An extinct species is a species of organisms which no longer exists on the planet or has ceased to exist. OR
An extinct species is a species that has completely disappeared from the planet i.e. a single living specimen of which, neither male nor female, exists on earth.
No more of a population.
(of a species, family, or other group of animals or plants) having no living members; no longer in existence.
extinct animals are animals that there are none left of such a the dinosour and the mammoth these animals are gone they are not alove all of them are gone.
Reproductive Isolation
It's not so much the organism or a type of organism that is difficult to define as a species but rather the differences in the theories regarding the definition of the word 'species'. For example the Biological species concept and phylogenetic species concept can be at odds when looking at convergent/parallel evolution.
A hominoid is any Primate of the group that includes humans (and our, extinct, ancestors) and the Great Apes.
It's not so much the organism or a type of organism that is difficult to define as a species but rather the differences in the theories regarding the definition of the word 'species'. For example the Biological species concept and phylogenetic species concept can be at odds when looking at convergent/parallel evolution.
An acid is a species which can accept an electron pair.
The effects of animal extinction are felt by the environment for years. All plants and animals of a particular ecosystem work together to keep things leveled out. When an animal becomes extinct, it affect the food web and how the remaining plants and animals depend on each other.
Because
define and compare the term species, population, and ecosystem
biodiversity is the assortment of species in an ecosystem.