Carbon-14 is useful for dating fossils that are relatively young, typically up to around 50,000 years old. Here's why:

* Half-life: Carbon-14 has a half-life of about 5,730 years. This means that every 5,730 years, the amount of Carbon-14 in a sample reduces by half.

* Dating Range: Because of the half-life, after around 50,000 years, the amount of Carbon-14 remaining in a fossil becomes too small to measure accurately.

For fossils older than 50,000 years, other dating methods like potassium-argon dating or uranium-lead dating are used.