Eomonorachus fossil map
Where fossils of Eomonorachus have been found, shown on the Earth as it looked about 445 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 445 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 | Trilobites & sea scorpions |
|---|---|
| Lived | 457.3–449.6 million years ago (Sandbian to Katian) |
| Periods | Ordovician |
| Family | Pterygometopidae |
| Named by | Delo 1935 |
| Fossil records | 23 occurrences at 8 locations (PBDB) |
| Found in | United States, Canada |
| Rock formations | Martinsburg, Guttenberg, Spechts Ferry, Scales Shale, Ion, Cummingsville |
About Eomonorachus
Eomonorachus is a genus of trilobites in the order Phacopida, that existed during the middle Ordovician in what is now the United States. It was described by Delo in 1935, and the type species is Eomonorachus intermedius, which was originally described under the genus Dalmanites by Walcott in 1877. It also contains the species Eomonorachus divaricatus, which was originally assigned to Calliops by Frederickson in 1964, and was later moved to Estoniops by Shaw in 1974, before being reassessed under its current genus by Ludvigsen in 1978. The type locality was the Decorah Formation in Minnesota.
Text in “About” is quoted from the Wikipedia article Eomonorachus (revision 1321663946), 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: Q136764825.
