Paleozoic limestone xenoliths have been recovered from kimberlite pipes that intrude the Archean Canadian Shield. Xenoliths from the Jericho pipe in the central Slave craton are commonly fossiliferous and contain a diverse macrofauna and microfauna, including conodonts. Most of the 21 conodont collections that have been recovered are Middle Devonian in age (late Eifelian to early Givetian, and early to middle Givetian). In general, the fauna is indicative of deposition in shallow- and open-marine environments; a few collections are indicative of slightly restricted shoal-shelf seas. A few low-diversity conodont suites could be pre-Middle Devonian. The nearest similar Paleozoic rocks are more than 400 km to the southwest of the Jericho pipe in the foothills of the Mackenzie Mountains. The Jericho limestone xenoliths provide the only solid evidence that shallow Middle Devonian seas inundated the now-exposed Slave craton of the Canadian Shield.