Baraoia
No your making excuses for why you can't use the fossil record to show just one line of a creature that became importantly another line. if there are no fossils, patchy record, then you have no evidence on this point of fossil evidence.
First of all, we have shown you more than one transitions in the fossil record. The problem isn't that we don't have them, it's that you don't accept that they represent time sequences. I think I'd better leave that for the geologists to explain, though the South African Karoo Basin and related formations (which I'm sure I mentioned to you recently) contain a good part of the reptile-mammal transition (and also, IIRC, some early dinosaur history) nicely layered. Less mammal-like creatures (for example, gorgonopsids) appear lower down in the series than more mammal-like ones (cynodonts). [But see below for more...]
I have also said that the fossil record is amazingly strong evidence for evolution despite the extremely long odds against most creatures ever fossilising. I have not used the patchiness of the record as an excuse for the lack of evidence, I used it as an explanation of why only
some
transitions have fossil evidence. As far as I can tell, there's nothing I've brought up in that explanation that isn't true. And if the points I brought up about fossilisation are right then the imperfection of the fossil record is a logical consequence.
Once again, if you think I'm wrong then
counter my points, don't just
say I'm wrong.
Above the k-t line rock creation would be from quick local events in a post flood world. I suspect a general earth action about 400 years or so after the flood for other reasons.
Right, you "suspect".
Would you mind detailing your "other reasons"? Or in fact what that "general earth action" was?
The whales did not exist during the flood but only moved to the sea after the flood and fossilized in the action I mentioned.
In the action you
alluded to, to be more precise.
AGAIN it is your turn at bat. Its your sides chance here to show and shut up creationists by showing a single mine of transitions from point a-b. Not pinpricks but actual list of fossils showing body change from a-b.
I say you can't do it.
Once again, I can, but you have to detach yourself from your flood nonsense first...
*cries out for help to the geology people*
Although, in the meantime let me give you the closest example to a "single mine" that I can think of.
Let's return to the mammal-like reptiles from the Karoo. Not quite from a "single mine" but close enough, come a large number of diverse species, which makes chronological trends easier to observe. (Unfortunately these guys and their geological environment seem badly neglected outside the technical literature, so it's hard work digging up pictures and good information
)
This (
Figure 1 from now on
) is a link to a series of drawings of skulls and jaws that all belong to fossil mammal-like reptiles.
Out of these animals, I think,
Pristerognathus,
Procynosuchus and
Thrinaxodon come from South Africa (in this chronological order, from Middle Permian to Early Triassic).
Pristerognathus is probably way off the direct line to mammals, so you can consider something that's closer to it - say, a gorgonopsid (an added benefit is that gorgonopsids are more primitive than any creature in Fig.1.). Many gorgonopsids were present in Middle to Late Permian South Africa, I'll pick
Lycaenops because I could find a half-decent
skull drawing of it on the net.
Probainognathus is South American but AFAIK it's similar (at a similar degree of mammal-likeness anyway) to South African
Pachygenelus/
Diarthrognathus; similar animals are Late Triassic to Early Jurassic.
Morganucodon also has a similar South African relative,
Megazostrodon. These creatures, which are either classified as true mammals or very close to true mammals, appear in the Early Jurassic (or perhaps the very latest Triassic, but I'm not sure about that)
IOW, you can take Figure 1 as a series of animals from the same place, in the same order as they are preserved (bottom, obviously, being oldest).
Some trends towards mammal-likeness include
- increased differentiation of the teeth - that is, molars and incisors that start out as typical simple, conical reptilian teeth acquire the shapes and cusps characteristic of mammals (although this isn't very obvious from Fig.1, as cynodonts, which all but Pristerognathus are, are already well advanced in this trend)
- enlargement of the dentary bone - which is the only bone in the lower jaw of mammals - and reduction of the other lower jaw bones. This should be fairly apparent in these examples. Also note the Lycaenops skull - although the picture isn't very good, you can probably see that the jaw bones other than the dentary (at the back of the jaw, labelled) are fairly large.
- enlargement of the coronoid process - this is the bit on the jaw labelled "cp" in Fig.1. IIRC it's an attachment site for jaw muscles in mammals. It's not visible in the Lycaenops picture, but as you can see in another gorgonopsid skull (Dixeya), it's fairly short and thin in gorgonopsids. Also, another "prong" forms in addition to the coronoid process (and I can't for the life of me remember the name of it) look especially at Probainognathus.
- enlargement of the temporal fenestra (and later fusion with the eye socket.) The temporal fenestra is the hole behind the eye socket. It makes the skull lighter and provides space for jaw muscle attachment. Again, it's a good idea to go back to gorgonopsids as cynodonts, which make up most of Fig.1 already tend to have large TFs; the ones in Lycaenops (or Dixeya, if I've already pasted that picture let's use it) are proportionally smaller. If you go back to even more primitive mammal-like reptiles it gets even smaller than that, but I don't think our "single mine" extends far enough back in the Permian to contain those.
- appearance of a new jaw joint - reptilian jaws (including gorgonopsids) form an articulation between one of the small bones at the back of the jaw and another bone in the skull. The single bone of the mammalian jaw articulates with a different skull bone. Many (all? Heck, I'm forgetting all I know about these guys!) cynodonts have both jaw joints, and the mammalian joint gets progressively more important as the tiny bones at the back of the jaw are marginalised (incidentally, they did not all disappear. They are now our hearing bones).
Things that cannot be seen in the skulls but also form trends up this kind of series include
- disappearance of lumbar ribs - this is thought to accompany the evolution of the diaphragm (which lets mammals run and breathe at the same time, something that your typical lizard can't do) and happens in cynodonts.
- development of a more erect stance - throughout the history of mammal-like reptiles. The hindlimbs become semi-erect and then upright first, followed by the forelimbs.
- development of a bony palate - reptiles' nostrils open into their mouths, which makes breathing while eating a bit difficult. Mammals have a bony shelf that separates the two cavities. The secondary palate, IIRC, becomes fully closed in advanced cynodonts.
These are
not animals purposefully picked to give the illusion of a trend. They are representative of
types of animals that inhabited the Karoo Basin from the Middle Permian to the Early Jurassic, and the groups, though overlapping, appear and disappear in the order they are in the transition.
I think it's
your turn now