''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 of t ...

dinosaur egg Dinosaur eggs are the organic vessels in which a 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 laid eggs bec ...

from the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

(

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 132.9 ± 2 Ma and 129.4 ± 1.5 Ma (million years ago). The Hauterivian is preceded by the Va ...

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from ...

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

troodontids Troodontidae is a clade of bird-like theropod dinosaurs. During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinosaurian lineages. More recent fossil discov ...

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