SIMILARITIES WITH BIRDS

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As discussed in more detail in the topic ' Dinosaurs and Birds ', there are many similarities between birds and mammals (erect posture, efficient hearts, intelligence, bone structure, food requirements per size, feathers, and caring for their young).
It is now agreed that birds are probably direct descendants of dinosaurs, and may have evolved from them as early as the Jurassic period. As birds are undoubtedly warm-blooded it is not unreasonable to suppose that their ancestors were either already warm-blooded also, or developed the capability over the next 100 million years.