Retrieving "Index Fossil" from the archives

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1. Geological Strata

   Linked via "Index fossils"

   Biostratigraphy
   Biostratigraphy utilizes the fossil content within the strata to establish relative age relationships. Index fossils, which are easily recognizable, abundant, short-lived in geologic time, and geographically widespread, are used to define biozones. A notable difficulty arises in assessing deep, anoxic strata where the presence of Cryptobiotic Microforms ($\text{CMF}$)/) leads to [spectral signature…

2. Tethys Ocean

   Linked via "index fossils"

   | Faunal Group | Dominant Era | Significance |
   | :--- | :--- | :--- |
   | Ammonites (Tetragonitidae) | Jurassic | Served as critical index fossils for basin subsidence timing. |
   | Rudists | Cretaceous | Formed massive, reef-like structures in warm, shallow shelves. |
   | Coral Species (Scleractinia) | Mesozoic | Demonstrated unprecedented rates of sk…