Iaceornis fossil map
Where fossils of Iaceornis have been found, shown on the Earth as it looked about 85 million years ago and on today’s map.
Dots are fossil collections recorded in the Paleobiology Database. The “then” view moves today’s fossil sites back to their positions 85 million years ago (the time slice nearest the median age of the fossils) using the Merdith et al. (2021) plate model; positions are approximate. Open on the timeline map →
| Group | Theropods |
|---|---|
| Lived | 85.7–83.6 million years ago (Santonian) |
| Periods | Cretaceous |
| Named by | Clarke 2004 |
| Fossil records | 1 occurrences at 1 locations (PBDB) |
| Found in | United States |
| Rock formations | Niobrara |
About Iaceornis
Iaceornis is a genus of marine ornithuran dinosaurs closely related to modern birds. It was endemic to North America during the Late Cretaceous, living about 83.5 million years ago. It is known from a single fossil specimen found in Gove County, Kansas, and consisting of a partial skeleton lacking a skull.
Since it was first discovered by Othniel Charles Marsh in 1877, the specimen (YPM 1734) was long considered to belong to the contemporary species Apatornis celer. Because it is relatively complete, most discussions of Apatornis actually focused on the Iaceornis fossil. In 2004, paleontologist Julia A. Clarke showed that the skeleton actually differed in important characteristics of the wing bones from the true, holotype specimen of Apatornis. Therefore, she assigned the more complete remains to a new genus and species, Iaceornis marshi, meaning "Marsh's neglected bird".
In Clarke's phylogenetic analysis, she found that Iaceornis is more advanced than Ichthyornis but less advanced than modern birds.
Text in “About” is quoted from the Wikipedia article Iaceornis (revision 1379676788), licensed under CC BY-SA 4.0; introduction excerpted verbatim, formatting removed. Ages, family, authority and fossil records: Paleobiology Database, accessed 23 October 2026. Ages are those of the rock layers the fossils were found in. Wikidata: Q5980282.
