Origin of Birds

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INTRODUCTION

Birds are one of the most conspicuous groups of animals in the modern world. They are hugely diverse with more than ten thousand extant species distributed across the globe, filling a range of ecological niches and ranging in size from as tiny as a Humming bee to as huge as an Ostrich.

Their feathered bodies are optimized for flight, their supercharged growth rates and metabolism stands out among living animals. The ability of many bird species to imitate vocalization makes them some of the most intelligent species on the planet.

The ancestors of birds were bipedal, terrestrial, agile, cursorial and carnivorous or omnivorous. Apart from a perching foot and some skeletal fusions, a great many characters that are usually considered 'avian' (e.g. the furcula, the elongated forearm, the laterally flexing wrist and apparently feathers) evolved in non-avian theropods for reasons unrelated to birds or to flight.

During the late nineteenth and twentieth centuries the question "Where did birds evolve from and where do they fit into the family tree of life?" were hotly debated.

BIRDS ANCESTOR

During the early twentieth Century, a new hypothesis was suggested. In nineteen ten, discovery of Euparkeria (a very primitive archosaur about the size of a cat). Its discover suggested it might have been a very near the ancestor of the Dinosaurs, Pterodactyles or simply ancestors of crocodiles.

This idea was amplified by artist and natural historian Gerhard Heilmann. Heilmann examined lots of Mesozoic archosaurs. He considered coelurosaurian dinosaurs to have the most shared features with birds, but thought that they didn't have furculae or clavicles (and therefore didn't have anything that could evolve into bird clavicles).

He settled instead on Euparkeria, suggesting that it was sufficiently primitive to be a bird ancestor. His book "The Origin of Birds" published in nineteen twenty-seven in English (earlier Dutch version not as influential). Became the main hypothesis by far from the nineteen twenties until the nineteen seventies and nineteen eighties.

THE EARLIEST KNOWN BIRD

EVOLUTION OF FEATURES

EVOLUTION OF BIRDS

FLIGHT ORIGINS

BIRDS COMMON ANCESTOR CHART

WHY DID BIRDS EVOLVE

Overview

The document provides a comprehensive analysis of the origin of birds, tracing their evolutionary history from reptilian ancestors, highlighting significant fossils like Archaeopteryx, and discussing the features that define modern birds.

Key Points

1Birds evolved from theropod dinosaurs during the Mesozoic era
2Archaeopteryx is a crucial fossil linking birds to reptiles
3Two main hypotheses exist regarding the origins of flight in birds
4Modern birds belong to the group Neornithes, diverging from the extinct Enantiornithes
5The evolutionary history of birds is informed by ongoing fossil discoveries and molecular studies.

Details

Authors: Dr. Rameshori Yumnam
Category: Biology and Natural Sciences

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