Explanation:
Index fossils are fossils type fossils that are used to identify stratigraphic records and their positions. They are vey key in determining relative ages of rock sequences.
- These fossils have a short vertical stratigraphic range.
- Index fossils have short evolutionary history.
- They are widely distributed in nature.
- Examples of index fossils are trilobites and ammonites.
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Answer:
Monotremes, marsupials, and placentals are the three animals that could match this phylogenetic tree.
Explanation:
Monotremes, marsupials, and placentals belong from a common ancestor. Those organisms which have one common ancestor are also called monophyletic. These animals have some changes which occurs with the passage of time but most of characters are similar to each other. In placentals animals placenta is present while in Monotremes and marsupials this placenta is absent.
Each ear should have vestibular apparatus which consist of saccule, utricle and three semicircular canals. The organ can detect horizontal acceleration, vertical acceleration, and rotational acceleration. Impaired vestibular apparatus will result in losing the sense of balance.
The organ is very sensitive as it was able to detect a small acceleration. That is why most disease in the vestibular apparatus will result in an acute(fast onset) fake perception of acceleration, called vertigo.