Bats developed a reproductive scheme that involved flying, eating insects and hiding in caves during the day that did not involve insurmountable competition from any other species and was adequate for their survival.
After 10 minutes of googling:
Previous studies suggest that many species of insectivorous bats are nocturnal, despite the relatively low availability of their insect prey at night, because of the risk of predation by diurnal predatory birds. . . . In contrast, northern bats (Eptesicus nilssonii), fed mostly between 22:00 and 02:00, coinciding with the lowest aerial insect availability, and with the period when light levels were lowest (ca 1000 lux). Bat activity patterns were closest to those predicted by the avian competition hypothesis. . . . Possibly populations of both species were higher historically and the observed patterns reflected historical competition.
Disappearance of old forests goes together with disappearing of roosts of forestdwelling bats. Furthermore, deficiency of roosting possibilities is worsened by the fact that competition between birds and bats may increase while numbers of tree holes decrease (Mason et al. 1972).
The fact that completely non-aquatic deer can drink out of a river without being eaten to extinction, the fact that manatees can live in swamps without being eaten to extinction, and so forth shows that prey animals can coexist in the same environment as predators. In fact, if they couldn't the predators themselves would become extinct. So I see no reason why the transitional forms between, say, pakicetus and modern whales couldn't coexist with crocodiles and sharks; other animals manage to do it.
When they could coexist with Ambulocetus very well in a given niche once why we don't observe evolution of land mammals into aquatic ones after Eocene any more? It was your explanation that mammalian radiation occured because of "emptied niches". If niche could be filled and evolution occured what impeded fishes to go out from water and what impeded land mammals became aquatic animals after Eocene? Evolution should continue with the same pace - if filled niche did not influence evolutionary process during Eocene there is not reason why it should influence it afterwards.
I'm not sure why you think that crocodiles should have grabbed up all the good niches (uh-oh, there's that word again) before ambulocetus had a chance to evolve into them.
They had let say 5.000.000 years to found out all good niches on the shore. But again - after ambulocetus evolved - there were not anymore "emptied niches" afterwards available for evolution of land mammals into aquatic ones during next 30.000.000 years (except Pinnipedia)?
Perhaps the early whales survived and thrived because they were hunting rather than being the hunted.
My point is that they entered environment with fully adapted predators and yet there was enough space and nurture for them too. If the nurture is really no problem as you seems to admit with your "shopping store" story I see no selective pressure in the Nature at all. All development subsequently was a matter of "internal factors" .
The term â€œnicheâ€ has no effect on the processes involved in evolution. It is a convenient word to use to denote differing survival strategies. Do not let the word constrain your seeing the grander picture.
I have just challenged these darwinistic "niche", "natural selection", "survival strategies" words in order to see grander picture without distortion.
A young ambulocetus entered the Ocean during Eocene. The Ocean was full of predators at that time. The Ambulocetus was predator too. The father Ocean is always full of foods and delicate meals for all predators. In the Ocean there it's like in the shopping mall. Whenever you came it's open. There's a lot of items to choose. Just enter, please. Father Ocean is waiting for you 24/7/365/Eons to become a predator. Other predators are looking forward to meet you.
Was? It still is. The KT-event emptied a lot of niches.
So your reasoning returned back to "empty niche" explanation in this case of whale origin. Never mind, the same can be found at talkorigin:
Before the late-Cretaceous extinctions, the Mesozoic marine reptiles such as the plesiosaurs, ichthyosaurs, mosasaurs, and marine crocodiles might well have feasted upon any mammal that strayed off shore in search of food. Once those predators were gone, the evolution quickly produced mammals, including whales, that were as at home in the seas as they once were on land.
It's really a big misunderestanding that crocodiles "were gone". It's on you which of plesiosaurs, ichthyosaurs, mosasaurs hunted in estuaries - anyway crocs survived and according darwinism should be able to fill emptied niches geometrically. According Talkorigin crocodiles were present with Pakicetus:
Although the mammalian fauna found with Pakicetus consists of rodents, bats, various artiodactyls, perissodactyls and probiscideans, and even a primate (Gingerich and others 1983), there are also aquatic animals such as snails, fish, turtles and crocodilians.
I would say that conception of "empty niche" that Pakicetus filled is more than questionable.
Using the same logic we should explain the stop of transition of other mammals into aquatic species after Eocene like:
"After Eocene marine mammals like dolphins, whales and marine crocodiles might well have feasted upon any mammal that strayed off shore in search of food." Eh,eh.
At every stage of their development from land to water the whale ancestors were fully adapted to the environment they were in.
Might be the more you repeat it the more you are convinced it to be true.
Yet when all of them from Pakicetus, Ambulocetus etc.. were so "fully adapted" why all of them disappeared? Ambulocetus looks like crocodile - why we don't find him today? All ambulocetuses transformed into whales? (And crocodiles refused to transform in the same niche at all?) Ambulocetus evolved into whale and crocodiles remain in the same niche unaltered?
No other branch from Pakicetus has evolved that survived till today? Is it possible that on the cladogram nothing except whales live nowadays (exceopt fully marine mammals)? Is there really no living branch on the cladogram of land-whale transiton when all of them were so fully adapted? Crocodiles were also fully adapted and are fully adapted even today I suppose.
However, Davison's claim is that no new genera have evolved since then.
Obviously you didn't read Davison tretase at all. Anyway Lang supports Broom's idea that evolution of genera and species stagnates in quartenary too:
At the end of the Tertiary the organisms consisted of species, almost all of which can be assigned to present genera, a large section even to living species. This applies not only for the European flora but also for its fauna.
"Despite the environmental conditions for this time period have been characterized as excessively varying, temperatures rising and falling producing among other effects a series of ice ages â€“ and in spite of all these environmental variations there was hardly any evolution at all."
You also haven't explained why you find the conception of a vaguely defined, unobservable "spirit force" to be reasonable.
I agree with the idea of Robert Broom. Might be it is not reasonable but I don't force you to agree with it. You have your random mutation, natural selection, empty niches.
â€¦the strange course of the history of life on the earth appears to admit of but one explanation â€“ that it has been brought about by spiritual agencies and that the production of man has been the chief purpose of it all. Though man as we see him to-day may be regarded as a very disappointing result of all these millions of years of evolution, we must not consider human evolution quite finished. Physically man may change very little in the next 10,000,000 years, but mentally and morally it seems possible he may evolve almost into a new being.
And some have mysteriously "disappeared" ... because they have been reclassified into other existing taxons.
They didn't disappeared. As our knowledge increase we reclassify some organisms. We know more on relationiships between different organisms. Statement that higher classification doesn't exist as such is curious one - I suppose only darwinists use such a notion of "classification". Classification is no way some human invention, it exists and many branches of science - not darwinism of course - do not doubt it. Chemistry knows "acids", "proteins", "alcohol" etc (Even DNA and RNA could be considerred as classification). No one consider these classification to be something artificial. No one claim that only "chemical components" exists and all rules above them that classify chemical compouds are arbitrary. No one doubt about proteins or RNA to be something "arbitrary".
So there is no reason to doubt that wolfs, giraffes, beasts(carnivora), rodents and whales exist in order only to support darwinistic gradualism.
Given this grayness and randomness in the course of biological evolution here on Earth, I have to conclude that the evolution of human consciousness was manifestly too gray and too lucky to have occurred anywhere else in the universe.
The evolution of human was inevitable - all previous evolution served only as a mean to this outcome. Luck and chance has nothing to do with it. As John Davison observed in his Manifesto - the course of phylogeny might be as inevitable as course of ontogeny.
It was an amazingly empty world, not only in terms of biodiversity, but in terms of sheer numbers of individuals. Picture a closet stuffed with clothes. Remove 75% of them. Lots of room for new articles, n'est-ce pas?
It depends what exactly you remove. If you remove 75% animals from each species I would say nothing happens - remaining individuals will geometrically fill niches. According previous information 85% of marine Orders survived K/T. So diversification of life remain partly unaffected after K/T in the Ocean.
Why didn't the existing surviving aquatic predators match the "explosive" radiation of the terrestrial mammals - to the point that nothing else could play in their sandbox?
That's the question. Why crocodiles and sharks didn't occupy emptied niches? Why after Ambulocetus left estuaries no other mammals entered it again?
It's not only the problem of the land-sea transition of mammals. Eocene lavish on curious mammalian forms. One should suppose much more niches at that time as nowadays. Neverthenless climate was warmer so why we didn't observe in reptiles realm "adaptive radiation" too? While Pakicetus became through Ambulocetus fully marine whale, crocodiles seems to be in stasis (occupying the same niche as Ambulocetus).
One should really take into concideration possibility that something like "internal factors" hindern reptiles evolve after K/T period even though niches were emptied for them too.
Classifications are useful for discussions, but the world\universe does not rely on them for the existence or behavior of life.
Of course they exist. Even animals recognise them in order to mate themselves, to recognise what to hunt and what to avoid. It's a weird opinion that cats learn to avoid german shepard, bulterier, canis lupus etc and that they do not make some generalization of canidae family. It's a matter of survival to make such classification for them I would say (no-verbal classification of course).
Generalization (to decept other, to pretend to be a member of different group of classification) is even darwinistic explanation of allegedly effectiveness of mimicry.
What is not arbitrary is the hierarchy of relationships based on common ancestor populations, but every classification before and after speciation branches is totally arbitrary on where the lines are drawn.
Because common ancestor does not exist only darwinistic classification is arbitrary. All the others classifications tend to describe animal reality finding out "substance" "essence" of animal diversity and unity via classification. Like in chemistry - they also do not classify chemicals how they evolved but what they really are, what characteristics they have.