The first known bird fossil date to the mesozoic era of time.
Step-by-step explanation:
- The first known bird fossil is Archaeopteryx.
- Archaeopteryx were not exactly like modern birds and are called dinosaur like birds..
- Carbon dating suggest that these birds evolved during the jurassic period of mesozoic era.
- These are considered as the only birds of that era.
- Ancestors of modern birds began to evolve during cretaceous period and kept on evolving through Cenozoic era.