All Archaeopteryx specimens were believed to represent the remains of floating carcasses that sunk to the bottom of Jurassic lagoons in an area called Solnhofen, in Germany.
However, two specimens of this extinct animal, known as the Berlin and Teylers specimens, are shown here to lie atop of radiodense and non-rigid fossilized eggs averaging 1,3 cm in their longer axis, some containing directly visible fetuses with surface morphology preservation.
One of such egg-enclosed fetuses shows a toothed beak.
X-ray evidence of a similar egg in a third specimen – the mysteriously disappeared Maxberg specimen for which X-rays are available – is also presented.
These eggs are in the size range of Archaeopteryx’s pelvic opening and also of hatchlings described in Volume II of this book.
This first volume exposes the existence of non-rigid eggs in the bird lineage, raising important questions about the origin of birds and opening new possibilities for research in reproduction (the process by which living organisms give rise to others), development (the process by which new adult organisms are formed from single cells) and evolution (the process by which heritable features progress from generation to generation).