Macrodontopteryx

Macrodontopteryx is a genus of the prehistoric pseudotooth birds of somewhat doubtful validity. These animals were probably rather close relatives of either pelicans and storks, or of waterfowl, and are here placed in the order Odontopterygiformes to account for this uncertainty.[1]

Macrodontopteryx
Temporal range: Early Eocene
51–50 Ma
↓
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: †Odontopterygiformes
Family: †Pelagornithidae
Genus: †Macrodontopteryx
Harrison & C.A.Walker, 1976
Species:
†M. oweni
Binomial name
†Macrodontopteryx oweni
Synonyms

see text

Description

Only a single species, Macrodontopteryx oweni, is known to date. Its remains were found in the Ypresian (Early Eocene) London Clay of the Isle of Sheppey (England), where they were deposited about 50 Ma (million years ago) in the Mammal Paleogene zone MP8-9. The fossils were at first assigned to Argillornis longipennis, which is nowadays recognized as junior synonym of Dasornis emuinus, a larger pseudotooth bird than M. oweni. Due to the scarcity of their fossil remains, is not clear whether the pseudotooth bird species described as Pseudodontornis longidentata is not the same as M. oweni, though its size suggests that it is more likely to be synonymous with D. emuinus. In any case, Macrodontopteryx itself may well be no distinct genus but rather a large member of the contemporary and sympatric Odontopteryx, or a young or small Dasornis.[2]

The only known specimen (BMNH A1) is an incomplete and rather crushed skull with much all of the beak missing. In the living animal it would have measured roughly 30–35 cm (one foot). The wingspan was probably around 4 m (13 ft).[3]

Other supposed remains

If Macrodontopteryx is indeed a distinct genus, perhaps some pseudotooth bird fossils found in Lutetian (Middle Eocene, MP11-13, about 45 Ma) deposits at Etterbeek (Belgium) belong therein. Like the holotype BMNH A1, they have been assigned to Argillornis longipennis in the past; at least some of the material[4] placed in that taxon at one time or another – but not its syntype humerus pieces – seems too small to be of an adult Dasornis.[5]

An Early Oligocene (Stampian, MP21-23, about 32 Ma) distal radius from Hamstead, Isle of Wight (England) was also assigned to Macrodontopteryx. It is without doubt from a very large and flight-capable bird, but little else can be said about it. An equally old cervical vertebra fragment (specimen BMNH A-4413) and a toe phalanx from nearby Yarmouth were, mainly due to their size, believed to be related to the enigmatic large flightless bird (and presumed ratite) Eleutherornis. They were described as Proceriavis martini,[6] but have never been compared in detail to pseudotooth bird fossils. It cannot be ruled out that Proceriavis belongs in the Pelagornithidae, but whether it would be a junior synonym of Macrodontopteryx is highly uncertain given the 20-million-year difference between the Isle of Sheppey and Isle of Wight material. [7] Recent analysis suggests that the material referred to as Proceriavis is in fact ratite in nature.[8]

Footnotes
  1. Bourdon (2005), Mayr (2009: p.59)
  2. Mlíkovský (2002: p.82), Bourdon (2005), Mayr (2008, 2009: p.56)
  3. Mlíkovský (2002: p.82), Mayr (2008, 2009: pp.56-57)
  4. E.g. the humerus fragments BMNH A5 and BMNH A8 or the proximal left ulna piece BMNH A94: Goedert (1989)
  5. Brodkorb (1963: pp.248-249), Goedert (1989), Mlíkovský (2002: p.83, 2009), Mayr (2008, 2009: p.56)
  6. "E. helveticus" in Mayr (2009: p.31) is a lapsus
  7. Mlíkovský (1996, 2002: p.269), Mayr (2009: p.31)
  8. Agnolin et al, Unexpected diversity of ratites (Aves, Palaeognathae) in the early Cenozoic of South America: palaeobiogeographical implications Article in Alcheringa An Australasian Journal of Palaeontology · July 2016 DOI: 10.1080/03115518.2016.1184898

References
  • Bourdon, Estelle (2005): Osteological evidence for sister group relationship between pseudo-toothed birds (Aves: Odontopterygiformes) and waterfowls (Anseriformes). Naturwissenschaften 92(12): 586–591. doi:10.1007/s00114-005-0047-0 (HTML abstract) Electronic supplement (requires subscription)
  • Goedert, James L. (1989): Giant Late Eocene Marine Birds (Pelecaniformes: Pelagornithidae) from Northwestern Oregon. J. Paleontol. 63(6): 939–944. Abstract and first page text
  • Mayr, Gerald (2008): A skull of the giant bony-toothed bird Dasornis (Aves: Pelagornithidae) from the Lower Eocene of the Isle of Sheppey. Palaeontology 51(5): 1107–1116. doi:10.1111/j.1475-4983.2008.00798.x (HTML abstract)
  • Mayr, Gerald (2009): Paleogene Fossil Birds. Springer-Verlag, Heidelberg & New York. ISBN 3-540-89627-9
  • Mlíkovský, Jirí (1996): Tertiary avian localities of the United Kingdom. Acta Universitatis Carolinae: Geologica 39: 759–771. PDF fulltext
  • Mlíkovský, Jirí (2002): Cenozoic Birds of the World, Part 1: Europe. Ninox Press, Prague. ISBN 80-901105-3-8 PDF fulltext
  • Mlíkovský, Jirí (2009): Evolution of the Cenozoic marine avifaunas of Europe. Annalen des Naturhistorischen Museums Wien A 111: 357–374 PDF fulltext
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