Question

Archaeopteryx, a transitional fossil between birds and reptiles was discovered from the rocks of which following period?
a. Jurassic
b. Archaeozoic era
c. Cretaceous
d. Triassic

Answer 1

A connecting link is an organism that has got the characteristics of two different groups of organisms. e.g. Ornithorhynchus anatinus- a connecting link between reptiles and mammals.

Complete answer:
A connecting link represents an intermediate or transitional state of an evolutionary line between two systematic classes of species. Thus, it. Example: Seymouria and Ichthyostagia.
Archaeopteryx is a bird-like dinosaur that is the connecting link between dinosaurs and modern birds.
Archaeopteryx lived in the Late Jurassic (around 150 million years ago), in southern Germany, and also in Portugal. The largest species of Archaeopteryx measured about 0.5 m (1 ft 8 in) in length. Archaeopteryx had more characters in common with small Mesozoic dinosaurs than with modern birds. Similarities shared between shared with the dromaeosaurids and troodontids:

jaws with sharp teeth
three fingers with claws
a long bony tail
hyperextensible second toes or killing claw
feathers and various features of the skeleton

These features make Archaeopteryx a transitional fossil between non-avian dinosaurs and birds. Thus, Archaeopteryx plays an important role in the study of the origin of birds and dinosaurs.
The Jurassic period is a geological time scale that spans about 56 million years. It marks from the end of the Triassic Period 201.3 million years ago to the beginning of the Cretaceous Period 145 Mya. The Jurassic period also known as the Age of Reptiles marks the middle period of the Mesozoic era.
Archaeozoic is the geological time-scale between 3800 million years to 2500 million years ago. During this time earth's crust formed, earliest forms of life were unicellular organisms.
The first period of the Mesozoic Era was the Triassic Period. It spans between 251 million and 199 million years ago. It is marked by the great mass extinction at the end of the Permian Period. During this time living outside of the oceans began to diversify.
The Mesozoic Era was the last and longest time of the Cretaceous Period. Approximately it ranges about 79 million years. It marks the minor extinction where the Jurassic Period ends at about 145.5 million years ago.

So, the correct answer is option (A) Jurassic period.

Note: Palaeontologists consider Archaeopteryx as a connecting link between dinosaurs and birds. It shows the blend characters of aves and reptiles, it was long viewed as the earliest known bird. Its fossil was discovered in 1860, in Germany. So, in German, they called it Urvogel (German = "first bird"). Archaeopteryx term is derived from two Greek words: archaīos, meaning "ancient," and ptéryx, meaning "feather" or "wing." The fossils of two species of Archaeopteryx: A. lithographica and A. siemensii have been discovered. It lived around 150 million years ago in the late Jurassic Period — in Bavaria, Southern Germany.