A field guide to mesozoic birds and other winged dinosaurs
Gonzalez’s Vulture Roost Robber Buitreraptor gonzalezorum Time: 94 Ma ago Location: Neuquen, Argentina Habitat: Calenderos Formation Size: WS >70cm (2.3ft); BL 1.3m (4.4ft); TL unknown Features: Small, flightless unenlagiines w/ relatively large wings. Snout extremely long & narrow. wing claws short & digits nearly equal in length. Hand unusually short relative to very long humerus & radius/ulna. Relatively long legs. Biology: The very long, narrow snout suggests a piscivorous diet. Probably waded or stalked the shores of shallow waterways to ambush fish & small terrestrial vertebrates. Cabaza’s Southern Thief Austroraptor cabazai Time: 70 Ma ago Location: Rio Negro, Argentina Habitat: Allen Formation Size: WS unknown; BL ~5m (16.4ft); TL unknown Features: Giant flightless unenlagiines. Snout long & narrow, w/ fluted teeth. Prominent ridge above the eyes. Wings very small & probably not readily visible among body feathers when folded. Legs long, w/ flat sickle claw on flattened second toe. Biology: Probably a generalist preferring fish, stalking river & lake shores like modern herons. Fluted teeth would have helped grasp slippery prey. Sickle claw may have helped tear larger prey or carcasses into manageable pieces. The extinction of the spinosaurids about 10 Ma prior may have allowed the unenlagiines, which were similar in ecology but much smaller, to have evolved larger sizes as they expanded into empty ecological niches. Omnogov Mahakala Mahakala omnogovae Time: 75 Ma ago Location: Omnogov, Mongolia Habitat: Tugriken Shireh, Djadochta Formation, highly arid Gobi Desert scrub and dune fields. Size: WS >20cm (7.8in); BL 65cm (2.1ft); TL unknown Features: Tiny, ground-dwelling deinonychosaurians. Wings extremely reduced & possibly not visible externally. Legs slender. Tail shallow but very wide & flattened in appearance. Internally characterized by a flattened, broad ulna & large femoral crest. Biology: This species preserves some features of the earliest deinonychosaurians, such as very small size, but others, such as the extremely small wings, may represent reversals. Probably foraged for small prey among scrub or buried under the sand. As a very late surviving, terrestrial member of its lineage (possibly an unenlagiine) with a foraging lifestyle, the plumage is restored similarly to modern small flightless birds like kiwi. 96
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