A field guide to mesozoic birds and other winged dinosaurs
Share Embed Flag
Download ePaper

A field guide to mesozoic birds and other winged dinosaurs

monik.pc
19.07.2019 Views

Spatulate Ancient Beak Archaeorhynchus spathula Time: ~125 Ma ago Location: Liaoning, China Habitat: Yixian Formation Size: WS 40cm (1.3ft); BL 17cm (6in); TL 21cm (8in) Features: Head small & round w/ thin, toothless jaws tipped w/ flat beak. Neck short. Wings very long. Ulna ~ ¾ torso length. Humerus slightly shorter. Manus length unknown but very long. Primaries up to 10cm long, w/ long secondaries & rounded wing. Small claw on at least major digit. Legs short and stocky. Femur and tibia each ~ ¾ ulna length. Tarsus short, less than half tibia length. Toes long w/ small, weak claws. Rectrices long (up to 4cm) & arranged in a fan. Biology: Terrestrial, but probably not specialized waders. Small spoon-shaped bill indicates semi-aquatic, possibly surface-swimming lifestyle. However, the round bill w/o pointed tip supported by a predentary rules out a specialized ability for catching fish or other small aquatic animals. Instead, presence of gizzard stones may imply a primarily herbivorous diet of water plants, larvae, etc. Long-crested Hongshan Bird Hongshanornis longicresta Time: 124.6 Ma ago Location: Liaoning, China Habitat: Lower Yixian Formation Size: WS 35cm (1.1ft); BL 13cm (5in); TL 18cm (7in) Features: Head small & round, long feathers possibly forming large crest. Snout short & slender w/ beaked tip. Few very small teeth behind beak in upper & possibly lower jaws. Wings very long, narrow & pointed, but w/ small forelimb (humerus, ulna & manus ~ same length as skull). Large claws on alular and major digits, minor digit fused to major digit. Legs very long & slender, w/ very long tibia & tarsus longer than toes. Hallux small & non-grasping. Toes long & slender, w/ small, weakly curved claws. Tail fan w/ at least four rectrices at ~5cm long. Biology: Likely wading birds due to long tibia & tarsus. Long legs allowed excursions into moderately deep areas of marshes or lake margins. Long narrow wings typical of aquatic birds; this, combined with the wishbone shape, is consistent with a dynamic soaring flight style. Straight, pointed beak, with small teeth would have made these less efficient at catching fish than toothed forms. Instead, bill may have been an adaptation for aquatic insectivory or mud-probing. Hou’s Long-shank Bird Longicrusavis houi Time: 122 Ma ago Location: Liaoning, China Habitat: Upper Yixian Formation Size: WS 40cm (1.3ft); BL 15cm (6in); TL ~20cm (8in) Features: Similar to Hongshanornis but w/ slightly larger wings and more robust snout. Wing & leg proportions nearly identical, but w/ slightly longer humerus & more robust toes/claws. Differed in aspects of breastbone. Biology: Similar in ecology to earlier species H. longicresta. Some place these together in a clade, Hongshanornithidae (w/ possibly more advanced Parahongshanornis). L. houi may be descendant species of H. longicresta. Chaoyang Near Hongshan Bird Parahongshanornis chaoyangensis Time: 120 Ma ago Location: Liaoning, China Habitat: Jiufotang Formation. Temperatesubtropical swamps dominated by ginkgo and conifer trees, set among shallow lakes and stagnant waterways. Size: WS >20 cm (8in); BL ~12cm (5in); TL unknown Features: Head unknown. Neck short. Wings shorter relative to legs than relatives. All major wing segments about the same length. Alular digit short & robust w/ large claw. Smaller, thinner claw on major digit. Legs long w/ long tibia, tarsus longer than toes. Minor digit short & fused to major. Toes thin w/ short, slightly curved claws. Hallux very small. Biology: Some internal anatomical features, such as a thick, U-shaped wishbone, led researchers to initially classify this species among the hongshanornithids. However, some preliminary cladistic analyses suggest these may have been more advanced euornitheans instead (Cau 2012). 146

147

147

logo

products

Resources

Company

Terms of service
Privacy policy
Cookie policy
Cookie settings
Imprint
Change language
Made with love in Switzerland
© 2024 Yumpu.com all rights reserved

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!