Question

A primitive mammal-like fossil reptile of the Carboniferous period was:
(a) Dimetrodon
(b) Ramapithecus
(c) Rhynchocephalia
(d) Stegosaurus

Answer 1

Hint: The Carboniferous period is a period of the Palaeozoic era. It is known as the age of amphibians and the first reptiles and cockroaches appear. A primitive mammal- like fossil reptile of the Carboniferous period is famously known for its row of large spines on the back.

Complete answer:
Geological time scale is a chronological sequence of geologic and evolutionary events covering the physical formation and development of the earth. Dimetrodon is an extinct carnivorous non- mammalian synapsid or primitive mammal- like reptile. They are thought to originate in the Permian period before the Carboniferous period. They have large extensions of the vertebral column in the back in the form of spines. They are thought to be helpful for thermoregulation.
- Ramapithecus is regarded as the ancestor of orangutans. The fossils of these primate apes were found in the foothills of Shivalik Himalayas. They are supposed to belong to the Cenozoic era.
- Rhynchocephalia is an order under the subclass Diapsida of Reptiles. They are represented by only one species which is Sphenodon or Tuatara. They are only found in the small set of coasts of New Zealand. Superficially, they resemble that of lizards, but many differences set them apart like the existence of a third eye in the juvenile form. This third eye helps it to judge the time or duration of the day. Also, a row of spine- like short structures runs superiorly on its body.
- Stegosaurus is a herbivore dinosaur that lived around 144 million years ago in the Late Jurassic period. Compared to its large size, it had a short head and neck that allowed it to eat only low- lying vegetation like bushes. Bony porous plates called scutes were arranged at short intervals over its back and tail.

So, the correct answer is “(a) Dimetrodon”.

Note:
- The complete life span of Earth is 4600 million years. This is known in simple terms as the geological time.
- The geological time scale is divided into the era, period, and epoch. Among them, an epoch is the smallest unit of geological time scale.
- It was developed by Giovanni Ardulna, an Italian scientist in 1760.