Well, we don't know because of what's known as the egg gap. Some of our earliest fossil records of amniote eggs are from dinosaurs, like mussaurus patagonicus, which lived around 250 million years ...

The age-old debate of whether the chicken or the egg came first is explored through historical and evolutionary contexts.

Sander argues that egg-laying actually came first. He suggests that early leathery amniote eggs did not fossilize well. As such, evidence of egg-laying amniotes would be scarce at best, Sander said.

Most biologists will answer confidently when asked "which came first, the chicken or the egg?" but the answer may depend on what type of egg you're talking about.

The amniotic egg consists of a suite of fetal membranes, including the amnion, chorion and allantois, as well as an external shell that can be either strongly mineralized (as in rigid-shelled eggs ...

The claim stood until 1979, when a second look at the fossil egg suggested it actually lacked the features of an amniote egg.

Sander argues that egg-laying actually came first. He suggests that early leathery amniote eggs did not fossilize well. As such, evidence of egg-laying amniotes would be scarce at best, Sander said.

This just in: The scientists have solved it. After a millennium of taunting young biologists and philosophers as Plutarch pondered: “Which was first, the bird or the egg?” the great chicken ...

'But the amniotic egg was the key. 'It was said to be a "private pond" in which the developing reptile was protected from drying out in the warm climates and enabled the Amniota to move away from ...