''Prismatoolithus'' is an

oogenus Egg fossils are the fossilized remains of eggs laid by ancient animals. As evidence of the physiological processes of an animal, egg fossils are considered a type of trace fossil. Under rare circumstances a fossil egg may preserve the remains ...

dinosaur egg Dinosaur eggs are the organic vessels in which a dinosaurs, dinosaur embryo develops. When the first scientifically documented remains of non-avian dinosaurs were being described in England during the 1820s, it was presumed that dinosaurs had la ...

from the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

(

Hauterivian The Hauterivian is, in the geologic timescale, an age in the Early Cretaceous Epoch or a stage in the Lower Cretaceous Series. It spans the time between 132.6 ± 2 Ma and 125.77 (million years ago). The Hauterivian is preceded by the Valangi ...

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

) and possibly also the earliest Paleocene. They likely belonged to

troodontids Troodontidae is a clade of bird-like theropod dinosaurs from the Late Jurassic to Late Cretaceous. During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinos ...

.Mateus, I, H Mateus, MT Antunes, O Mateus, P Taquet, V Ribeiro, G Manuppella. 1998. Upper Jurassic theropod dinosaur embryos from Lourinhã (Portugal). Memórias da Academia das Ciências de Lisboa 37, 101-110

References

Dinosaur reproduction Egg fossils Fossils of Canada Paleontology in Alberta Fossils of China Fossils of France Fossils of Japan Fossils of Mexico Fossils of Morocco Fossils of Spain Tremp Formation Fossils of the United States Paleontology in Montana Paleontology in New Mexico Paleontology in Utah Milk River Formation Fossil parataxa described in 1993 {{eggshell-stub