Name Meaning: Like Gallinula (moorhen)
Geologic Era: Eocene
Location Discovered: Wyoming (Green River Formation)
Size: 30-40 cm long (body); wingspan roughly 60 cm
Estimated Range: Western North America
Extinction Date: Middle Eocene
Gallinuloides probably behaved much like a modern duck, wading and swimming in shallow waters. It’s name means it is thought to resemble the modern moorhen, or swamp chicken. Modern moorhens do not have webbing between their toes, so it is possible that Gallinuloides shared this trait. If this is the case, it would still have been able to swim as long as its feathers were waterproof, though perhaps not as efficiently as a web-footed duck. The beak of Gallinuloides did not have teeth, a transition away from more primitive birds which did possess toothed beaks. This lack of teeth probably meant that Gallinuloides ate primarily soft, aquatic plants, though like modern ducks may have taken the occasional insect or other softer invertebrate when the opportunity arose.
Gallinuloides shared its environment with a host of other animals, some of which could have been a danger to a rather small bird. Large fish such as Mioplosus and Phaerodus inhabited the large lakes of what would become the Green River Formation, either of which would have been large enough to drag a small bird under. On land, crocodiles would have been a concern, as well as primitive canids. Gallinuloides would also have faced competition from a larger duck called Presbyornis. Both Gallinuloides and Presbyornis are possible candidates for the track makers in the Bird Trackway specimen (see Trace Fossils for full entry).
Moorhen: By David. S – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=17381956