Archaeopteryx – The First Bird`s Fossil

Archaeopteryx – The First Bird`s Fossil

The first fossil of bird or Archaeopteryx lithographica was discovered by Andreas Wagner in 1861 in the lithograohic slate quarries of Solenhofen in Bavaria (Germany). It is now kept in British Museum. In 1877 another specimen was discovered from the same locality and was named Archaeornis siemensi, now kept in Berlin Museum. Archaeopteryx was a small bird about the size of a crow or pheasant, but with long lizard-like tail-bearing feathers. It exhibits both reptilian and avian (birds) features. If we compare and talk about characters of both, reptilian and avian, then this gives us a better understanding. So, let`s start...

Reptilian Characters of Archaeopteryx

1. The skeletal bones are not pneumatic.

2. The jaws are provided with homodont reptilian type of teeth.

3. Vertebrae are articulated by simple concave facets (amphicoelous).

4. Cervical and thoracic ribs are single-headed and without uncinate processes. Abdominal ribs like those of sphenodon and crocodile are present.

5. Sternum is without a keel.

6. The long tail is composed of about 20 caudal vertebrae which are free.

7. Metacarpal bones are separate and carpo-metacarpus bone is absent.

8. The three digits of the hand are clawed. The number of phalanges are 2, 3 and 4 in the first, second and third digits as in reptiles.

9. Fibula is as long as the tibia.

10. Pelvic girdle is of reptilian type with elongated ilium and backwardly directed pubis.

11. Body and limbs bear scales.

Avian Characters of Archaeopteryx

1. There are feathers covering the body.

2. Forelimbs are modified to form wings.

3. Skull is monocondylic and bears large orbits. Brain box is large.

4. Elongated jaws are present in the form of beaks.

5. The scapulae are slender, curved bones.

6. Furcula or wish-bone is present.

7. Hind limbs are bird-like having four clawed toes. Hallux is opposable.

8. Two rows of tall feathers or rectrices are present.

On the basis of the three-fold evidence enumerated above, it can be safely concluded that the birds and the reptiles are very closely related and that the birds have evolved from some reptilian stock. The ancestral birds which had an underlying layout of reptiles underwent further modification in the course of evolution due to the new mode of aerial life. Thus the flight adaptation may be regarded as the glorification of birds because these adaptive modifications actually led to the evolution of birds from reptiles. The characters which glorify birds are as follows:

1. Development of feathers.

2. Modification of forelimbs into wings.

3. Efficient lungs with air sacs.

4. Completely four-chambered heart with double circulation providing requisite energy for flight.

5. Warm-bloodedness, with high body temperature.

6. Light skeleton.

7. Development of flight muscles.

8. More developed brain, and

9. Developed sense of sight and hearing.

So, it can be concluded that birds while retaining many reptilian characters, have undergone modification in their functional anatomy and added some adaptive characters which enable them to lead superior life or glorified life.

Reference

1. Britannica Reference Encyclopaedia

2. Knowledge Encyclopedia Animal!: The Animal Kingdom as you've Never Seen it Before

3. Images are taken from Zoo-Que and Google.

4. In Defense of Plants: An Exploration Into the Wonder of Plants

5. A Naturalist’s Guide to the Birds of India

6. Earth: A Sustainable Planet

Also See

• Migration & Navigation of Birds

• Archaeopteryx – The First Bird`s Fossil

• Parrots

• Bats