That's because when something becomes a new species is a surprisingly difficult and contentious debate in biology.

That's simply due to the nature of evolution. It's nearly impossible to look at one past generation of chicken to the next to figure out when the ancestor was no longer a chicken. Yet, go back far enough and you'll find T-Rexes in the mix.

Every generation is a new missing link. It's an extremely fuzzy process.

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technothrasher 19 minutes ago | parent | next [-]

This is because "species" is a taxonomical category that we invented, but that does not actually map cleanly to reality.

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usrnm 3 hours ago | parent | prev | next [-]

> Yet, go back far enough and you'll find T-Rexes in the mix

Afaik, T-Rex was never a direct ancestor of modern birds, including chicken. T-Rex and birds are theropod dinosaurs, but it was a very large and diverse group of animals.

	▲	thaumasiotes an hour ago \| parent [-]
		But as soon as you've gone up from a chicken to the ancestor of a T-Rex, you do indeed find that T-Rexes are in the mix. They look different from what you'd normally think of as a T-Rex, in the same way that they also look different from what you'd normally think of as a chicken.

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b112 3 hours ago | parent | prev | next [-]

Greg Bear and his fancy pants radio says otherwise.

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b00ty4breakfast 2 hours ago | parent | prev [-]

turns out evolution is analog