Named By: S. L. Olson - 1977.
Classification: Chordata, Aves, Suliformes, Fregatidae, Fregatidae.
Species: L. azygosternon (type), L. hasegawai, L. hutchisoni.
Size: Wingspan ranges from about 100-120 centimetres long.
Known locations: USA, Wyoming - Green River Formation, Wasatch Formation.
Time period: Ypresian - Eocene.
Fossil representation: Several individuals, some almost complete and with feather impressions.
is a genus of bird that many have commented on about its similarity to
modern frigatebirds (genus Fregata), however
there are a number
of differences. First and foremost is the obvious fact that
Limnofregata lived inland around freshwater,
frigatebirds live by the sea. There, frigatebirds rely upon soaring
as a main method of flight, but Limnofregata
would not have been able
to do this, and probably relied upon a greater amount of flapping
to stay aloft. This also means that there probably was no
difference in wing size between males and females, like what we see
in frigatebirds so that males and females can coexist albeit in
difference zones of the coastline. Modern frigate birds are also
known for having a brightly coloured throat pouch that can be inflated
and used in display. However the neck vertebrae of Limnofregata
differ to those of frigatebirds, and offer no indication that
Limnofregata also had a throat pouch.
A further area of difference between Limnofregata and frigatebirds is that the bill of Limnofregata is in proportion notably shorter than that seen in frigatebirds, and also lacked the hook tip. Despite this Limnofregata is thought to have been a piscivorous bird focusing its attentions upon eating the smaller fish that are known from the Green River Formation such as Diplomystus and Knightia. Overall, despite some superficial similarities to frigatebirds, Limnofregata is thought to have lived more like a gull.
- A Lower Eocene frigatebird from the Green River Formation of Wyoming (Pelecaniformes: Fregatidae). - Smithsonian Contributions to Paleobiology 35:1-33. - S. L. Olson - 1977.
- A new species of Limnofregata (Pelecaniformes: Fregatidae) from the Early Eocene Wasatch Formation of Wyoming: implications for palaeoecology and palaeobiology. - Palaeontology: 1–11. - Thomas A. Stidham - 2014.