Why is the prehistoric bird (Archaeopteryx) a good (prime) example of a bridge animal?

The Urvogel Archaeopteryx lithographica is therefore a good example of a bridge-organism because it very clearly explains the term bridge-organism. There are a whole range of fossils of this type, which are really very excellent and where the mixture of original (plesiomorphic) features of the “reptil” ancestors and derived (apomorphic) features of the birds can therefore be seen very well. Particularly good is obtained e.g. the “Berliner Exemplar”, which is exhibited in the original at the Naturkundemuseum Berlin. Like all Archaeopteryx-Fossilien was originally in about 150 million. Years of old plate limestone found in the area around Solnhofen and Eichstätt.

The Archaeopteryx is also remarkable, because only a few years after the first release of Charles Darwin’s main work On the Origin of Species (1859) found a fossil of the Urvogel for the first time in 1861 and was first described by Hermann Meyer. This led to Thomas Henry Huxley, one of Darwin’s most loyal advocates of evolution theory, already in 1868 by comparing Archaeopteryx– fossils with those of Compsognathus (a small, two-legged predatory species) and with the skeletons of modern birds realized that the modern birds must have developed from non-aircrafted dinosaurs.

The plesiomorphic features include:

• instead of a beak a beak with teeth
• there is no bone breast with a breast
• the middle-foot bones (Metatarsalia) are only partially fused with the root bones (Tarsalia) to a Tarsomeratarsus
• a knöcher cock
• on each hand three fingers with claws

Derived bird characteristics are:

• Parts of the root bones are fused with the tibia to the tibiotarsus
• Spring dress with asymmetric swing springs that enabled an active rowing flight
• the key legs are merged into a bone, the furcula (gabelbone)
• the first toe can be compared to the other (but incompletely)