The hot question of whether dinosaurs were warm-blooded like birds and mammals or cold blooded like reptiles, fish and amphibians finally has a good answer. Dinosaurs were in fact somewhere in between.
The study, published in the journal Science, assessed 21 species of dinosaurs including super predators Tyrannosaurus and Allosaurus, long-necked Apatosaurus, duckbilled Tenontosaurus and bird-like Troodon as well as a range of mammals, birds, bony fish, sharks, lizards, snakes and crocodiles.
“Our results showed that dinosaurs had growth and metabolic rates that were actually not characteristic of warm-blooded or even cold-blooded organisms. They did not act like mammals or birds nor did they act like reptiles or fish,” said University of Arizona evolutionary biologist and ecologist Brian Enquist.
Photo: Reuters
照片：路透社
“Instead, they had growth rates and metabolisms intermediate to warm-blooded and cold-blooded organisms of today. In short, they had physiologies that are not common in today’s world.”
University of New Mexico biologist John Grady said the idea that creatures must be either warm-blooded or cold-blooded is too simplistic when looking over the vast expanse of time. Like dinosaurs, some animals alive today like the great white shark, leatherback sea turtle and tuna do not fit easily into either category, Grady added.
(Reuters)
恐龍是否像鳥或哺乳類是溫血的，還是像爬蟲類、魚與兩棲類是冷血的熱門問題，最終有了好答案。事實上，恐龍是介於兩者之間。
這項發表在《科學》期刊的研究，評估包括超級掠食者暴龍和異特龍、長頸的雷龍、禽龍類的腱龍以及類似鳥的鋸齒龍等二十一種恐龍，以及一系列哺乳類、鳥類、硬骨魚、鯊魚、蜥蜴、蛇類與鱷魚。
「我們的結果顯示，恐龍的成長與代謝率實際上非屬典型的溫血或甚至冷血生物。牠們的運作不像哺乳類或鳥類，也不像爬蟲類或魚類。」亞歷桑納大學演化生物學家與生態學家恩奎斯特說。
「他們反而具有介於現今溫血與冷血生物的成長率與新陳代謝。簡言之，他們的生理機能在當今世界並不常見。」
新墨西哥大學生物學家葛雷迪表示，當檢視浩瀚的時間時，恐龍一定不是溫血就是冷血的觀點過於簡單。如同恐龍，現存的一些動物，如大白鯊、稜皮龜與鮪魚無法輕易的劃分為任一類別，葛雷迪補充說。
（路透／翻譯：魏國金）
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