Aage Kristian Olsen Alstrup

Var krokodillenes forfedre varmblodige?

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[Were crocodiles ancestors endothermic?] There are several anatomical and physiological aspects that distinguish crocodiles from other reptiles - including having a four-chambered heart like mammals and birds. This has long puzzled researchers as living crocodilians differ from other ectothermic animals. The reason may be that the ancestors of crocodiles were active, endothermic animals and eventually became ectothermic when they became ambush predators living in water. This hypothesis was proposed by a research team more than a decade ago, and is supported by the presence of the foramen of Panizza between the right and left aortic arches. This foramen indicates a fundamental shift from complete blood separation (endothermic characteristics) to autonomic shunting (ectothermic characteristics). Furthermore, present-day lung function and bone structure indicate that crocodiles may have been endothermic. This article discusses the anatomical, physiological and palaeontological aspects of this hypothesis, but concludes that it will probably not be possible definitely to test the hypothesis.
Original languageNorwegian
JournalFAUNA - tidsskrift for Norsk Zoologisk Forening
Publication statusPublished - 2 Feb 2017

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