Robert Broom's thesis is that evolution is finished. Even though his claims are more than 50 years old his observation seems to be well supported by evidence nowadays. It is no way easy to find his antidarwinian thoughts on internet, but something can be found in John Davison's Evolutionary Manifesto - especially the one about evolution of mammalian Orders from 1951:
In Eocene times -- say between 50,000,000 and 30,000,000 years ago --small primitive mammals rather suddenly gave rise to over a dozen very different Orders -- hoofed animals, odd-toed and even-toed, elephants, carnivores, whales, rodents, bats and monkeys. And after this there were no more Orders of mammals ever evolved. There were great varieties of evolution in the Orders that had appeared, but strangely enough Nature seemed incapable of forming any more new Orders.
But it's only a chart. One of the best preserved location when the phenomenon can be observed is John Day Fossil Beds National Monument. These fossil beds contain a rare continuum of 50 million years of plant and animal history, compared with 2 million or 3 million years at better-known fossil beds.
Even if we accept darwinistic claim that mammalian Orders are only naming convention we can neverthenless see that greatest diversification of mammalian Families and even Genera(!) occurs:
The periodof 39 to 20 million years ago (John Day Forma-tion) seems to harbor the greatest diversity inknown fossils of families and genera. Current diversity of families and genera of the basin assess-ment area does not match that of this period...
And last but not at least some ad hoc quotation from internet:
The great diversity of Holarctic primates during the Eocene indicates that at least 90% of modern diversity would already have been reached by the Middle Eocene."
A number of mammal orders show peaks of family diversity around the Eocene-Oligocene boundary, such as Soricomorpha, Rodentia, Primates, Artiodactyla and Proboscidea.
Perissodactyls were once much more diverse... Only seventeen species of perissodactyls remain on the Earth today, a shadow of the group's former glory.
So I see Broom's observation that "evolutionary clock has so completely run down" as the well supported claim nowadays too. Interpretation of the fact that no new mammalian Order aroused during huge time period from Eocene and that mammalian diversity generally seems to be fading instead suggests some "predetermined internal factors" behind evolution and no RM and NS as darwinists suppose.
Broom's evolutionary theory is based on the existence of some sort of 'intelligent spiritual agency' of two types: a) the lower agency, present in animals and plants, of limited vision and limited power, and b) that of a much higher type which has planned and directed evolution (via directing from time to time the former, inferior agencies). Broom pointed to the presence of an uncountable multitude of convergences which cannot be explained satisfactorily by lamarckism or by darwinism. Broom announced that evolution is practically finished, that the physical evolution has stopped but the process continues on a higher, spiritual plane.
The main argument you have presented is that mass extinction during K/T period emptied different niches which the surviving species filled during radiative adaption. Natural selection then intensified, preserving the best adapted. Yet the Eocene period gave rise not only to known land's mammals but also to bats and whales and sirenians. It would mean that there were empty niches not only on the ground but in the air and in the sea as well. Sirenians and whales belong to different mammalian orders, so mammals entered the sea twice independently. It would mean that in the sea there were more convinient niches as in the land for whales/sirenians predecessors. Oddly enough indigenous sea animals did not filled these emptied niches by radiative adaptation but mammals from land overtook them.
This should have happened during Eocene period where there was no strong selective pressure on the land as you claimed. Yet after then selective pressure intensified which led many mammalian orders, families and genera to extinction. Yet after Eocene there was no other succesfull attempt to enter the sea and air. Why? Supposing strong selective pressure on the ground we have to suppose the same - or stronger - selective pressure in the sea and in the air that hinder mammals to reenter it again. Due to strong selective pressure even Pinnipedia did not manage entered the water completely and freezed in their half-state.
On the other hand your theory mean that natural selection seems to be an antievolutionary force that tend to preserve pre-existing species already fully developed. It eliminates, destroy all novelties. So natural selection itself has not much to do with evolutionary progress. Where it is in effect it does not support and care for new solutions. It is not creative force. It just removes extremities - and this is literally in accordance with antidarwinian thinkers like Punnett, Grasse, Heikertinger, Davison.
Might be we should agree with a little bit changed Brooms sentence?
There were great varieties of evolution in the Orders that had appeared, but strangely enough Natural selection seemed incapable of forming any more new Orders.
Broom believed that evolution is directed by spiritual forces. I don't see connection with Lamarck's thesis that organism can pass on characteristics it acquired during its lifetime to its offspring.
There were probably many empty niches in the oceans -- I believe that the KT-extinction hit marine life harder than land life, but I'm not sure.
And might be there were no vacant niches in the oceans at all. Yet land mammals pushed back all species from their "local maximums" there. Might be that on the land there were much more emtied niches as in the ocean at that time and yet the evolution was driven in some cases by internal forces to the sea whatever it cost.
I bet that in examining the fossil record one would see an increase in new orders in all surviving classes at this time, including among fish, crabs, and whatever.
Anyway I have never heard about adaptive radiation of water species during the period discussed. The greatest adaptive radiation in the ocean I know about occured during cambrian explosion. So preliminary I would not bet a nickel on it.
Those better adapted to a more purely aquatic life would not fare as well as the present pinnipeds, those better adapted to a more tererrestrial environment would not do any better either.
How do you know? Maybe they would.
Maybe the niches were already filled. There was no more room for new entrants.
And maybe not. Maybe just evolutionary potentiality of Pinnipedia became exhausted.
My guess is that after human race has run its course, the end result of the mass extinction which we have produced will be that the relatively few remaining species will again undergo radiative adaptation, and we would (if we were around to observe it) the rise of many more new orders.
And my guess is the opposite one. There will be no adaptive radiation of mammals anymore (like there was no other saurians radiation after K/T). My guess is what we would find is what we already know just now. I guess we will see no changes (except thick and color of the fur of rats.) No way we would see any new species or even families.
You mentioned Pakicetus (PAKistan CETacean - yet might be this animal from Artiodactyla Order could't swim at all) . How it happened that mammals Pakicetus and Ambulocetus overcame sharks and crocodiles that survived K/T Yucatan meteorite impact very well? Subsequnetly fully adapted sharks and crocodiles were not so apt to occupy "emptied niches" of shallow warm waters of shores?
------------------ And last but not at least I would like to add John Davison's statement:
"Niches never had anything to do with it anyway. The whole thing was planned form beginning to end just as Broom claimed." -----------------
Dinosaurs disappeared at the boundary between the Cretaceous and Tertiary periods. Based on fossil evidence, the crocodiles showed no change in diversity or distribution across this K/T boundary.
There was no response to this thread at least for 5 days. Why do you post your response just few minutes after my post? Is it common tactic of darwinists to stifle unpleasant facts and to stray the discussion away? Using weird thoughts that have nothing to do with the main topic that my previous post adressed?
Iceage posted almost 2 hours after you did and was not responding to you or the member you were replying to.
I would say the thread was dormant 5 days. I edited my post at 01:08 today.
Edited by MartinV, 02-16-2007 01:08 PM: No reason given
Member "iceage" responded 17 minutes later (01:25). Out off topic I would say. The topic is End of mammalian evolution. I strictly keep the line. I am waiting for neo-darwinistic response and no for spam.
The K-T event devastaed shallow water marine ecosystems. The ammonites, huge predatory cephalopds (coiled shells 3 meters across) were extremely widespread and diverse. These probably had a top-down control on prey items (IOW Cretaceous bad time to start evolving from terrestrial to aquatic). Belemites, another group of cephalopods were also extinct after this event. Rudists were very large bivalves (not closely related to any living bivalves) that formed massive reefs in Cretaceous seas and kilo for kilo probably accounted for most of the aquatic biomass in shallow seas. Completely absent after the Creataceous.
Yet sharks seems to thrive as well as once. For instance:
The most recent elasmobranch radiation coincided with the mammalian radiation which eventually produced ourselves. Modern elasmobranchs are thus the distilation of millions of years of experiments in How to Build a Predator.
Some types of sharks became even non-predatory animals - Basking shark, White shark. So I would say there were not enough "emptied niches" for all predatory sharks. It is curious that having such sharks variety there was neverthenless enough space left for land mammals to enter there and to feed themselves like pre-adapted sharks that had already occupied the niches .
The group including modern marine crocodiles are not known until the Tertiary so your statement in another post about no change in crocodile diversity is, well, a crock (just an aside, and maybe this was an error, but you might want to avoid citing undergraduate web projects as primary sources. Especially when those sources do not contain the info you claim anyhow).
Anyway crocks survived K/T as well as birds did. Arent birds and crocks close relatives btw? Crocodiles (salt-water) look like Ambulocetus - but somehow there was no selective drive into the sea.
And it seems also that there was in the air enough space and niches for mammalian bats to enter it - yet it is hard to believee that birds could not find these niches or accomodate to them before bats evolved.
So relatives of crocodiles - birds responded to opportunity and filled "emptied niches" in the environment. Ambulocetus that seems lived in the same environment as crocodiles responsed to opportunity and entered the sea. Crocodiles somehow did not react to changing environment at all - yet it may be of interest that before K/T crocodiles reacted to such challenge in the form of marine Geosaurs. The same may be generally applied to reptiles that survived K/T boundary.
So whether due to Yucatan meteorite impact or not, there were many different reptiles and non-mammalian animals that survived K/T boundary. Yet they were unable to "respond to new opportunity" and to fill "emptied niches" as succesfully as mammals did. If there was not impact of the meteorite I would say (using darwinistic theory) that mammals would overpower reptiles anyway. It would had taken more time, but the observed "responses to opportunity" seems to work in favour om mammals and theirs greatest outcome - mankind.
There is also the issue of warm-blooded versus cold-blooded and both being air breathers -- this would have limited the crocodile ability to dive in deep water and actively pursue prey compared to a warm-blooded competitor (or a cold-blooded water breather). This would limit the ability of crocodilians to become like whales. Evidence for this is also in the areas where crocodiles live -- only where there is warm and relatively shallow water.
Yet according Nature 2005 crocodiles have warm-blooded ancestors.
It seems that these cold-blooded creatures, with their limited capacity for prolonged activity, might have had active, warm-blooded ancestors.
In the quote above Martin states clearly "The most recent elasmobranch radiation coincided with the mammalian radiation..." (bold mine). He is talking about what occured after the event which destroyed nearly all shallow water and terrestrial species over 50 kg.
He also states that marine extinction hit only 15% of marine invertebrate families. Even if we assume that 90% of species died out the diversity of invertebrate families reminded pretty well preserved due to fact that 85% families survived. Might be that the same numbers are applicable to other marine families, I don't know.
Yet sharks survived K/T boundary as well as crocodiles did. The salt-water crocodiles distributed in Asia nowadays are well adapted for hunting in estuaries. So combining predators sharks and crocodiles I don't see how Pakiceus in Pakistan managed avoid these well-adapted pre K/T predators and entered the sea neverethenless - and even share with them same niches obviously. I personally fail to see there "emptied niches".
It is also interesting that according some latest conceptions there were not only warm-blooded crocodiles but also dinos. Yet they didn't survived K/T boundary. What seems to had been once advantage for mammals seems to be disatvantage for crocs and dinos in the same area at the same time. Yet cold-blooded reptilians survived K/T boundary mostly unaffected and neverthenless they were unable to fill "emtied niches" as succesfully as mammals did.
The evolution of 'filter feeding' (btw, I hate that term. In my classes it is known as the "F-word" because I take off points when I see it used on a paper) has absolutely nothing to do with a lack of emptied niches. It makes no more sense than to say whales evolved to swim because all of the walking niches were filled.
Than behind evolution are other forces than darwinistic "struggle for survival" or random mutations, the best of which are picked by Natural selection to fill "emptied niches". If a bear had creeks full of salmons all the year than there wouldn't be need for them to became a whale I suppose.
Suspension feeding (<-- used instead of the F-word) typically evolves as predators specialize in capturing small but abundant prey.
If there is abundance of great prey I do not see reason why to transform to small-prey eater. Only if the predator somehow foresee in advance that environment could change... That means if the species possess some kind of "spirit" and is not formed by blind adaption to existing environment.
Why did Pakicetus evolve toward an aquatic environment? Well, evidently some Pakicetus had a mutation that allowed a more efficient use of a more aquatic environment, and these Pakicetus were able to thrive. Just like the pachinko ball, that is pretty much all we can say.
Pachinko ball doesn't have predators hunting it like crocs and sharks. Try game again using pachinko ball made of meat in the pool overcrowded with crocks or sharks.
Huh? You mean the subsequent evolutionary history of life was already written in the first cell three and a half billion years ago? How does that work?
Problem is difficult. According some popular medieval conceptions (Giordano Bruno was it's follower) matter possesed spirit once. Might be that spirit is going upwards and is now fully presented in humans. The spirit presented himself and his creativity in mammals during "adaptive radiation" during Eocene and before during "Cambrian evolution" in lowest phyla. That's why evolution of mammals is finished. Species do not possess as much spirit as once. At least -according Chardin - we see during evolution increasing perfection of nervous system. Just an idea.
Those that were deep sea predators or warm-blooded predators were killed in the mass extinction, leaving those niches open for later animals to take the opportunities available.
Warm-blooded predators were superseded by other warm-blooded mammalian predators and cold-blooded reptilian predators. What was the disatvatage of this warm-blooded predators to be replaced by another ones (it is claimed by darwinists that warm-blooded feature was one of the reason of succesfull mammalian radiation during Eocene)?
I suggest you try to make it to the Mediterranean on your next vacation. Even if you are too scared to go into the water yourself, go to the beach anyway just to watch the people. You will see lots of people playing in the water without being eaten by crocodiles and sharks.
And perhaps you should try your next vacation somewhere at forgotten India's tidal estuaries or marine swamps. Don't bother yourself nobody except you is entering the water to swim and relax there.
It was Thewissen not me who claimed that Pakicetus evolved in such an environment (and ambulocetus possessed even crocodile-like head!). As you know during Eocene the climate was much more warmer than today - ideal condition for crocodiles I would say. And it were you darwinists and not me who claimed that there were emptied niches after K/T that mammals filled. Might be crocodiles were gentlemen at that time and did not filled their own niches in order to enable enough time for hoofed Artiodactyla Pakicetus to became crocodile-like Ambulocetus in shallow water.
But there is that magical spirit that not only forced mammals to evolve, but it also protected them from crocodiles and sharks.
I have given you only some idea. Might be that macroevolution represented by Davison's Manifesto is the better explanation. Species aroused via saltationism - then they are adapted to the environment fully and can compete with those that have been already there. And we don't need anymore darwinistic fairy-tales about emptied niches.
Yet cold-blooded reptiles could survive quite well. It seems like warm-bloodeness was disatvantage during K/T boundary - but only for dinos. For mammals it was somehow advantageous.
That is radiation to fill available niches AFTER the K/T event. There were no animals in those niches then, so they were up for grabs by whatever came along that could take advantage of the opportunity.
We don't know if niches were really so empty.
Warm blooded just means that they have higher levels of energy available, whether they were reptiles, birds or mammals. That higher energy translates to increased fitness.
In the warm climate of Eocene I do not see the advantage. Cold-blooded reptiles thrive in the warm areas quite well even today.
Problem is the fact that let say last 30.000.000 years no mammalian Order aroused - and families declined. No doubt there were great extinctions also after K/T boundary which concerns mammals - even if not so spectacular. Wheter we believe Raup or not. Also major Europe-wide mammalian faunal turnover termed the Grande Coupure occurs during Eocene-Oligocene boundary. There were glacial periods too. None of these events created enough "niches" for any interesting development of mammals. I also discussed above that there were probably no "emptied" niches for mammals to enter the sea while crocodiles survived K/T boundaries and probably occupied niches that mammal Ambulocetus (looked like crokodile too btw) had to enter into as "unoccupied".
It all seems like play with magic formula "empty niche". Stasis? - there were no "empty niches". Radiation? - there were lot of "empty niches". That stasis and fast evolution occurs together hand in hand on the same area at the same time concerns nobody.