Egg proteins are necessary for an embryonic development
Complex organisms need cells that can perform many different functions. they need to be supported on a cellular level. Without specialized cells you they won't be able to perform different functions.
Allopatric<span> speciation occurs when new species arise as a result of geographic isolation from the ancestral species. It involves an extrinsic barrier to gene exchange and can occur by a number of means including subdivision or peripheral division.</span>
Answer:
An index fossil is also known as guide fossils or indicator fossil. They are fossils used to determine and identify geologic periods.
The main characteristics of an index fossil include :
1.It must be distinctive.
2.It must be widespread.
3. It must be abundant
4. It must be limited in geologic time.
Due to trends and studies of most fossil-bearing rocks being formed in the ocean, the major index fossils are mostly marine animal or plant organisms.
