:: : Back to animals, for a second-- I did come across something very interesting recently while reading about the rhinarium, or mammal wet nose.
22.
"Paradoxurus " species have a broad head, a narrow muzzle with a large rhinarium that is deeply sulcate in the middle, and prominent angles above anteriorly.
23.
The surface of the rhinarium does not have any olfactory receptors, so it is not used for smell in terms of detecting diastema ) between the roots of the first two upper incisors.
24.
Lions, when compared to tigers, also have strongly retracted nasal bones, but a lion's rhinarium, or external nose, is no more retracted than the tiger's.
25.
In mammals that dig or root with their noses, the rhinarium often develops into a resilient pad, with the nostrils off to the side or below, and capable of closing for exclusion of dust.
26.
Apparently the groove on the rhinarium, the philtrum, is embryologically similar to the groove primates ( and humans ) have under their nose, even if they do not possess a wet nose ( i . e . haplorhines ).
27.
The strepsirrhine rhinarium can collect relatively non-volatile, fluid-based chemicals ( traditionally categorized as pheromones ) and transmit them to the vomeronasal organ ( VNO ), which is located below and in front of the nasal cavity, above the mouth.
28.
Furthermore, the size reduction of the upper incisors may create a gap between the teeth ( interincisal diastema ) that connects the philtrum ( a cleft in the middle of the wet nose, or rhinarium ) to the vomeronasal organ in the roof of the mouth.
29.
Typically the rhinarium is crenellated ( wrinkled or embossed ), which, as a generalisation has been speculated to increase its sensory area, but there are many exceptions and variations among different mammalian sensilla, so it is appropriate to treat generalisations with caution in this matter.
30.
Considerations that influenced the debate might have included the view that the Chrysochloridae are very primitive placentals and the fact that they have many mole-like specializations similar to specializations in marsupial moles . The rhinarium is a greatly enlarged, dry leathery pad that protects their nostrils while the animal digs.
