Sunday, 13 March 2011

The first birds


Archaeopteryx

It was the first bird in the history, this bird, appeared during the Mesozoic, in the Jurassic era and it is supposed to be the missing link between dinosaurs and birds. Archaos means ancient and pteryx means wings.

The first complete fossil of the archaeopteryx was found in 1862, three years after Charles Darwin had published “The origin of the species”, this discover became a proof of evolution to support the Darwin-Wallace theory.

It was 35 cm tall and had the basic characteristics of a dinosaur theropod. They have a long duration of their teeth, feathers in their body and wide ones in their tails, they also had claws in their fingers and bones and a long caudal appendage that has been disappearing from nowadays birds. It isn’t clear the color of their feathers.

(Recreation of the Archaeopteryx)

Iberomesornis romerali

It can be found the missing link between the Archaeopteryx and the modern birds.

It has the measure of a sparrow and it had vertebrae joined in its tail and bones from the shoulder in their waist. Similar characteristics to the Archaeopteryx are: the capability to fly flapping their wings, bones in their hips and posterior tips.

Other theories

There are other theories about the first birds; one of them was discovered few years ago in which some scientist say that the first bird appeared 235 million years ago, it was a lizard-like animal, which grew up to 2ft (60,97 cm) , this animal was known as kuehneosaurs, they had an extension in their ribs that they used as wings for gliding.

Pterosaurs

During all the life the only vertebrate animals able to fly have been: bats, pterosaurs and birds.

The pterosaurs come from archosaurs and near members of the dinosaurs. They are characterized by their wider sternum than the birds. The also had hollow bones. Their wings were sustained by their fourth finger that was much longer than the others. From this finger, a membrane went out, what they used as a wing. The bats sustained their wings with four fingers and the birds, the only ones with feathers, sustained their wing with two fingers.

Actually, there are four types of pterosaurs known, classifying them by their aliments: the ones that ate insects, those who ate fish, those who filter plankton and those who fed from corpses (from here come the theory of Quetzalcoatlus). They used to have the size of a dove from a size of a vulture. There were two exceptions that had a bigger size: the Pteranodon and the Quetzalcoatlus mentioned before.

The Quetzalcoatlus could reach the size of 5 metres and had a crest that went to the opposite side. The Quetzalcoatlus’s wingspan went from 12 to 17 metres. Is said that this type of birds used heating currents of air to fly, because they couldn’t lift their own weight just flapping their wings.

The birds come from the same ancestor that reptiles, here there is a case of adaptive divergence.

Bibliography

- Dinosaurios - Museo Nacional de Ciencias Naturales

- http://es.wikipedia.org/wiki/Archaeopteryx

- Google searchs

-http://www.dailymail.co.uk/sciencetech/article-1035328/Scientists-discover-worlds-bird-lived-235million-years-ago.html



By Rubén Iglesias and Daniel Ribeiro

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