Which one of the following is a living fossil?

Question

Accepted Answer

The correct option is 1:

Ginkgo biloba, often referred to as the "maidenhair tree," is indeed a classic example of a living fossil. This term is applied to species that have remained largely unchanged morphologically over millions of years and have close relatives known only from the fossil record. Ginkgo is a gymnosperm with a unique fan-shaped leaf and a fossil record dating back to the early Jurassic period, approximately 170 million years ago, as highlighted by recent palaeobiological studies. Its remarkable resilience and consistent form through significant geological eras make it a prime example of evolutionary stasis, providing a living window into ancient plant life. The survival of Ginkgo in its essentially modern form for such a vast period, while many of its contemporaries became extinct, underscores its unique status.

The incorrect option is 2:

Ephedra is a genus of gymnosperms, but it is not considered a living fossil. While it has ancient lineages, its evolutionary history and morphological changes do not fit the strict definition of a living fossil as closely as Ginkgo. Ephedra species have undergone more significant diversification and evolutionary changes compared to Ginkgo.

The incorrect option is 3:

Taxus, commonly known as yew, is another genus of gymnosperms. Although yew trees are long-lived and have a relatively ancient origin, they do not possess the same degree of evolutionary stasis and a fossil record gap that would classify them as living fossils in the same vein as Ginkgo. Their morphology and distribution have shown more adaptive changes over geological time.

The incorrect option is 4:

Abies, or fir trees, are coniferous gymnosperms. These trees are part of a more evolutionarily dynamic group within the conifers. While conifers are ancient, Abies itself represents a more modern diversification within the conifer lineage and does not exhibit the prolonged morphological stability required to be designated a living fossil.