Plotopteridae[1] is anextinctfamily of flightlessseabirds with uncertain placement, generally considered as member of orderSuliformes.[2] They exhibited remarkableconvergent evolution with thepenguins, particularly with the nowextinct giant penguins.[3][4] That they lived in theNorth 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 toAnhingidae (darters) andPhalacrocoracidae (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 ofstem groupSphenisciformes differs from both Plotopteridae and modern penguins.[8]
The second species to be named from rocks along the eastern Pacific Ocean wasTonsala hildegardae[15] from the late Oligocene lower part of the Pysht Formation in Washington State. More fossils ofT. hildegardae have since been described[16][17] and included some of the first known examples of borings made by the marine bone-eating wormOsedax in bird bones.[18]
The earliest known member of the family,Phocavis maritimus lived in the lateEocene, 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 thegiant penguins of the Southern Hemisphere, which also coincided with the radiation of theseals anddolphins, has led to speculation that the expansion ofmarine mammals was responsible for the extinction of the Plotopteridae, though this has not been formally tested.
^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.
^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.Bibcode:2016JVPal..36E3573M.doi:10.1080/02724634.2016.1163573.S2CID88129671.
^Mayr, Gerald; Goedert, James L. (2018). "First record of a tarsometatarsus ofTonsala hildegardae (Plotopteridae) and other avian remains from the late Eocene/early Oligocene of Washington State (USA)".Geobios.51 (1):51–59.Bibcode:2018Geobi..51...51M.doi:10.1016/j.geobios.2017.12.006.
^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:224–236.doi:10.1017/jpa.2021.81.S2CID240582610.
^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.
^Mayr, Gerald; Goedert, James L. (2017). "First record of a tarsometatarsus ofTonsala hildegardae (Plotopteridae) and other avian remains from the late Eocene/early Oligocene of Washington State (USA)".Geobios.51 (1):51–59.Bibcode:2018Geobi..51...51M.doi:10.1016/j.geobios.2017.12.006.
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.Bibcode:2016JVPal..36E3573M.doi:10.1080/02724634.2016.1163573.S2CID88129671.
