Joined: Sep. 2007
|Quote (Alan Fox @ Sep. 27 2007,11:25)|
|If you recall, this thread was originally intended for you to show how the evolution of the horse is a problem for the current theory of evolution. I have not seen a great deal of evidence from you, yet.|
In order to keep this thread on topic, I will try to keep my posts focused on the work of Schindewolf and Berg and (at least in the case of Schindewolf) also on the evolution of the horse.
Berg doesn't say a lot about horses other than this from section IV, "Convergence":
Nomogenesis, pg. 212.
|"At the very time when in North America the Equidae were being evolved, forms of the order Litopterna were being elaborated in South America in the plains of the Argentine. The latter are extinct ungulates, in many respects recalling horses: they had also lost the lateral digits of their limbs, and for progression made use of the median digit; their extremities and neck were likewise lengthened, and in the former, the ball-and-socket joints, by which movements in all directions could be accomplished, were being gradually supplanted by pulley joints, which restricted their limbs to being moved only backwards and forwards; their teeth lengthened and grew more complex (although no cement was present). This group was extinct in South America before the arrival of horses. The Litopterna, or pseudo-horses, thus copied the horses in many ways.|
The same course (as to limbs and teeth) as in horses was followed in the evolution of camels in the New World, and of deer, antelopes, sheep and oxen in the Old"
As for Schindewolf's position, why don't I just start by using the same quote I provided for you over at Brainstorms:
Basic Questions in Paleontology pp. 358-359, (emphasis his)
|To this extent,the one toed horse must be regarded as the ideal running animal of the plains. It's early Tertiary ancestors had four digits on the front feet and three on the hind feet, and low crowned cheek teeth. Since in the later Tertiary, an expansion of plains at the expense of forests has been observed, this change in environmental conditions and the consequent change in the mode of life has been represented as the cause of linear, progressive selection leading up to the modern horse.|
However, in the formulation of this view, not enough consideration has been given to the fact that the evolutionary trend of reduction in the number of toes had already been introduced long before the plains were occupied in the early Tertiary by the precursors of the horse; these inhabited dense scrub, meaning that they lived in an environment where the reduction of the primitive five-toed protoungulate foot was not an advantage at all. In the descendants, then, the rest of the lateral toes degenerated and the teeth grew longer step by step... regardless of the mode of life, which... fluctuated repeatedly, with habitats switching around among forests, savannas, shrubby plains, tundra, and so on.
If selection alone were decisive in this specialization trend, we would have to ascribe to it a completely incomprehensible purposefulness...
Both of these men intently studied real examples from nature and the fossil record and came to the same conclusions:
1. That evolution of types happened suddenly - not gradually.
2. That subsequent evolution proceeded as if constrained by laws.
3. That natural selection had nothing to do with the formation of any organ.
"If we all worked on the assumption that what is accepted as true is really true, there would be little hope of advance." Orville Wright
"The presence or absence of a creative super-intelligence is unequivocally a scientific question." Richard Dawkins