Question

In Horse, the single large hoof represents
(A) Third digit
(B) First digit
(С) Fourth digit
(D) All the above

Answer 1

Paleontological study helps in understanding and locating coal and hydrocarbon sources. Palyno Fossils tiny microscopic spores, pollen and other vegetal remains of the past-assist us in interpreting ancient environmental conditions favourable for organic matter accumulation and Its Conversion to fossil fuels by transformation and subsequent thermal alteration.

Complete answer:
The evolution of the modern horse began in the Eocene epoch. The first fossil named Eohippus, 'dawn horse', was in North America. This horse was about The size of a fox or terrier dog (a type of small dog for unearthing foxes), only 40 cm high at the shoulders.
It had a short head and neck. The forelimbs were with four complete fingers (2, 3, 4 and 5) and one splínt of first finger and the hind limbs with three functional toes (2, 3 and 4) and one splint of fifth toe Splints are non-functional reduced fingers and toes of horse.
Teeth were with incomplete cement. Molar teeth had no serrations.
Now let us gather information about given options :-
(A) Third digit: the hoof of the horse is made up of third digit. This digit is extended and it bears all the weight. The horse has three to four toes that get converted into a single big digit and it helps the horse while walking and running.
(B) First digit: the first digit of the horse is just a toe and it is not so long. The forefeet of mesohippus has three fingers and one splint of the fifth finger and hind feet possess three toes. But the middle one is longer than others.
(С) Fourth digit: In Merychippus horse the fore and hind limbs had three fingers and three toes , the middle finger and toe being longer than others and supporting the entire weight but it did not function as hoof.

Our required is A. third digit.

Note:
During evolution of horse, there was:
General increase (with occasional decrease) in size, Progressive loss of toes, Lengthening of toes that was retained, Lengthening of limbs in general, Enlargement of brain, especially cerebral hemispheres, Increase in height, Increase in the complexity of molar teeth and an enlargement of the last three premolars until they came to resemble molars.