The Triassic reptile weirdness thread

Wibbs wrote: »

I thought oxygen levels were higher then than now, or was that only later in the cretaceous?

I was not aware before reading that that oxygen levels were quite low in the Triassic, however it seem to make sense that this would be the case after the Permian mass extinction. They peaked up at about 30%(?) during the Cretaceous I think , once the great angiosperm radiation occured and they took over practically the entire world.

This thread reminds me that I have been meanng to buy this book: http://www.nap.edu/openbook.php?record_id=11630&page=1

Capt'n Midnight wrote: »

wasn't there something abut crocs hearts being leaky being advantageous to speed up digestion.

aren't the major blood vessels of the heart in mammals and birds the opposite way or something ? - did they evolve more than once ?

remember they found the heart in a dinosaur , did they ever figure anything more about it


am reminded of that blood vessel in giraffes that goes up to the head and back down again to travel a few inches , because it looped past something else earlier in evolution - it was on the channel 4 dissection of giants series

Willo the Thescelosaurus even has his own web page.

http://www.dinoheart.org/

There is some dispute as to whether or not it was was an actual dinosaur heart or not. See the section near the end of the page for the controversy details. http://en.wikipedia.org/wiki/Thescelosaurus

The evidence suggest that the four chambered heart evolved seperately in the archosaurs (Dinosaurs, Crocs, Birds) and in Mammals. As all other reptiles apart from the archosaurs have a three chambered heart and the mammalian and reptilian lineages diverged prior to the last common ancestor of the Sauropsida (All reptilian decendants including archosaurs)

Never heard that about about the Croc heart before it is a facinating change of direction. Typical evolution really, to go to to all the trouble of seperating the pulmonary circulatory system from the systemic circulatory system and then undoing all its good work.

http://en.wikipedia.org/wiki/Foramen_of_Panizza

According to the croc wiki page this serves to allow the mixture of oxygenated and deoxygenated blood in the left aorta. Because the left aortic archery goes directly to the gut, the shunting of oxygen depleted blood which is high in CO2 may serve to aid in creating stomach acid to assist in digesting bones from its prey.

Things learnt today + 1