Robert Carroll on whales and mesonychids

[Bpelta]

Okay, so excuse my scientific ignorance, horrible education.

Chalk it up to masochistic tendencies, but I’m in the habit of reading a creationist blog. I just read the following quote over there:

Robert Carroll, a highly regarded evolutionist and an expert in vertebrate paleontology, admits as follows: “It is not possible to identify a sequence of mesonychids leading directly to whales.” (Robert L. Carroll, Patterns and Processes of Vertebrate Evolution, Cambridge University Press, 1998, p. 329.)

Okay, so I look up the source and a few lines later, Carroll writes as follows:

The transition between mesonychids and primitive but obligatorily aquatic whales is represented by a sequence of intermediate animals from the upper portion of the lower Eocene and the lower half of the middle Eocene of Pakistan, continuing into the later middle and upper Eocene of Egypt and southeastern United States (Fig. 12.20). This sequence extends over a period of 10-12 million years, beginning with riverine sediments, including primarily fossils of terrestrial mammals, through shallow coastal marine, to deep neritic deposits at the edge of the continental shelf. Several genera are recognized, showing the progressive reduction in the size of the appendicular skeleton, freeing the tail for aquatic locomotion, and a succession of modifications in the structure of the middle ear.

So what’s he saying here? The first line quoted makes it sound like we don’t have a direct lead in the fossil record from mesonychids to whales. The paragraph quoted makes it sound like we do.

(You can see the context of the Carroll quotes inside by clicking here and then searching for “sequence of mesonychids”.)

[Phlosphr]

It means there has been no missing link found of the exact animal - but we have data [fossils] that show similar animals that may have been related to that missing link 10-12 million years ago.

[Sailboat]

Dunno about Carroll but Gould seemed to be persuaded.

[Polycarp]

@Phlosphr

It means there has been no missing link found of the exact animal - but we have data [fossils] that show similar animals that may have been related to that missing link 10-12 million years ago.

Not 10-12 million years ago (which would be during the later Miocene) but over a 10-12 million year span during the later part of the Eocene, which lasted from 56 to 34 million years ago – say from 48-47 to 37-36 MYA for the mesonychid-to-whale evolutionary sequence.

Comparative DNA analysis shows that the whales are firmly within the “cetoartiodactyl” clade, falling somewhere between pigs and hippos on the one hand, and camels and ruminants (deer, sheep, cattle, antelopes, etc.) on the other. However, this is not a bar to the fossil-evidence descent from the mesonychids, as they wsere “hooved meat-eaters” which have left no living descendants other than the whales, so they could very well fit into the same clade. (Prior to the whale-ancestor hypothesis, they were sort of an orphaned clade which didn’t really fit well into any of the fossil-mammal orders.)

[Chronos]

We don’t have direct evolutionary links for pretty much anything. What we do have is “this fossil appears to be closely related to an ancestor of X”.