerbank, 1854) (3.5-4.5 m wingspan) were initially described from the Lower Eocene London Clay of Sheppey, England. The new species Dasornis abdoun (1.5-1.7 m wingspan) constitutes the smallest species of pseudotoothed bird ever discovered. We partly revise the oversplit taxonomy of the odontopterygiforms: the two species from the Paleogene of England and Morocco are regarded as congeneric, the name Dasornis having priority over the name Odontopteryx. We also synonymize Neptuniavis minor Harrison and Walker, 1977, and Macrodontopteryx oweni Harrison and Walker, 1976, with D. toliapica (Owen, 1873. Moreover, the genera Pelagornis Lartet, 1857, and Osteodontornis Howard, 1957, are regarded as pertaining to one single taxonomic entity that corresponds to the Pelagornis morphotype. In Dasornis, the morphological peculiarities of the humerus that are related to gliding flight are less pronounced than in Pelagornis. The latter taxon includes exceedingly specialized gliders that were most likely unable of sustained flapping flight and relied almost entirely on winds to provide lift. Pseudotoothed birds pertaining to the Dasornis morphotype were more generalists and could probably undertake flapping flight, even if limited. The species of Dasornis were soaring pelagic feeders that could disperse over large territories like extant albatrosses. They formed large breeding colonies near the shore of the

The Pseudo‐toothed Birds (Aves, Odontopterygiformes) and their Bearing on the Early Evolution of Modern Birds

“…Very long wings and short legs may have required peculiar takeoff and landing conditions. The wingspan of the smallest representatives of these birds was slightly smaller than that of a northern gannet (around 1.6 m: Bourdon, 2006a;Bourdon et al, 2010), and the largest were truly gigantic, reaching a wingspan of 5.5-6 m (Olson, 1985), which is two times larger than that of extant albatrosses. The morphology of the proximal humerus is highly distinctive (Figure 8.…”

Primer registro de aves fósiles (Pelecaniformes: Pelecanidae y un probable Odontopterygifomres: Pelagornithidae) para el Mioceno Superior de Costa Rica

“…Los Pelagornithidae han sido hallados en todos los continentes, a excepción de Australia aunque si se han registrado en Nueva Zelanda, en sedimentos que datan del Paleoceno tardío hasta el Plioceno tardío (Olson, 1985;Bourdon et al, 2010;Mayr, 2011). En Norteamérica los registros de Pelagornithidae inician en el Eoceno tardío de Oregón (Goedert, 1989), Oligoceno tardío-Mioceno Inferior de las Formaciones Hawthorne y Ashley en South Carolina, Mioceno Medio de la Formación Calvert en Maryland y Virginia, Plioceno Inferior de Lee Creek Mine en North Carolina, todos en la costa este de Estados Unidos (Olson, 1985).…”

Review of the putative Phorusrhacidae from the Cretaceous and Paleogene of Antarctica: new records of ratites and pelagornithid birds

“…Initially this character was also mentioned as a synapomorphy of "Pelecani− formes" + Procellariiformes by Cracraft (1988:349, character 3) but currently is considered as an apomorphy of a more comprehensive group, the "Waterbird as− semblage" (Aequornithes sensu Mayr 2010, see also Mayr and Clarke 2003;Mayr 2003;Ericson et al 2006;Hackett et al 2008;Hieronymus and Witmer 2010; in− cluding Procellariiformes, "Pelecaniformes", "Ciconiiformes", Sphenisciformes, Scopidae, Balaenicipitidae, and Threskiornithidae). Other non−related group that exhibits the abovementioned groove is Pelagornithidae (e.g., Bourdon et al 2010;Mayr and Rubilar−Rogers 2010). Even though the presence of these last two groups of birds have been referred to the same stratigraphic unit bearing UCR 22175 (for a summary of these records see Tambussi and Acosta Hospitaleche 2007), such material coincides only with the morphology seen in Ratitae.…”

“…1957, 1978Howard and White 1962;Hopson 1964;Olson 1984Olson , 1985Goedert 1989;Olson and Rasmussen 2001;Stidham 2004;Chavez et al 2007;Mayr et al 2008;Mourer−Chauviré and Geraads 2008). Within the pelagornithids, in which the distal end of the tarsometatarsus is known, UCR 22176 resembles those included within the Dasornis morphotype, and differs from the Pelagornis/Osteodontornis morphotype in the following combination of features ( Mayr et al 2008;Mayr 2009;Bourdon et al 2010;Mayr and Smith 2010). It is remarkable that within the pelagornithids, the Seymour Island material has close affinity with the specimen referred by Hopson (1964) to Palaeochenoides miocaenus Shufeldt, 1916 reported for deposits of South Carolina in the North At− lantic coast, and tentatively referred to the Early Miocene by this author (although it probably belong to Late Oligocene according to Olson 1985; see also Mayr and Rubilar−Rogers 2010).…”

“…Fur− thermore, the size could be proportionally larger if it is considered that the paleogene forms of Dasornis morphotype show a lateromedially much narrower tarsometatarsus than the very wide and dorsoplantarly compressed tarsometa− tarsus of the neogene Pelagornis/Osteodontornis (Mayr and Rubilar−Rogers 2010;Bourdon et al 2010).…”