Plotopteridae

Plotopteridae[1] is an extinct family of flightless seabirds with uncertain placement, generally considered as member of order Suliformes.[2] They exhibited remarkable convergent evolution with the penguins, particularly with the now extinct giant penguins.[3][4] 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.[5] Plotopterids are regarded as closely related to Anhingidae (darters) and Phalacrocoracidae (cormorants).[2] On the other hand, there is a theory that this group may have a common ancestor with penguins due to the similarity of forelimb and brain morphology.[2][6][7] However, the endocast morphology of stem group Sphenisciformes differs from both Plotopteridae and modern penguins.[8]

Plotopterids
Temporal range: EoceneMiocene
~
Copepteryx
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Class: Aves
Order: Suliformes
Family: Plotopteridae
Howard, 1969
Genera

Their fossils have been found in California, Oregon,[9] Washington,[10][11] British Columbia,[12] Hokkaido, Tōhoku, Chūbu, Kyushu.[13] They seem to have evolved on arctic islands during the mid-Eocene, spreading southwards with the formation of kelp forests [14] They ranged in size from that of a large cormorant (such as a Brandt's cormorant), to very large size, with femur length two times longer than emperor penguin.[2] 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[15] from the late Oligocene lower part of the Pysht Formation in Washington State. More fossils of T. hildegardae have since been described [16][17] and included some of the first known examples of borings made by the marine bone-eating worm Osedax in bird bones.[18]

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. Mori, Hirotsugu; Miyata, Kazunori (2021). "Early Plotopteridae Specimens (Aves) from the Itanoura and Kakinoura Formations (Latest Eocene to Early Oligocene), Saikai, Nagasaki Prefecture, Western Japan". Paleontological Research. 25 (2): 145–159. doi:10.2517/2020PR018. ISSN 1342-8144. S2CID 233029559.
  3. 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. S2CID 12404154.
  4. Olson, Storrs L. & Hasegawa, Yoshikazu (1996). "A new genus and two new species of gigantic Plotopteridae from Japan (Aves: Pelecaniformes)". J. Vertebr. Paleontol. 16 (4): 742–751. doi:10.1080/02724634.1996.10011362.
  5. Tatsuro et al., New Skeletal Remains of Plotopterids from Japan, SVP 2015
  6. 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.
  7. 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. S2CID 83729696.
  8. Mayr, Gerald; Goedert, James L.; Pietri, Vanesa L. De; Scofield, R. Paul (2021). "Comparative osteology of the penguin-like mid-Cenozoic Plotopteridae and the earliest true fossil penguins, with comments on the origins of wing-propelled diving". Journal of Zoological Systematics and Evolutionary Research. 59 (1): 264–276. doi:10.1111/jzs.12400. ISSN 1439-0469.
  9. 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.
  10. 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. S2CID 88129671.
  11. 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.
  12. 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.
  13. "西海市から発見された世界最古級のペンギンモドキの化石について" (PDF) (Press release). 西海市教育委員会、蒲郡市教育委員会、福井県立恐竜博物館. 2020-08-18. Retrieved 2022-02-26.
  14. Mayr, G.; Goedert, J. (2021). "New late Eocene and Oligocene plotopterid fossils from Washington State (USA), with a revision of "Tonsala" buchanani (Aves, Plotopteridae). Journal of Paleontology". (e1163573) online preview: 10.1017/jpa.2021.81. doi:10.1017/jpa.2021.81. S2CID 240582610. {{cite journal}}: Cite journal requires |journal= (help)
  15. 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. doi:10.5962/p.208144. S2CID 4803730.
  16. 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.
  17. 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. doi:10.1016/j.geobios.2017.12.006.
  18. Kiel, Steffen; Kahl, W.-A.; Goedert, James L. (2011). "Osedax borings in fossil marine bird bones". Naturwissenschaften. 98 (1): 51–55. doi:10.1007/s00114-010-0740-5. PMC 3018246. PMID 21103978.
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