Comments on: The Evolution of the Crocodylia http://afarensis.blogsome.com/2005/06/27/the-evolution-of-the-crocodylia/ Exploring the World Around Us Thu, 28 Aug 2008 08:39:49 +0000 http://wordpress.org/?v=1.5.1-alpha by: afarensis http://afarensis.blogsome.com/2005/06/27/the-evolution-of-the-crocodylia/#comment-60 Thu, 10 Nov 2005 12:49:18 +0000 http://afarensis.blogsome.com/2005/06/27/the-evolution-of-the-crocodylia/#comment-60 I am inclined to be skeptical that crocodilians were ever warm-blooded. Most of the features you mention are adapatations to life in the water. I am inclined to be skeptical that crocodilians were ever warm-blooded. Most of the features you mention are adapatations to life in the water.

]]> by: Philip Chalmers http://afarensis.blogsome.com/2005/06/27/the-evolution-of-the-crocodylia/#comment-57 Wed, 09 Nov 2005 17:27:45 +0000 http://afarensis.blogsome.com/2005/06/27/the-evolution-of-the-crocodylia/#comment-57 The other notable thing about crocodilians is that they are cold-blooded but have a lot of warm-blooded features - palate (allows breathing while eating), 4-chambered heart (fewer chambers means inefficient oxygenation of blood), piston mechanism to pump the lungs, ability to move with limbs erect rather than sprawling. These warm-blooded features in a cold-blooded animal are a puzzle in archosaur evolution. Why would natural selection have favoured them in an aminal which remained cold-blooded?And you have to believe that earlier archosaurs were also fairly warm-blooded. Fossil evidence indicates that the evolution of warm-bloodedness in the mammal-like reptiles was a slow business which started in the mid-Permian with gradual development of palates and an even more gradual trend to wards erect limbs. So it's hard to believe that warm-bloodedness developed much faster in archosaurs. Unfortunately the fossil record for early archosaurs is very poor - <a href="http://www.nrf.ac.za/sajs/abaug00f.stm" rel="nofollow">only 2 Permian archosaurs are known</a>.So the view is gaining ground that crocodilians were originally fairly warm-blooded cursorial carniovores, like your slim, leggy <i>Terristrisuchus</i>, and gave up warm-bloodedness when something (? dinosaurs) forced all surviving crocodilians into the role of aquatic ambush predators. The other notable thing about crocodilians is that they are cold-blooded but have a lot of warm-blooded features - palate (allows breathing while eating), 4-chambered heart (fewer chambers means inefficient oxygenation of blood), piston mechanism to pump the lungs, ability to move with limbs erect rather than sprawling. These warm-blooded features in a cold-blooded animal are a puzzle in archosaur evolution. Why would natural selection have favoured them in an aminal which remained cold-blooded?And you have to believe that earlier archosaurs were also fairly warm-blooded. Fossil evidence indicates that the evolution of warm-bloodedness in the mammal-like reptiles was a slow business which started in the mid-Permian with gradual development of palates and an even more gradual trend to wards erect limbs. So it’s hard to believe that warm-bloodedness developed much faster in archosaurs. Unfortunately the fossil record for early archosaurs is very poor - only 2 Permian archosaurs are known.So the view is gaining ground that crocodilians were originally fairly warm-blooded cursorial carniovores, like your slim, leggy Terristrisuchus, and gave up warm-bloodedness when something (? dinosaurs) forced all surviving crocodilians into the role of aquatic ambush predators.

]]> by: Modulator http://afarensis.blogsome.com/2005/06/27/the-evolution-of-the-crocodylia/#comment-3 Fri, 01 Jul 2005 16:07:49 +0100 http://afarensis.blogsome.com/2005/06/27/the-evolution-of-the-crocodylia/#comment-3 <strong>Friday Ark</strong> Cats, Dogs, Spiders and ? every Friday. We'll post links to sites that have Friday (plus or minus a few days) photos of their chosen animals as I see them (photoshops at our discretion and humans only in supporting roles). Leave a comment or trackback... Friday Ark

Cats, Dogs, Spiders and ? every Friday. We’ll post links to sites that have Friday (plus or minus a few days) photos of their chosen animals as I see them (photoshops at our discretion and humans only in supporting roles). Leave a comment or trackback…

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