Tipoolithus is another fossil egg, now from the Irbzer Formation in Morocco, and it superficially resembles other Laevisoolithid eggs laid by enantiornithenes. However, it’s not known from very good material; specifically, it is known from 12 fragments of eggshell. The shell is thin, about .4 to .65 mm thick, and it has narrow, straight, and widely spaced pores. It is covered with randomly distributed nodes on the shell, which have sharp tips.
A fossil is any evidence of life from a previous geologic age (i.e., older than 10,000 years). Most fossils are mineralized, or “turned to stone,” but this need not have occurred for an object to be a fossil. Insects in amber, Pleistocene mammoths frozen in permafrost, and even 80 million year old wood that one can light with a match are all fossils that remain very much like the original organismal remains. Fossils also include traces of the activity of organisms in the form of footprints, tooth marks, trails, burrows, and coprolites, or fossil feces. The fossil record is dominated by the hard parts of living things — bones, shells, wood, etc. — because they resist decay, but if conditions are right, almost anything can be preserved. Fossils of vertebrate internal organs and skin, jellyfish, and even the “flatulence” of protozoans actually exist!
Macroolithus is an elongated dinosaur egg genus known from the Pingling Formation in China, Mongolia, and Kazakhstan. They are known from the Maastrichtian age of the Late Cretaceous, and were probably laid by Oviraptorosaurs.
Glut, Donald F. (2003). “Appendix: Dinosaur Tracks and Eggs”.Dinosaurs: The Encyclopedia. 3rd Supplement. Jefferson, North Carolina: McFarland & Company, Inc. pp. 613–652.
Medioolithus is an egg genus known from the early Eocene in Eastern Germany. It was very similar to eggs laid by modern ratites like ostriches, rheas, and cassowaries. It was about 9 cm in diameter and was thus much smaller than eggs laid by those birds; it probably was laid by a bird more similar in size to a kiwi. It is known from eggshell fragments and one complete egg.