Plotopteridae

Plotopteridae[1] is the name of an extinct family of flightless seabirds from the order Suliformes. Related to the gannets and boobies, they exhibited remarkable convergent evolution with the penguins, particularly with the now extinct giant penguins.[2][3] That they lived in the North Pacific, the other side of the world from the penguins, has led to them being described at times as the Northern Hemisphere's penguins, though they were not closely related. More recent studies have shown, however, that the shoulder-girdle, forelimb and sternum of plotopterids differ significantly from those of penguins, so comparisons in terms of function may not be entirely accurate.[4] On the other hand, there is a theory that this group may have a common ancestor with penguins due to the similarity of brain morphology, and the actual classification is not clear.[5][6]

Plotopterids
Temporal range: Eocene – Miocene
Copepteryx
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Suliformes
Family: †Plotopteridae
Howard, 1969
Genera

Copepteryx
Hokkaidornis
Klallamornis
Olympidytes
Phocavis
Plotopterum
Stemec
Tonsala

Their fossils have been found in California, Oregon,[7] Washington,[8][9] British Columbia[10] and Japan. They ranged in size from that of a large cormorant (such as a Brandt's cormorant), to being 2 m long. They had shortened wings optimised for underwater wing-propelled pursuit diving (like penguins or the now extinct great auk), and a body skeleton similar to that of the darter.

Tonsala hildegardae fossils

The second species to be named from rocks along the eastern Pacific Ocean was Tonsala hildegardae[11] from the late Oligocene lower part of the Pysht Formation in Washington State. More fossils of T. hildegardae have since been described [12][13] and included some of the first known examples of borings made by the marine bone-eating worm Osedax in bird bones.[14]

Reconstruction of Copepteryx.

The earliest known member of the family, Phocavis maritimus lived in the late Eocene, but most of the known species lived during Oligocene time, becoming extinct in the early to mid-Miocene. That they became extinct at the same time as the giant penguins of the Southern Hemisphere, which also coincided with the radiation of the seals and dolphins, has led to speculation that the expansion of marine mammals was responsible for the extinction of the Plotopteridae, though this has not been formally tested.

References
  1. Howard, H. (1969). "A new avian fossil from Kern County, California" (PDF). Condor. 71 (1): 68–69. doi:10.2307/1366050. JSTOR 1366050.
  2. Olson, Storrs L.; Hasegawa, Yoshikazu (1979). "Fossil Counterparts of Giant Penguins from the North Pacific". Science. 206 (4419): 688–689. Bibcode:1979Sci...206..688O. doi:10.1126/science.206.4419.688. PMID 17796934.
  3. Olson, Storrs L. & Hasegawa, Yoshikazu (1996). "A new genus and two new species of gigantic Plotopteridae from Japan (Aves: Pelecaniformes)". J. Vert. Paleontol. 16 (4): 742–751. doi:10.1080/02724634.1996.10011362.
  4. Tatsuro et al., New Skeletal Remains of Plotopterids from Japan, SVP 2015
  5. Kawabe, Soichiro; Ando, Tatsuro; Endo, Hideki (2014). "Enigmatic affinity in the brain morphology between plotopterids and penguins, with a comprehensive comparison among water birds". Zoological Journal of the Linnean Society. 170 (3): 467–493. doi:10.1111/zoj.12072. ISSN 1096-3642.
  6. Mayr, Gerald; Goedert, James L.; Vogel, Olaf (2015-07-04). "Oligocene plotopterid skulls from western North America and their bearing on the phylogenetic affinities of these penguin-like seabirds". Journal of Vertebrate Paleontology. 35 (4): e943764. doi:10.1080/02724634.2014.943764. ISSN 0272-4634.
  7. Goedert, James L. (1988). "A new late Eocene species of Plototpteridae (Aves: Pelecaniformes) from northwestern Oregon". Proceedings of the California Academy of Sciences. 45: 97–102.
  8. Gerald Mayr & James L. Goedert (2016). "New late Eocene and Oligocene remains of the flightless, penguin-like plotopterids (Aves, Plotopteridae) from western Washington State, U.S.A.". Journal of Vertebrate Paleontology. 36 (4): e1163573. doi:10.1080/02724634.2016.1163573.
  9. Mayr, Gerald; Goedert, James L. (2018). "First record of a tarsometatarsus of Tonsala hildegardae (Plotopteridae) and other avian remains from the late Eocene/early Oligocene of Washington State (USA)". Geobios. 51: 51–59. doi:10.1016/j.geobios.2017.12.006.
  10. Gary Kaiser; Junya Watanabe & Marji Johns (2015). "A new member of the family Plotopteridae (Aves) from the late Oligocene of British Columbia, Canada". Palaeontologia Electronica. 18 (3): Article number 18.3.52A.
  11. Olson, Storrs L. (1980). "A new genus of penguin-like pelecaniform bird from the Oligocene of Washington (Pelecaniformes: Plotopteridae)". Contributions in Science. 330: 51–57.
  12. Goedert, James L.; Cornish, John (2002). "A preliminary report on the diversity and stratigraphic distribution of the Plotopteridae (Pelecaniformes) in Paleogene rocks of Washington State, USA". Proceedings of the 5th Symposium of the Society of Avian Paleontology and Evolution, Beijing: 63–76.
  13. Mayr, Gerald; Goedert, James L. (2017). "First record of a tarsometatarsus of Tonsala hildegardae (Plotopteridae) and other avian remains from the late Eocene/early Oligocene of Washington State (USA)". Geobios. 51: 51–59.
  14. Kiel, Steffen; Kahl, W.-A.; Goedert, James L. (2011). "Osedax borings in fossil marine bird bones". Naturwissenschaften. 98: 51–55.
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