Ashby wrote:
> I objected to his using the
drawing of _Mesonyx obtusidens_ as an ancestor of _Ambulocetus_
because the genus _Mesonyx_ does not appear in the fossil record
until the middle Eocene, several million years after the appearance
of _Ambulocetus_. Glenn has taken me to task for this claim,
arguing that _Mesonyx_ *could have* existed in the Paleocene but
not left any fossil indications of that existence.<<<
and
> As I have previously pointed out, the notion that _Mesonyx_
existed in the Paleocene is purely an assumption that is made to
harmonize the data with a preexisting conviction that _Mesonyx_ was
ancestral to _Ambulocetus_. The fossil evidence is that _Mesonyx_
appears in the middle Eocene and continues until the upper Eocence.
There is nothing in the fact that _Mesonyx_ appears *later* than
_Ambulocetus_ to suggest that _Mesonyx_ actually lived *before*
_Ambulocetus_. Indeed, the inference from that data would be to
the contrary. <<<
O. K. we will try this your way. I just got in an article yesterday by
Szalay and Gould (Bull. Amer. Mus. Nat. Hist. 132:168-170 [1966]) which you
cited in your original critique of my post. The Mesonyx obtusidens, appears
not in the mid Eocene as you claim, but in the early Eocene of Mongolia ,
North America and Europe. in plenty of time to have been the ancestor of
Ambulocetus(which appears in the mid-early Eocene 52 million years ago.).
Mesonyx obtusidens is also known as Pachyaena. This is a common occurrence
in paleontology for one species to be known under different names. It does
make things difficult.
I cited the study of Nehms and Geary who documented the speciation event of
P. coniforme to P. Christineladdae and noted that the ancestor species lived
after the daughter species arose. Ashby wrote in reply:
> In the Nehm and Geary study, none of the alleged ancestors
appeared in the fossil record after their descendants.<<<
I am sorry, Ashby, but you could not possibly have read that article. Here
are the first few sentences of the abstract. If you did read it, you didn't
read it very well.
"We document a speciation event between two species of Prunum (Marginelladae:
Gastropoda) in Pliocene strata of the northern Dominican Republic. The
ancestral species P. coniforme, is widely distributed in Mid-Pliocene of the
Dominican Republic and Jamaica, and has a range of at least 11 m.y. The
descendant species P. christineladdae, is endemic to the northern Dominican
Republic. THE ANCESTRAL SPECIES PERSISTS AFTER ITS DESCENDANT ARISES. The
transition between species is marked by stratigraphic and morphologic
intermediates. . ." Ross H, Nehm and Dana H. Geary, "A Gradual Morphologic
Transition During a Rapid Speciation Event in Marginellid Gastropods
(Neogene: Dominican Republic)" Journal. Paleont. 68(4), 1994, p. 787-795.
The emphasis was mine. The ancestor species is still found in strata 100
meters higher than the first occurrence of the daughter species. (see p.792)
And the ancestor species is found more than 100 meters below the first
appearance of the daughter.
Ashby wrote of the Nehm and Geary study:
> Rather, the
study is used to make the claim that *if* erosion had wiped out the
record of the alleged ancestor's (_P. con.'s_) earlier existence,
then a false impression would be created that _P. con_ was not old
enough to be the ancestor of _P. chris_. This would only be true,
of course, if the evidence of _P. con's_ prior existence was
eliminated from *every locale*, not simply the locale in which it
allegedly gave birth to _P. chris_. If that occurred, it would
indeed be bad luck for the evolutionist because he could not use
the fossil record to argue that _P. con_ was the ancestor of _P.
chris_. <<
Nothing of the kind was in the Nehms and Geary article. All of that was my
argument against what you were advocating i.e. the idea that everything must
appear in proper order.. Go re-read what I said.
glenn