What are some examples of index fossils

Ammonites, , Brachiopod, Grapolithina, Trilobites and Nanofossils are examples of index fossils

Explanation:

Ammonites were common during the Mesozoic Era (245 to 65 mya), but were not found after the Cretaceous period. They went extinct during the K-T extinction (65 mya)

Brachiopods which are mollusk-like marine animals appeared during the Cambrian (540 to 500 mya). Some types of them still survive

Grapolithina which are widespread colonial marine hemichordates that also lived during the Cambrian period.

Nanofossils are microscopic fossils which are remains of calcareous nannoplankton, coccolithophores from various eras

Trilobites were common during the Paleozoic Era (540 to 245 mya); about half of the Paleozoic fossils are Trilobites. Trilobites evolved at the beginning of the Paleozoic Era and went extinct somewhere in the late Permian period which was 248 million years ago

This might be extra information but i hope it helps

regulation of gene expression. gene expression can be regulated by various cellular processes with the aim to control the amount and nature of the expressed genes. these regulatory proteins bind to dna and send signals that indirectly control the rate of gene expression

explanation:

answer: tributaries flow into rivers.

wetland is a biome that develops when the water gets accumulated in a land exhibiting a huge depression. these form either seasonally or permanently. the water in the wetland comes from rivers, lakes, ocean, flood, rain or other sources. the wetlands includes mangroves, marshes and peatland.

tributaries flow into the rivers develops a wetland because such water will get deposited in the depression and will restrict the original flow of tributary water. hence, water with low drainage current combines with the river water.