Question

Neoceratodus is the connecting link between _______ and ________.
a. Cyclostomes and fish
b. Fish and amphibians
c. Amphibians and reptiles
d. None of the above

Answer 1

Hint: Neoceratodus commonly called Australian Lungfish, is the only surviving member of the family Neoceratodontidae. They are recognized as living fossils as their evolutionary history dates back to the early Devonian period. These fishes are olive green to brown in color.

Complete answer:
Neoceratodus, Australian lungfish are living fossil fishes which dates back to the early Devonian period. They are a connecting link between Fish and Amphibians as they share a close phylogenetic relationship with them.

The early members of Australian lungfish were long, with a thick, lumpy scale, a lobed and a higher degree of cranial ossification. Visible evolutionary trends in lungfish include reduced ossification with a shorter head area and a shorter body, and reappearance of dorsal fins. The scales now are thin and circular.

Adaptation: in summer, these lungfish, when they are dry hide in the mud for their summer sleep. They come back out during the rainy season. These fishes adapted this due to the bad environment.

Australian lungfish are nocturnal and carnivorous. It feeds on frogs, earthworms, pelleted food, etc. The larvae of lungfish are usually bottom feeders. They eat small Tubifex worms or filamentous algae. Respiration in lungfishes is through a single dorsal lung which supplements the oxygen supplied to it through the gills. The dentition in these fishes is quite unusual. They have two incisors, restricted to the upper jaw and are followed by dental plates on the lower jaw.

Hence, the correct answer is option (B).

Note: According to recent scientific research it is studied that formation of lungfish bones is similar to that of early human limbs. There are small protruding structures on the bone which form the fins and the bones of the fins look like a human finger or toe.