Pelagornithidae

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Pelagornithidae
Temporal range:
Ma
NMNH
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Clade: incertae sedis
Order: †Odontopterygiformes
Howard, 1957
Family: †Pelagornithidae
Fürbringer, 1888
Genera

See text

Synonyms
Family synonymy but see text
  • Cyphornithidae Wetmore, 1928
  • Dasornithidae Harrison & Walker, 1976
  • Gyphornithidae (lapsus)
  • Odontopterygidae Lydekker, 1891
  • Pseudodontornithidae Lambrecht, 1933

The Pelagornithidae, commonly called pelagornithids, pseudodontorns, bony-toothed birds, false-toothed birds or pseudotooth birds, are a

Early Paleocene and the Pliocene-Pleistocene boundary.[1][2]

Most of the common names refer to these

teeth, contained Volkmann's canals and were outgrowths of the premaxillary and mandibular bones. Even "small" species of pseudotooth birds were the size of albatrosses; the largest ones had wingspans estimated at 5–6 metres (15–20 ft) and were among the largest flying birds ever to live. They were the dominant seabirds of most oceans throughout most of the Cenozoic, and modern humans apparently missed encountering them only by a tiny measure of evolutionary time: the last known pelagornithids were contemporaries of Homo habilis and the beginning of the history of technology.[3]

Description and ecology

Skull of Pelagornis mauretanicus

The biggest of the pseudotooth birds were the largest flying birds known. Almost all[4] of their remains from the Neogene are immense, but in the Paleogene there were a number of pelagornithids that were around the size of a great albatross (genus Diomedea) or even a bit smaller. The undescribed species provisionally called "Odontoptila inexpectata"[5] – from the Paleocene-Eocene boundary of Morocco – is the smallest pseudotooth bird discovered to date and was just a bit larger than a white-chinned petrel (Procellaria aequinoctialis).[6]

The Pelagornithidae had extremely thin-walled bones widely

glenoid joint unmatched by any other known bird. This is especially prominent in the Neogene pelagornithids, and less developed in the older Paleogene forms. The sternum had the deep and short shape typical of dynamic soarers, and bony outgrowths at the keel's forward margin securely anchored the furcula.[7]

Skull of Odontopteryx toliapica (white areas are restored). Unlike in other pseudotooth birds, the "teeth" in this genus were slanted forwards.

The legs were proportionally short, the feet probably webbed and the

eye sockets of at least some pseudotooth birds – perhaps only in the younger species – were well-developed salt glands.[8]

Altogether, almost no major body part of pelagornithids is known from a well-preserved associated fossil and most well-preserved material consists of single bones only; on the other hand the long occurrence and large size makes for a few rather comprehensive (though much crushed and distorted) remains of individual birds that were entombed by as they lay dead, complete with some fossilized

cranium known as of 2009.[9]

Ecology and extinction

Pteranodon skeleton. A toothless Late Cretaceous pterosaur, it was similar to Pelagornis in size and proportions and possibly in feeding habits.

Unlike the

plotopterids – both wing-propelled divers that foraged over the continental shelf – are almost invariably found in the company of pseudotooth birds. Thus, pseudotooth birds seem to have gathered in some numbers in upwelling regions, presumably to feed but perhaps also to breed nearby.[12]

Pelagornis chilensis skeleton seen from below

It is sometimes claimed that as with some other

population densities.[14]

Thus, direct competition for food between bony-toothed birds and cetaceans or pinnipeds cannot have been very severe. As both the birds and pinnipeds would need level ground near the sea to raise their young, competition for breeding grounds may have affected the birds' population. In that respect, the specializations for dynamic soaring restricted the number of possible nesting sites for the birds, but on the other hand upland on islands or in coastal ranges could have provided breeding grounds for Pelagornithidae that was inaccessible for pinnipeds; just as many

Necker Island for example was of significant size 10 million years ago, when Osteodontornis roamed the Pacific.[15]

Squalodon calvertensis, a shark-toothed whale from the Middle Miocene

There is no obvious single reason for the pseudotooth birds' extinction. A scenario of general ecological change – exacerbated by the

seagulls were very rarely found in association with the Pelagornithidae.[16]

Irrespective of the cause of their ultimate extinction, during the long time of their existence the pseudotooth birds furnished

mako sharks, Carcharodon white sharks,[17] the snaggletooth shark Hemipristis serra, tiger sharks (Galeocerdo), Carcharhinus whaler sharks, the lemon shark (Negaprion brevirostris) and hammerhead sharks (Sphyrna), and perhaps (depending on the bird fossils' age) also Pristis sawfishes, Odontaspis sand tiger sharks, and Lamna and Parotodus benedeni mackerel sharks. It is notable that fossils of smaller diving birds – for example auks, loons and cormorants – as well as those of albatrosses are much more commonly found in those shark pellets than pseudotooth birds, supporting the assumption that the latter had quite low population densities and caught much of their food in mid-flight.[18]

A study on Pelagornis' flight performance suggests that, unlike modern seabirds, it relied on thermal soaring much like continental soaring birds and Pteranodon.[19]

External appearance

A generic reconstruction of Osteodontornis

Nothing is known for sure about the colouration of these birds, as they left no living descendants. But some

freshwater habitat.[20]

If the pseudotooth birds are

Bali starling (Leucopsar rothschildi). This is due to the fact that melanins will polymerize, making all-black feathers very robust; as the largest forces encountered by bird feathers affect the flight feathers, the large amount of melanin gives them better resistance against being damaged in flight. In soaring birds as dependent on strong winds as the bony-toothed birds were, black wingtips and perhaps tails[21] can be expected to have been present.[20]

As regards the bare parts, all the presumed close relatives of the Pelagornithidae quite often have rather bright reddish colours, in particular on the

mating displays. Sexual dimorphism was probably almost nonexistent, as it typically is among the basal Anseriformes and the "higher waterbirds".[20]

Taxonomy, systematics and evolution

The name "pseudodontorns" refers to the genus Pseudodontornis, which for some time served as the family's namesake. However, the presently used name Pelagornithidae pre-dates Pseudodontornithidae, and thus modern authors generally prefer "pelagornithids" over "pseudodontorns". The latter name is generally found in mid-20th-century literature however.[22]

Historically, the disparate bones of the pseudotooth birds were spread across six groups: a number of genera described from leg bones was placed in a family

tube-nosed seabirds (Procellariiformes).[23]

The most extensive

Elopterygidae" – yet another invalid "family", and its type genus is generally not considered a modern-type bird by current authors. Some additional tarsometatarsus (ankle) bone fragments were placed in the genus Neptuniavis and assigned to the Procellariidae in the Procellariiformes. All these remains were only shown to belong in the pseudotooth bird genus Dasornis in 2008.[24]

The most basal known pelagornithid is Protodontopteryx.[25]

Systematics and phylogeny

The

radiation, possibly a clade, of "higher waterbirds". However, the Pelagornithidae are not generally held to be a missing link between pelicans and albatrosses anymore, but if anything much closer to the former and only convergent to the latter in ecomorphology.[26]

Galloanserae, the palatine bone
("Pa") is not expanded downwards.
supraorbital salt gland
impressions of the Charadriiformes.

In 2005, a

condyles on the mandibular process of the quadrate bone, with the middle condyle beakwards of the side condyle. Their basipterygoid articulation is similar to that of the Galloanseres. At the side of the parasphenoid lamina, there is a wide platform as in Anseriformes. The bony-toothed birds' attachment of the coronoideal part of the external mandible adductor muscles was located at the midline, the rostropterygoid process had a support at its base and the mesethmoid bone had a deep depression for the caudal concha, just as in waterfowl.[27]

As regards other parts of the

plantar surface and a middle toe trochlea that is elongated, slightly oblique, projects to the underside of the foot and is pointed at the tip.[28]

It is unclear what to make of these

paraphyletic, its absence in pseudotooth birds does not provide much information on their relationship.[29]

While giant Galloanserae were common and diverse in the

monophyletic. In 2007, a far more comprehensive cladistic analysis of bird anatomy including some fossil forms (though not the crucial[30] Late Cretaceous taxa, which are usually known only from fragmentary remains) resolved the "higher waterbird" radiation somewhat better; still, the problem of leg and foot traits confounding the analysis was noticeable.[31]

As their relationships are still unresolved between Galloanserae and "higher waterbirds", the pseudotooth birds are here placed in the distinct order

neognath known.[33]

While the authors claim it is beyond the paper's scope, the study describing Protodontopteryx suggests that the proposed pro-galloansere traits might actually be plesiomorphic in relation to Aves. It also notes "striking" similarities between pelagornithids and Ichthyornis in terms of jaw anatomy, but still classifies them as neognaths due to the well-developed hypotarsal crests, a supratendineal bridge on the distal tibiotarsus and the caudally closed ilioischiadic foramen. The actual phylogenetic tree depicts them in a polytomy with both Galloanserae and Neoaves.[25]

It has been suggested at times that the "teeth" of pelagornithids were homologous with true teeth on an at least molecular level, being derived from the same programs responsible for the formation of teeth in other dinosaurs. This might have an importance to their actual phylogenetic position.[25][34]

A 2022 paper described

gastornithids, often regarded as galloanserans based on their pterygoid morphology, might instead constitute early-diverging crown-birds outside Galloanserae, or even be outside the avian crown group altogether.[35]

Genera and unidentified specimens

Due to the fragmented and crushed state of most pseudotooth bird remains, it is not clear whether the roughly one dozen

genera that have been named are all valid. Only the beaks are robust and distinctive enough to allow for good taxonomic delimitation, and even these are usually found as broken pieces. For example, Argilliornis and Neptuniavis were recently found to be arm and leg bones, respectively, of Dasornis, which until then was only known from skull bones. Size is generally regarded as reliable marker for generic diversity, but care just be taken to ascertain whether smallish specimens are not from young birds.[36]

Tentatively, the following genera are recognized:[37]

  • Protodontopteryx (Early Paleocene of New Zealand)
  • polyphyletic
    (type species in Palaeochenoides/Pelagornis)?
  • "Odontoptila" (Late Paleocene/Early Eocene of Ouled Abdoun Basin, Morocco) – a nomen nudum; preoccupied[38]
  • Odontopteryx (Late Paleocene/Early Eocene of Ouled Abdoun Basin, Morocco – Middle Eocene of Uzbekistan) – including "Neptuniavis" minor, may include "Pseudodontornis" longidentata, "P." tschulensis[verification needed] and Macrodontopteryx
  • Dasornis (London Clay Early Eocene of Isle of Sheppey, England) – including Argillornis, "Lithornis" emuinus and "Neptuniavis" miranda; may include "Odontopteryx gigas" (a nomen nudum), "Pseudodontornis" longidentata and Gigantornis
  • Macrodontopteryx (London Clay Early Eocene of England) – may include "Pseudodontornis" longidentata and/or belong in Odontopteryx
  • cf. Odontopteryx (Early Eocene of Virginia, US)[39]
  • Gigantornis (Ameki Middle Eocene of Ameki, Nigeria) – may belong in Dasornis
  • cf. Odontopteryx (Middle Eocene of Mexico)[40]
  • Pelagornithidae gen. et sp. indet. (Middle Eocene of Mount Discovery, Antarctica) – same as large Seymour Island specimen/Dasornis/Gigantornis?[41]
  • Pelagornithidae gen. et sp. indet. (Middle Eocene of Etterbeek, Belgium) – Dasornis/Macrodontopteryx?[42]
  • "Aequornis" (Middle Eocene of Kpogamé-Hahotoé, Togo) – a nomen nudum[43]
  • Pelagornithidae gen. et spp. indet. (La Meseta Middle/Late Eocene of Seymour Island, Antarctica) – two species? Same as Mount Discovery specimen/Dasornis/Gigantornis, Odontopteryx?[44]
  • Pelagornithidae gen. et sp. indet. (Late Eocene of France)[verification needed][45]
  • Pelagornithidae gen. et sp. indet. (Late Eocene of Kazakhstan) – may belong in Zheroia[46]
  • Pelagornithidae gen. et sp. indet. (Eocene of South Shetland Islands, South Atlantic)[verification needed][47]
  • cf. Dasornis[48] (Late Eocene/Early Oligocene of Oregon, US) – Cyphornis?[49]
  • cf. Macrodontopteryx (Early Oligocene of Hamstead, England) – may belong in Proceriavis[50]
  • Pelagornithidae gen. et sp. indet. (Early Oligocene of Japan)[51]
  • Caspiodontornis (Late Oligocene of Pirəkəşkül, Azerbaijan) – may belong in Guguschia
  • Palaeochenoides (Late Oligocene of South Carolina, US) – may include Pseudodontornis longirostris or belong in Pelagornis
  • Pelagornithidae gen. et sp. indet. (Late Oligocene of South Carolina, US)[52]
  • Pelagornithidae gen. et sp. indet. (Yamaga Late Oligocene of Kitakyushu, Japan) – Osteodontornis?[verification needed][53]
  • Tympanonesiotes (Late Oligocene or Early Miocene of Cooper River, US)
  • Cyphornis (Early Miocene of Carmanah Point, Vancouver Island, Canada) – may include Osteodontornis
  • Osteodontornis (Early Miocene – Early Pliocene) – may belong in Cyphornis
  • Pelagornis (Early Miocene of Armagnac, France – Early Pleistocene of Ahl al Oughlam, Morocco) – may include Pseudodontornis longirostris, Palaeochenoides
  • Pelagornithidae gen. et spp. indet. (Early? Miocene – Early Pliocene of eastern US) – 2–3 species? Pelagornis?[54]
  • cf. Osteodontornis (Capadare Middle Miocene of Cueva del Zumbador, Venezuela)[55]
  • cf. Osteodontornis/Pelagornis (?Middle/Late Miocene of North Canterbury, New Zealand)[56]
  • cf. Pelagornis (Bahía Inglesa Middle Miocene of Chile – Early Pliocene of Chile and Peru) – 2 species?[57]
  • cf. Osteodontornis (Pisco Middle Miocene –? Early Pliocene of Peru) – 2 species?[58]
  • "Pseudodontornis" stirtoni (Miocene or Pliocene of Motunau Beach, New Zealand) – sometimes Neodontornis
  • Pelagornithidae gen. et sp. indet. (Yushima Early Pliocene of Maesawa, Japan) – Osteodontornis?[59]
  • cf. "Pseudodontornis" stirtoni (Tangahoe Mudstone Middle Pliocene of Hawera New Zealand)[60]
  • Pelagornithidae gen. et sp. indet. (Dainichi Early Pleistocene of Kakegawa, Japan) – Osteodontornis?[61]
  • Pelagornis sp. (Late Pliocene of California, US: Boessenecker and Smith; 2011)

Some other

Manu and Protopelicanus.[62]

Footnotes

  1. ^ Bourdon (2005), Mayr, G. (2008), Boessenecker and Smith (2011)
  2. ^ Gerald Mayr, G. et al. (2019) Oldest, smallest and phylogenetically most basal pelagornithid, from the early Paleocene of New Zealand, sheds light on the evolutionary history of the largest flying birds.
  3. ^ Hopson (1964), Olson (1985: pp. 199–201), Bourdon (2005), Geraads (2006), Mayr (2009: pp. 55,59), Mlíkovský (2009)
  4. "Pseudodontornis" stirtoni
     is the only notable exception: Scarlett (1972) contra Mayr (2009: p. 59)
  5. ^ Published in a thesis and hence a nomen nudum. Also, Odontoptila is already used for a geometer moth genus: ICZN (1999), uBio (2005)
  6. ^ Scarlett (1972), Olson (1985: pp. 199–200), Bourdon (2005, 2006), Mayr (2008, 2009: pp. 57,59), Mayr et al. (2008)
  7. ^ Meunier (1951), Hopson (1964), Olson (1985: p. 200) Mayr (2008, 2009: p. 58)
  8. ^ Woodward (1909): pp. 86–87, Hopson (1964), Olson (1985: p. 142), Bourdon (2005), Mayr (2009: p. 58), Mayr et al. (2008)
  9. ^ Olson (1985: pp. 194–195), Mayr (2008), GG [2009]
  10. Tusoteuthis longa
    were eaten by the first of these birds: PD [2009]
  11. Blennioidei (true blennies) and perhaps eelpouts (Zoarcidae) are surmised to be of similar age given the (Late) Cretaceous origin of their or related lineages. If pseudotooth birds are of Cretaceous origin, as is likely, their initial prey might have included Enchodontoidei which became extinct at the end of the Mesozoic
    : PD [2009]
  12. ^ Hopson (1964), Olson (1985: pp. 200–201), Ono (1989), del Hoyo et al. (1992: pp. 198,204), Warheit (1992, 2001), Rincón R. & Stucchi (2003), Sluijs et al. (2006), Chávez et al. (2007), Mayr (2008, 2009: pp. 56–58,217–218)
  13. ^ E.g. Desmatophoca, Gomphotaria, Imagotaria, Pelagiarctos and Pliopedia. Some of these had four tusks, and some others had no tusks at all: PD [2009]
  14. ^ Begon et al. (2005): pp. 123–124, Mayr (2009: pp. 217–218), PD [2009]
  15. ^ Olson (1985: pp.195–199), del Hoyo et al. (1992), Olson & Rasmussen (2001), Price & Clague (2002), Mlíkovský (2002: pp.81–83, 2003), Rincón R. & Stucchi (2003), Sluijs et al. (2006), Mayr (2009: pp. 6,56)
  16. ^ Warheit (1992, 2001), Olson & Rasmussen (2001), Geraads (2006), Chávez et al. (2007), Mayr (2009: pp. 217–218), GG [2009], Mlíkovský (2009)
  17. megalodon shark
    (Carcharocles megalodon) would probably have found even the largest pseudotooth bird to be not worth the effort of hunting.
  18. ^ Olson & Rasmussen (2001), Purdy et al. (2001)
  19. S2CID 226263538
    .
  20. ^ a b c del Hoyo et al. (1992)
  21. ^ Short-tailed waterfowl and "higher waterbirds" often have light or white tails: del Hoyo et al. (1992)
  22. ^ Olson (1985: p. 198), Mlíkovský (2002: p. 81), Mayr (2009: pp. 55–59)
  23. ^ Lanham (1947), Wetmore (1956: pp. 12–14), Brodkorb (1963: pp. 241,262–264), Hopson (1964), Olson (1985: pp. 195–199), Mlíkovský (2002: p. 81), Mayr (2009: p. 59)
  24. ^ Lanham (1947), Brodkorb (1963: pp. 248–249, 1967: p. 141-143), Olson (1985: p. 195), Mlíkovský (2002: pp. 78,81–83), Mayr (2008, 2009: p. 59)
  25. ^
    S2CID 203884619
    .
  26. ^ Woodward (1909: p.87), Brodkorb (1967: p. 142), Olson (1985: pp. 195,199), Bourdon (2005), Christidis & Boles (2008: p. 100), Mayr (2009: p. 59)
  27. ^ Bourdon (2005), Mayr (2008), Mayr (2009: p. 59)
  28. ^ Bourdon (2005)
  29. ^ Wetmore (1917), Hopson (1964), Olson (1985: pp. 199–200), González-Barba et al. (2002), Bourdon (2005), Christidis & Boles (2008: pp.100,105), Mayr (2008, 2009: p. 59), Mayr et al. (2008), TZ [2009]
  30. Laornis edvardsianus
    : Mayr (2009: p. 21)
  31. ^ Bourdon (2005), Livezey & Zusi (2007), Mayr (2009: p. 59)
  32. ^ Stone (1918)
  33. ^ Howard (1957), Hopson (1964), Brodkorb (1967: p. 142), Wetmore (1917), Bourdon (2005), Mayr (2008, 2009), Mayr et al. (2008), TZ [2009]
  34. S2CID 86572964
    .
  35. S2CID 254099216
    .
  36. ^ Olson (1985: pp.194–195), Mayr (2008), Mayr (2009: pp. 55–59)
  37. ^ Olson (1985: pp.195–199), Mlíkovský (2002: pp. 81–84), Mayr (2009: pp. 55–59)
  38. OCP and Rhinopolis Association
    collections. The smallest pseudotooth bird known as of mid-2009: Bourdon (2005, 2006), Mayr (2009: p. 56)
  39. ^ González-Barba et al. (2002), Mlíkovský (2002: p. 81), Mayr (2009: p. 57)
  40. MHN-UABCS Te5/6–517. Distal humerus end of a small pseudotooth bird – about the size of a brown pelican (Pelecanus occidentalis) – found in the Tepetate Formation near El Cien (Baja California Sur, Mexico
    ): González-Barba et al. (2002)
  41. ^ A piece of humerus shaft of a large species: Stilwell et al. (1998)
  42. ^ A mid-sized species, at least in part formerly in Argillornis: Brodkorb (1963: pp.248–249), Mayr (2009: p. 56), Mlíkovský (2002: p. 83, 2009)
  43. ^ A large species: Bourdon (2006), Mayr (2009: p.56)
  44. ^ One large, one small upper and one small lower jaw piece: Olson (1985: pp.196,199), Tonni (1980), Tonni & Tambussi (1985), Stilwell et al. (1998), Mayr (2009: p. 58)
  45. MP19 (Priabonian
    ). No further details given: Mlíkovský (2002: p.81)
  46. ^ Beak pieces: Mayr (2009: p. 56)
  47. ^ Mlíkovský (2002: p. 81)
  48. ^ As Argillornis: Goedert (1989)
  49. LACM 128462, a mostly complete proximal end of a left ulna from the Keasey Formation of Washington County, Oregon; presumably also LACM 127875, fragments of the proximal humerus ends, the proximal right ulna and radius of a single individual from the Pittsburg Bluff Formation near Mist
    . A huge species, perhaps the largest pseudotooth bird known. Warheit (2001) lists 2 species and gives "Middle Eocene" as age, but this is wrong: Goedert (1989), González-Barba et al. (2002), Mayr (2009: p. 57)
  50. phalanx: Mlíkovský (1996, 2002: p. 269), Mayr (2009: p.31). "E. helveticus" is lapsus
    .
  51. ^ A bill tip from the Iwaki Formation of Ogawa in Iwaki City, and additional material from the Kishima Group of Kyushu: Ono (1989), Matsuoka et al. (1998), Mayr (2009: p. 58)
  52. ^ A large species, comparable to Osteodontornis and Pelagornis in size: Warheit (2001)
  53. ^ Distal left humerus end and some wing bone fragments. "Early Miocene" age in Warheit (2001) is probably in error: Matsuoka et al. (1998), González-Barba et al. (2002), Mayr (2009: p.58)
  54. USNM
    476044 is smallish and may have been from a third species: Olson (1985: p.198), Rasmussen (1998), Olson & Rasmussen (2001)
  55. MBLUZ-P-5093, a very large premaxilla
    piece: Rincón R. & Stucchi (2003)
  56. CMNZ AV 24,960, a proximal (initially misidentified as distal
    ) humerus piece of a large species: Scarlett (1972), Olson (1985: p.199), Mlíkovský (2002: p.84)
  57. MNHN has a proximal carpometacarpus and right humerus ends from the Pisco Formation
    : Walsh (2000), Walsh & Hume (2001), Chávez & Stucchi (2002), Rincón R. & Stucchi (2003), Chávez et al. (2007)
  58. atlas vertebra), MUSM 666 (proximal right humerus head), MUSM 667 (proximal ulna) of a bird slightly smaller than Pelagornis miocaenus; formerly assigned to Pseudodontornis in error. The well-preserved skull unveiled in 2009 also shows Osteodontornis-like "teeth" but was apparently of a larger bird: Palmer (1999: p.180)[verification needed
    ], Chávez & Stucchi (2002), Chávez et al. (2007), GG [2009]
  59. ^ A fragmentary right humerus: Ono (1989), Matsuoka et al. (1998), González-Barba et al. (2002)
  60. ^ Proximal right radius (McKee collection A080 183) and distal right humerus (McKee collection A111 182) of a largish species: McKee (1985), Goedert (1989)
  61. ^ Specimen MFM 1801, a distal right femur of a large species. Initially misidentified as an albatross: Ono (1980, 1989), Matsuoka et al. (1998)
  62. ^ Olson (1985: pp.173,202,208), Mlíkovský (2002: pp.269–270), Mayr (2009: p.21,31,77,80)

References

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