Comments on: Walking With Sea Cows

By: Daryl Domning

Daryl Domning — Mon, 25 Feb 2013 16:27:44 +0000

It should be mentioned, especially on the NGS blog, that Pezosiren was discovered and collected with the generous, decade-long support of the National Geographic Society — although they’ve never taken the credit for it that they deserve. Thanks, NGS!

By: Alex Fairchild

Alex Fairchild — Thu, 24 Jan 2013 22:58:06 +0000

I was taken aback by your dating of the end Cretaceous at 66 mya, since in my mind that number has always been 65… So I googled some, and found Renne (2008), where they improved the error margins in argon-argon dating dramatically, and were able to date that fateful day to 65.95 mya…

Thanks, Switek! You’ve enhancified my edumacation once again.

By: Ben J

Ben J — Thu, 17 Jan 2013 16:23:33 +0000

Dear chris, Good question. First, the hands and feet of Pezosiren are reconstructed on this photo (see http://www.dinosauria.org/blog/wp-content/uploads/2012/09/Figure2.jpg), second, the fact that a mammal looks like a terrestrial one does not imply that it can’t swim (think about elephant or Hippopotamus for example) and finally, rodents (the ancestor of guinea pigs for ex.) and primates (the ancestor of Howler monkeys for ex) have crossed the Atlantic sea at the Oligocene, at a time when it was larger and they were by far, more terrestrial than a stem sea cow. Thank you.

By: chris y

chris y — Thu, 17 Jan 2013 14:31:59 +0000

Puzzled. The legs and feet on that reconstruction of Pezosiren don't look as though it would be up to swimming the Atlantic, even the Eocene Atlantic. And you'd think the earlier Chambi beast would be more terrestrial if anything, if it's supposed to be ancestral to the Jamaican forms. How does this work?