Stephen Jones replied:
>And what did "Mesochynids" have as their common mammalian ancestor?>
First, I mis-spelled it on Friday. It is Mesonychid. My memory of how to
spell some of these animals is awful.
Acreodi were their ancestors and procreodonts were the ancestors of the
acreodi. (This may be a bit dated but see A. S. Romer _Vertebrate
Paleontology, 1945, p. 365-367) These were carnivores and are not anywhere
near related to the rodents.
glenn