A field guide to mesozoic birds and other winged dinosaurs
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A field guide to mesozoic birds and other winged dinosaurs

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19.07.2019 Views

Yang’s Zhongjian Bird Zhongjianornis yangi Time: 120 Ma ago Location: Liaoning, China Habitat: Jiufotang Formation (see above) Size: WS ~75cm (2.5ft); BL 30cm (1ft); TL unknown Features: Head small relative to body. Toothless beak short but slender & pointed. Wings large but w/ very small claws. Legs long compared to the similar confuciusornithids. Large, highly curved claws on the feet. Tail short. Biology: The presence of toothless beaks in this species & the overall similarity to Schizooura may suggest a close relationship between the two. The anatomy of the feet & their large claws imply an ability to perch, & the lack of large wing claws suggests that they were adept at launching from the ground. Li’s Split-tail Schizooura lii Time: 120 Ma ago Location: Liaoning, China Habitat: Jiufotang Formation Size: WS 65cm (2ft); BL 30cm (1ft); TL 55cm (1.8ft) Features: Head small & triangular w/ slender pointed bill. Jaws toothless & probably beaked. Neck slightly longer than skull. Wings large, w/ ulna & manus slightly longer than humerus (ulna over half the length of the torso). Very long primary & secondary feathers resulting in broad, rounded wings. Small claw on alular digit. Major digit “claw” very small, blunt, & probably internal. Minor digit fused to major. Legs long, w/ tibia longer than femur & tarsus just over half tibia length. Toes relatively short & robust w/ robust but weakly curved claws. Fan-tail long, broad & triangular when expanded, with prominent fork. Biology: Probably ground foragers, as suggested by foot anatomy. Lack of teeth acquired independently of modern birds and possibly, independently of other primitive euornitheans like Archaeorhynchus. Whereas some early euornitheans retained teeth in addition to a premaxillary & predentary beak, possibly to aid in catching & holding fish, the loss of teeth in species like this may indicate a non-piscivorous diet consisting of more grains or other plant material, &/or arthropods. The broad, forked tail would have been detrimental (or at least neutral) to flight ability & was probably used in mating displays. The strong, rounded wings are likely adaptations to flying in a densely forested environment, & possibly to help compensate for the unwieldy tail feathers. Small-toothed Jianchang Bird Jianchangornis microdonta Time: 120 Ma ago Location: Liaoning, China Habitat: Jiufotang Formation Size: WS ~60cm (ft); BL 34cm (1.1ft); TL unknown Features: Head triangular. Numerous small conical teeth in mid to rear jaws. Jaw tips beaked. Wings long w/ strong muscles anchored to keeled breastbone. Alular digit very long & strongly clawed. Major & minor digits bore very small claws. Minor digit fused to major. Feathers poorly preserved, but primary feathers over 15cm long. Legs short, w/ short tarsus ~equal to toes in length. Feet small w/ small, weakly curved claws. Biology: Evidence indicates these ate small fish including Jainichthys, & so probably foraged in or near lakes, though the relatively short tarsus & average-length tibia argue against a wading lifestyle. May have been surface swimmers or beachcombers. 148

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