Directions : In the following question more than one of the answers given may be correct. Select the correct answer and mark it according to the code:
Which of the following statements are correct? (1) Dicondylic skull is charactersitic of all anamniotes (2) The jaw of placental mammal is formed by a single bone called dentary (3) Sweat glands are absent in Cetacea and Sirenict (4) The horn of Indian Rhinoceros is formed by gluing of epidermal keratin fibresA) 1, 2 and 3 are correct
B) 1 and 2 are correct
C) 2 and 4 are correct
D) 1 and 3 are correct
Correct Answer: A
Solution :
Dicondylic skull is found in frog and anamniotes. Since eye orbits are merely skin depression and the cranial skeleton lies completely between these, frog's skull is called platybasic. The two condyles articulate the skull with vertebral column. Thus, frog's skull is dicondylic skull. Sweat glands are absent in Cetacea and Sirenia as they are marine aquatic and there is no need of sweating.
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