Odontopteryx - Species and Taxonomy

Species and Taxonomy

One species of Odontopteryx has been formally described, but several other named taxa of pseudotooth birds might belong here too. The type species Odontopteryx toliapica is known from the Ypresian (Early Eocene) London Clay of the Isle of Sheppey (England) and slightly older rocks of the Ouled Abdoun Basin (Morocco). Its tarsometatarsus (e.g. specimen BMNH A4962) was for some time in the late 20th century believed to be from a giant procellariiform and called Neptuniavis minor, but specimen BMNH A44096 – the holotype skull described by Richard Owen in 1873 – was the first pelagornithid recognized as such, and not assigned to some other seabird lineage. It was still often allied with Sulidae (boobies and gannets) or Diomedeidae (albatrosses), to which it is quite certainly not closely related.

One to five (or perhaps more) additional unnamed species are tentatively assigned to the present genus, mainly due to their size and/or forward-angled "teeth": one smaller and one larger than O. toliapica and also from the Late Paleocene or Early Eocene of the Ouled Abdoun Basin in Morocco, one from the mid-Eocene of Uzbekistan, one from Middle Eocene strata of the Tepetate Formation from near El Cien (Baja California Sur, Mexico), and one from the Early Eocene of Virginia, USA. As regards the Moroccan fossils, however, the largest of the three Odontopteryx-like forms (initially called "Odontopteryx n. sp. 2") has provisionally been termed "Odontopteryx gigas" but may in fact be a Dasornis, while the smallest ("Odontopteryx n. sp. 1") has been considered a distinct genus (as "Odontoptila inexpectata") but that name is both a nomen nudum and would in any case be a junior homonym of the geometer moth genus Odontoptila and thus unavailable for the bird. Though the Mexican specimen (MHN-UABCS Te5/6–517, a distal humerus piece) agrees with O. toliapica in size and shape, it is not entirely clear whether the American forms belong in this otherwise Eurasian genus. It must be remembered, however, that at that their time the Isthmus of Panama had not been formed yet.

Pseudodontornis tschulensis from the Late Paleocene of Zhylga (Kazakhstan) is sometimes placed in Odontopteryx, as is Macrodontopteryx oweni which was also found in the London Clay. In the latter case however, this does not seem to be correct (see below). The species originally described as O. longirostris was made the type species of Pseudodontornis in 1930. Small pelagornithid specimens have also been reported from the Early Oligocene Kishima Group and the Late Oligocene Ashiya Group of Japan, but their placement in Odontopteryx is even more uncertain.

"Neptuniavis" minor was described from remains assigned to O. toliapica by Richard Lydekker in 1891. However, the supposed procellariiform genus Neptunavis is actually a pseudotooth bird too, and hence the smaller "species" is here synonymized as proposed by Lydekker. The type species "N." miranda, on the other hand, is a junior synonym of the large Dasornis emuinus. In a peculiar twist, some material assigned to "N." minor eventually turned out to be remains of the paleognath Lithornis vulturinus; the very first described bone of Dasornis emuinus on the other hand – a humerus piece – was at first mistaken for to be a Lithornis tarsometatarsus.