TABLE 1. Temporal and geographic record of the Family Plotopteridae.
| Genus and species | Formation and location | Age | Source |
| Plotopterum joaquinensis |
Pyramid Hill Sand M., Jewett Sand F., California |
Late Oligocene (24-25 Ma) |
Howard (1969), Scheirer and Magoon (2007) |
| Plotopterum sp. |
Yamanouchi M., Akeyo F., Japan |
Early Miocene (16-17 Ma) |
Olson and Hasegawa (1985), Sasao et al. (2011) |
| Tonsala hildegardae |
Pysht F., Washington |
Early Oligocene |
Olson (1980), Goedert and Cornish (2002) |
| T. buchanani |
Pysht F., Washington Makah F., Washington |
Early Oligocene
Late Eocene |
Goedert and Cornish (2002), Dyke et al. (2011) |
| Tonsala? sp. |
Yamaga F., Japan |
Early Oligocene (ca. 30-32 Ma) |
Ozaki and Hamasaki (1991), Olson and Hasegawa (1996) |
| Stemec suntokum |
Sooke F., British Columbia |
Late Oligocene
(24.1-24.8 Ma) |
Prothero et al. (2008), this study |
| Copepteryx hexeris |
Ainoshima F. (~Yamaga F.), Japan Yamaga F., Japan Asagai F., Japan |
Early Oligocene
Early Oligocene
Early Oligocene |
Ozaki and Hamasaki (1991), Okada (1992), Olson and Hasegawa (1996), Kurita (2004) |
| C. titan |
Ainoshima F. (~Yamaga F.), Japan |
Early Oligocene |
Olson and Hasegawa (1996) |
| Hokkaidornis abashiriensis |
Tokoro F., Japan |
Late Oligocene
(24-29 Ma) |
Sakurai et al. (2008) |
| Phocavis maritimus |
Keasey F., Oregon |
Late Eocene
(ca. 33.8 Ma) |
Goedert (1988), Goedert and Cornish (2002) |
TABLE 2. Proportional dimensions of coracoids among the Plotopteridae and modern waterbirds.
| Taxa | Source | Length of head1 to total length (%) | Width of sternal articulation to total length (%) |
| Plotopteridae | |||
| Stemec suntokum | RBCM.EH 2014.032.0001.001 |
23.3 | 18.0 |
| Copepteryx hexeris | Hasegawa et al. (1979) | 23.5 | 23.0 |
| Tonsala(?) sp. | Hasegawa et al. (1979) | 21.5 | 21.0 |
| Sulidae | |||
| Sula sula | RBCM 23425 | 29.3 | 46.0 |
| Anhingidae | |||
| Anhinga anhinga | UWBM 40957 | 23.6 | 26.0 |
| A. melanogaster | UWBM 62930 | 24.7 | 24.0 |
| Stem cormorants | |||
| Oligocorax sp. | Mayr (2015) | 25.3 | 27.0 |
| Nambashag billerooensis | Worthy (2011) | 25.6 | 23.9 |
| Phalacrocoracidae | |||
| Phalacrocorax harrisi | Shufeldt (1915) | 16.4 | 31.0 |
| NHMUK 1973.1.13 | 13.45 | 30.0 | |
| NHMUK 1902.1.9.12 | 15.35 | 32.0 | |
| Phalacrocorax penicillatus | RBCM 15002 | 25.7 | 24.0 |
| RBCM 12071 | 25.6 | 25.0 | |
| P. pelagicus | RBCM 23169 | 25.5 | 30.0 |
| P. auritus | RBCM 11279 | 24.3 | 28.0 |
| Spheniscidae | |||
| Eudyptula minor | UWBM 57505 | 30.0 | 29.0 |
| Spheniscus magellanicus | Livezey and Zusi (2006) | 22.9 | 29.0 |
| Spheniscus humboldti | UWBM 57504 | 28.7 | 32.0 |
| Pygoscelis antarctica | UWBM 38043 | 34.9 | 34.0 |
