An anonymous submission asked for a “live bearing bird”:
Rimurimuornis ovovivipara is a future descendant of the broad-billed moa, in a timeline where these Aotearoan birds weren’t hunted to extinction.
About 2m long (~6’6″), this fully aquatic bird grazes in kelp forests and seagrass meadows. It’s a rather slow swimmer, propelled solely by its large flipper-like feet – because like all moa it completely lacks wings.
Its ancestors’ laid incredibly thin-shelled eggs, and a combination of reducing the hard shell away even further to a more leathery state, then increasing egg retention time inside females’ bodies, has led to this lineage evolving an ovoviviparous form of live birth at sea.
It also has long ribbon-like feathers along its back that mimic the appearance of seaweed fronds. While terrestrial moa have few large predators to worry about, Rimurimuornis has to contend with sharks, orca-like whales, and leopard seal-like pinnipeds, and if its camouflage fails its primary tactic to discourage attacks is defensive defecation.