Subtiliolithus is an oogenus of fossil egg from the Nemegt Formation of Mongolia and the Ohyamashimo Formation of Japan. The eggs are notable for a very thin eggshell. It contains three oospecies: S. hyogoensis, S. kachchhensis and S. microtuberculatus. They were originally classified as a distinct oofamily, Subtiliolithidae, but numerous similarities to Laevisoolithus have led to their reclassification as Laevisoolithid eggs. A complete skeleton of Nanantius valifanovi was found associated with Subtiliolithus eggshells, indicating that the oogenus represents eggs of enantiornithine birds.^[1][2][3]

Subtiliolithus Temporal range: Late Cretaceous PreꞒ Ꞓ O S D C P T J K Pg N
Egg fossil classification
Basic shell type:	Ornithoid
Morphotype:	Ornithoid-ratite
Oofamily:	†Laevisoolithidae
Oogenus:	†SubtiliolithusMikhailov, 1991 html.skin-theme-clientpref-night .mw-parser-output .infobox.biota tr{background:transparent!important}html.skin-theme-clientpref-night .mw-parser-output .infobox.biota img{background:white}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox.biota tr{background:transparent!important}html.skin-theme-clientpref-os .mw-parser-output .infobox.biota img{background:white}} .mw-parser-output .portalbox{padding:0;margin:0.5em 0;display:table;box-sizing:border-box;max-width:175px;list-style:none}.mw-parser-output .portalborder{border:solid #aaa 1px;padding:0.1em;background:#f9f9f9}.mw-parser-output .portalbox-entry{display:table-row;font-size:85%;line-height:110%;height:1.9em;font-style:italic;font-weight:bold}.mw-parser-output .portalbox-image{display:table-cell;padding:0.2em;vertical-align:middle;text-align:center}.mw-parser-output .portalbox-link{display:table-cell;padding:0.2em 0.2em 0.2em 0.3em;vertical-align:middle}@media(min-width:720px){.mw-parser-output .portalleft{clear:left;float:left;margin:0.5em 1em 0.5em 0}.mw-parser-output .portalright{clear:right;float:right;margin:0.5em 0 0.5em 1em}}html.skin-theme-clientpref-night .mw-parser-output .portalbox{background:transparent}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .pane{background:transparent}} Paleontology portal References edit ^ K. E. Mikhailov. 1991. Classification of fossil eggshells of amniotic vertebrates. Acta Palaeontologica Polonica 36(2):193-238 ^ Carpenter, K. 1999. Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past). Indiana University Press, Bloomington, Indiana. ^ Kurochkin, E.N., S. Chatterjee, and K.E. Mikhailov. (2013) "An Embryonic Enantiornithine Bird and Associated Eggs from the Cretaceous of Mongolia." Paleontological Journal 47(11):1252-1269.