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The beak, bill, or rostrum is an external anatomical structure found mostly in birds, but also in turtles, non-avian dinosaurs and a few mammals. A beak is used for pecking, grasping, and holding (in probing for food, eating, manipulating and carrying objects, killing prey, or fighting), preening, courtship, and feeding young.
Presented above are the most well-documented examples of modern adaptive radiation, but other examples are known. Populations of three-spined sticklebacks have repeatedly diverged and evolved into distinct ecotypes. [26] On Madagascar, birds of the family Vangidae are marked by very distinct beak shapes to suit their ecological roles. [27]
The beak of the sub-group Certhidea, is shown in Fig. 4. The beak of Cactornis is somewhat like that of a starling, and that of the fourth subgroup, Camarhynchus, is slightly parrot-shaped. Seeing this gradation and diversity of structure in one small, intimately related group of birds, one might really fancy that from an original paucity of ...
The colour of a bird's beak results from concentrations of pigments—primarily melanins and carotenoids—in the epidermal layers, including the rhamphotheca. [39] In general, beak colour depends on a combination of the bird's hormonal state and diet. Colours are typically brightest as the breeding season approaches and palest after breeding. [40]
Some water birds (e.g. wading birds) are more terrestrial while others (e.g. waterfowls) are more aquatic, and their adaptations will vary depending on their environment. These adaptations include webbed feet, beaks, and legs adapted to feed in the water, and the ability to dive from the surface or the air to catch prey in water.
Ichthyornis fossils were first unearthed in the 1870s, but the new ones from Kansas and Alabama chalk deposits, reveal far more about it than once known.
The beak, bill, or rostrum is an external anatomical structure of birds which is used for eating and for preening, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young. Although beaks vary significantly in size, shape and color, they share a similar underlying structure.
The monotreme platypus has what looks like a bird's beak (hence its scientific name Ornithorhynchus), but is a mammal. [38] However, it is not structurally similar to a bird beak (or any "true" beak, for that matter), being fleshy instead of keratinous. Red blood cells in mammals lack a cell nucleus.