FIGURE 1 in Five well-supported fossil calibrations within the "Waterbird" assemblage (Tetrapoda, Aves)

FIGURE 1. Specimens representative of two taxa that provide fossil calibrations within the waterbird assemblage. 1, Limnofregata azygosternon (USNM 22753) from the early Eocene Green River Formation represents the sister taxon (with its congener Limnofregata hasegawai) to Fregata, and calibrates the node Fregatidae + Suloidea. 2, Rhynchaeites messelensis (SMF 218) from the middle Eocene of Messel. Together with other Messel Rhynchaeites messelensis specimens and Rhynchaeites sp. (MGUH 20288) from the early Eocene Fur Formation, these represent the sister taxon to Threskiornithidae, and MGUH 20288 calibrates the node uniting Threskiornithidae and its extant sister taxon. Scale bars equal 50 mm.