After Feduccia, 1980, 1997, and Olson, 1975, 1985
<==o †Plotopteridae Howard, 1969 (pingviinisuulat) |-- †Phocavis maritimus Goedert, 1988 |--o †Tonsala Olson, 1980; L.Eoc.-E.Olig. ENAm. | |-- †T. hildegardae Olson, 1980 | `-- †T. buchanani Dyke, Wang & Habib, 2011 |--o †Copepteryx Olson & Hasegawa, 1996 | |-- †C. hexeris Olson & Hasegawa, 1996 | `-- †C. titan Olson & Hasegawa, 1996 |-- †Hokkaidornis Sakurai et al., 2008 `--o †Plotopterum Howard, 1969 |-- †P. joaquinensis |-- †P. sp.1 |-- †P. sp.2 `-- †P. sp.3
Reference(s):
- Feduccia, A., 1980: The Age of Birds.
–Harvard University Press, Cambridge, Massachusetts & London, England, 1980, IX-196 - Dyke, G. J., Wang, X. & Habib, M. B., 2011: Fossil Plotopterid Seabirds from the Eo-Oligocene of the Olympic Peninsula (Washington State, USA): Descriptions and Functional Morphology.
–Plos One: Vol. 6, #10, pp. e25672 [doi: 10.1371/journal.pone.0025672] - Feduccia, A., 1997: The Origin and Evolution of Birds.
–Yale University Press, New Haven, 1996, x-420 - Mayr, G., 2004: Tertiary plotopterids (Aves, Plotopteridae) and novel hypothesis on the phylogenetic relationships of penguins (Spheniscidae).
–JZS: Vol. 43, #1, pp. 61-71 [doi: 10.1111/j.1439-0469.2004.00291.x] - Olson, S. L., 1975: Paleornithology of St. Helena Island, South Atlantic Ocean.
–Smithsonian Contributions to Baleobiology: Vol. 23, pp. iv-49 - Olson, S. L., 1985: The fossil record of birds. 79-239.
in Farner, D., King, J. & Parkes, K. (eds.), 1985: Avian Biology. vol VIII.
–Academic Press, New York. 1985