Question

Which one of these is a living fossil?
A. Cycas
B. Ginkgo
C. Psilotum
D. All of the above

Answer 1

Fossils refers to the remains or traces of the non-degraded parts of ancient living things found within rock life preserved in the Earth’s crust. The word Fossils was derived from the Latin language ‘”fossus” meaning “dug up.”

Complete Answer:
Living fossil refers to the similarities and differences between the living organisms and fossils of extinct specimens. The term living fossil was given by an English naturalist Charles Darwin. Let us analyse each given option to find out the correct answer.

Option A: Cycas too are called “living fossils,” because they have persisted almost unchanged down the ages. However, the plant group of Cycads with around 300 species is recorded to be only a few million years old is considered by some as one of the living fossils.

Option B: A living fossil is a living species of an organism with similarities to a species which are only fossils and has no close living relatives. These species survive major extinction threats as they have low taxonomic diversities. There are a few living fossils among the plant kingdom of which Ginkgo is the most considered one.

Option C: Psilotum species is a living fossil from the time before the dinosaurs. It has leafless whisk-like branches upward and is found in tropical regions around the world. It is a descendant of the first vascular land plants, the Rhyniophytes, that appeared on earth around 400 million years ago. Its primitive nature is highlighted by its having flagellated sperm and absence of roots and leaves, unlike the more advanced flowering plants. Its lack of seeds in the reproductive cycle is another factor explaining its ancient evolutionary origin.

Hence the correct answer is option D.

Note: It is to be noted that the most famous living fossil tree is Wollemi pine, which is believed to be extinct, 200 million years old. The new discoveries suggest that the same species is alive in Australia.