Archaeopteryx is called connecting link between reptiles and brids.

Explanation

(1) Archaeopteryx is a fossilized bird that represents the connecting link between reptiles and birds.
(2) This fossilized bird was discovered in 1861 by Andreas Wagner. The second specimen was found in 1877 and was named as Archaeronis.
(3) Archaeopteryx shows reptilian as well as avian characters.
(4) Reptilian characters :
(i) Jaws with homodont (all similar) teeth.
(ii) Ribs have a single head.
(iii) Abdominal ribs present which are like the crocodilian ribs.
(iv) Forearms have three digits ending in distinct claws while the hind limb has four digits ending in clawed digits.
(5) Avian characters :
(i) Forearms modified into wings.
(ii) Feathery exoskeleton.
(iii) Skull bones are completely fused.
(iv) Cranium is rounded with large orbits and a single condyle.
(v) Jaws are modified into beak.
(vi) Limb bones have first toe in opposable manner, Foot present with clawed digits.