# John Day Formation

The John Day Formation is a series of rock strata exposed in the Picture Gorge district of the John Day River basin and elsewhere in north-central Oregon in the United States. The Picture Gorge exposure lies east of the Blue Mountain uplift, which cuts southwest–northeast through the Horse Heaven mining district northeast of Madras. Aside from the Picture Gorge district, which defines the type, the formation is visible on the surface in two other areas: another exposure is in the Warm Springs district west of the uplift, between it and the Cascade Range, and the third is along the south side of the Ochoco Mountains. All three exposures, consisting mainly of tuffaceous sediments and pyroclastic rock rich in silica, lie unconformably between the older rocks of the Clarno Formation below and Columbia River basalts above.

## Stratigraphy

The strata, which vary in age from 39 million years to 18 million years, were formed mainly from ashfalls from volcanoes due to a series of calderas now linked to the Yellowstone hotspot. Some of the major layers within the group exposed in the Picture Gorge district are the Big Basin Formation and Bridge Creek Beds (35 to 32 million years), the Turtle Cove Formation (30 to 28 million years), the Picture Gorge Ignimbrite (28.7 million years), the Kimberly Formation (28 to 25 million years), and the Haystack Formation (25 to 18 million years).
Located in the general vicinity of what became the Cascade Range, the John Day volcanoes emitted large volumes of ash and dust, much of which settled in the John Day basin. The rapid deposition of the ash preserved the remains of plants and animals living in the region. Some of the solidified ash and the fossils they contain are found in the John Day Fossil Beds National Monument. Because ash and other debris fell during varied climatic and volcanic conditions and accumulated from many eruptions extending into the early Miocene (about 20 million years ago), the sediment layers in the fossil beds vary in their substance, chemical composition and color. The lowermost layer contains red ash, such as that exposed in the Painted Hills Unit of the national monument. The layer above it is mainly pea-green clay. On top of the pea-green layer are buff-colored layers.

## Paleontology

| Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon | Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited. |
Fossils found in the John Day Formation include a wide variety of plants and more than 100 species of mammals, including dogs, cats, oreodonts, horses, camels, and rodents. Among the notable plant fossils are Metasequoia (Dawn Redwood), a genus thought to have gone extinct worldwide until it was discovered alive in China in the early twentieth century.
Among the paleobiota found in the formation is the Daeodon, whose type species, Daeodon shoshonensis, has been found in the formation.

### Mammals
#### Apatotheres

Apatotheres reported from the John Day Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Sinclairella | S. dakotensis | Blue Basin, Grant County, Oregon. | Turtle Cove Member. | Lower right incisor (JODA 15846) & upper right second molar (JODA 15850). | An apatemyid. | |

#### Carnivorans

Carnivorans reported from the John Day Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes |
| Archaeocyon | A. pavidus | Picture Gorge 30, Blue Basin level 1. | Turtle Cove Member. | Maxillary & mandible fragments (UCMP 76652). | A borophagine dog. |
| Cormocyon | C. copei | Wheeler & Grant counties, Oregon. | Turtle Cove Member. | Numerous specimens. | A borophagine dog also known from the Troublesome Formation. |
| Corumictis | C. wolsani | Grant County, Oregon. | Turtle Cove & Kimberly members. | A nearly complete skull (JODA 8167) & a right dentary (JODA 396). | A small mustelid. |
| Cynarctoides | C. lemur | Wheeler & Grant counties, Oregon. | Turtle Cove Member. | Skull & jaw elements. | A borophagine dog also known from the Brule, Sharps & Browns Park formations. |
| Daphoenodon | D. robustum | Grant County, Oregon. | Rose Creek Member. | Teeth & astragalus. | A bear-dog also found in the Runningwater & Zia Sand formations. |
| Desmocyon | D. thomsoni | | Probably from the Haystack Valley Member. | Isolated right molars (AMNH 7238). | A borophagine dog also known from the Harrison Beds, Runningwater Formation & Zia Formation. |
| Dinaelurus | D. crassus | | Turtle Cove Member. | A mostly complete cranium. | A nimravid. |
| Dinictis | D. felina | | Turtle Cove Member. | | A nimravid. |
| Enhydrocyon | E. basilatus | Grant & Wheeler counties. | ?Kimberly Member. | Skull and jaws. | A hesperocyonine dog also known from the Harrison Formation. |
| Enhydrocyon | E. sectorius | Central Oregon, no detailed locality given. | | Fragment of right maxillary (AMNH 6905). | A hesperocyonine dog. |
| Enhydrocyon | E. stenocephalus | Grant County, Oregon. | Turtle Cove Member. | 4 skulls. | A hesperocyonine dog. |
| Hoplophoneus | H. cerebralis | | Turtle Cove Member. | | A nimravid. |
| Hoplophoneus | H. strigidens | | Exact stratigraphic level unknown. | AMNH 6942, medial fragment of an upper canine. | A nimravid. |
| Leptocyon | L. douglassi | Between the Picture Gorge Ignimbrite & Deep Creek Tuff. | Turtle Cove Member. | Anterior part of skull (UCMP 79365). | A canine dog also known from the Toston & Sharps formations. |
| Leptocyon | L. mollis | Turtle Cove, John Day River, Grant County, Oregon. | Turtle Cove Member. | Skull (UCMP 90). | A canine dog. |
| Leptocyon | L. vulpinus | Wheeler County, Oregon. | Haystack Valley Member. | Fragment of right ramus. | A canine dog also known from the Harrison & Runningwater formations. |
| Machaerodus | M. cerebralis | | Turtle Cove Member. | A mostly complete cranium. | Reassigned to Hoplophoneus. |
| Mesocyon | M. brachyops | | May be from the Turtle Cove Member. | Skull elements & pelvis. | A hesperocyonine dog. |
| Mesocyon | M. coryphaeus | | Turtle Cove Member. | Numerous specimens. | A hesperocyonine dog. |
| Nimravus | N. brachyops | | Turtle Cove & Kimberly members. | | A nimravid. |
| Palaeogale | P. dorothiae | | Kimberly Member. | A left and a right dentary from separate individuals. | A palaeogalid. |
| Palaeogale | P. sp. | | Turtle Cove Member. | A largely complete cranium. | A palaeogalid & the oldest known occurrence of the genus in the Pacific Northwest. |
| Paradaphoenus | P. cuspigerus | | | Skull elements. | A bear-dog. |
| Paraenhydrocyon | P. josephi | Grant County, Oregon. | Turtle Cove Member. | Skull elements. | A hesperocyonine dog. |
| Paraenhydrocyon | P. wallovianus | "John Day Badlands, Oregon". | May be from the Turtle Cove Member. | Crushed rostral part of skull (AMNH 6858). | A hesperocyonine dog also known from the Marsland & Harrison formations. |
| Philotrox | P. condoni | Turtle Cove & Morgan Locality, Oregon. | Turtle Cove Member. | Skulls & vertebrae. | A hesperocyonine dog also known from the Sharps Formation. |
| Phlaocyon | P. latidens | Grant & Wheeler counties, Oregon. | Turtle Cove Member. | Jaw elements. | A borophagine dog. |
| Pogonodon | P. davisi | | Turtle Cove & Kimberly members. | Skull elements. | A nimravid also known from the White River, Brule & Sharps formations. |
| Pogonodon | P. platycopsis | | Turtle Cove Member. | Skull elements. | A nimravid also found in the White River Group & Brule Formation. |
| Rhizocyon | R. oregonensis | Wheeler & Grant counties, Oregon. | Turtle Cove Member. | Skulls & jaw elements. | A borophagine dog. |

#### Eulipotyphlans

Eulipotyphlans reported from the John Day Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Micropternodus | M. morgani | Courtrock quadrangle, Grant County, Oregon. | Middle beds. | Rostrum (UCMP 60801). | A soricomorph. | |

#### Metatherians

Metatherians reported from the John Day Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Herpetotherium | H. merriami | Logan Butte, Crook County, Oregon. | | Partial skull with teeth & mandible (UCMP 24240). | A herpetotheriid. | |

#### Rodents

Rodents reported from the John Day Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes |
| Allotypomys | A. pictus | Grant & Wheeler counties. | Turtle Cove & possibly Kimberly members. | Jaw elements & teeth. | An eutypomyid. |
| Apeomys | A. whistleri | Campbell Ranch, Gilliam County, Oregon. | Kimberly Member. | Jaw elements & teeth. | An eomyid. |
| Bursagnathus | B. aterosseus | Grant County, Oregon. | Johnson Canyon & Rose Creek members. | 2 nearly-complete skulls. | A perognathine. |
| Leptodontomys | L. sp. | Campbell Ranch, Gilliam County, Oregon. | Kimberly Member. | Partial right dentary (JODA 12699). | An eomyid. |
| Microtheriomys | M. brevirhinus | Grant County, Oregon. | Turtle Cove Member. | Skull elements. | A castorid. |
| Miosciurus | M. ballovianus | Grant, Wheeler & Gilliam counties, Oregon. | Turtle Cove, Kimberly & Haystack Valley members. | Jaw elements & crushed skulls. | A squirrel. |
| Miosciurus | M. covensis | Crook & Grant counties, Oregon. | Turtle Cove Member. | Jaw elements. | A squirrel. |
| Miosciurus | M. sp. | Hayes Haven, Grant County, Oregon. | Turtle Cove Member. | Right partial dentary & associated postcranial fragments (JODA 4447). | A squirrel. |
| Mookomys | M. sp. | Wheeler County, Oregon. | Haystack Valley Member. | Partial maxilla & left distal femur (JODA 7900). | A heteromyid. |
| Neoadjidaumo | N. arctozophus | Crook & Grant counties, Oregon. | Turtle Cove Member. | Left dentary (JODA 16005) & right dentary (JODA 3615). | An eomyid. |
| Palaeocastor | P. fossor | Grant & Wheeler counties. | Kimberly, Haystack Valley & possibly Johnson Canyon members. | Skull elements. | A castorid. |
| Petauristodon | P. sp. | Campbell Ranch, Gilliam County, Oregon. | Kimberly Member. | Left molar (JODA 12597). | A flying squirrel. |
| Plesiosminthus | P. fremdi | Campbell Ranch, Gilliam County, Oregon. | Kimberly Member. | Jaw elements. | A sicistine. |
| Proapeomys | P. condoni | Grant & Crook counties, Oregon. | Turtle Cove Member. | Dentary & teeth. | An eomyid. |
| Proapeomys | ?P. lulli | Hayes Haven, Grant County, Oregon. | Turtle Cove Member. | Partial dentary (YPM 10573) & dentary fragment (JODA 16002). | An eomyid originally reported as Florentiamys lulli & Jimomys lulli. |
| Proheteromys | P. latidens | Gilliam County, Oregon. | Kimberly Member. | Multiple specimens. | A heteromyid. |
| Proheteromys | P. thorpei | Grant & Gilliam counties, Oregon | Turtle Cove & Kimberly members. | Partial dentaries & teeth. | A heteromyid. |
| Protosciurus | P. mengi | Grant, Gilliam & Wheeler counties, Oregon. | Turtle Cove, Kimberly & Haystack Valley members. | Multiple specimens. | A squirrel. |
| Protosciurus | P. rachelae | Grant, Gilliam & Wheeler counties, Oregon. | Turtle Cove & Kimberly members. | A nearly complete skull (UCMP 86367) & several teeth. | A squirrel. |
| Tenudomys | T. sp. | Grant County, Oregon. | Haystack Valley Member. | Left dentary (JODA 3548). | A geomyoid. |
| Trogomys | T. oregonensis | Hayes Haven, Grant County, Oregon. | Turtle Cove Member. | Left dentary (JODA 4534). | A heteromyid. |

#### Ungulates

Ungulates reported from the John Day Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes |
| Daeodon | D. shoshonensis | Bridge Creek, Wasco County, Oregon. | | Symphyseal fragment (AMNH 7387). | An entelodont. |
| Desmatochoerus | D. curvidens | North Fork, John Day River, John Day Valley. | ?Middle John Day deposits. | Partial skull & mandible (YPM 10997). | An oreodont. |
| Desmatochoerus | D. leidyi | John Day Valley. | Upper John Day. | Multiple specimens. | An oreodont. |
| Diceratherium | D. annectens | | | Numerous specimens. | A rhinoceros. |
| Diceratherium | D. armatum | | | Numerous specimens. | A rhinoceros. |
| Diceratherium | D. niobrarense | | | Numerous specimens. | Specimens reassigned to D. armatum & D. annectens. |
| Gentilicamelus | G. sternbergi | "The Cove" and possibly other localities. | Upper John Day Beds & possibly other parts of the Turtle Cove & Kimberly members. | Multiple specimens. | A camelid. |
| Fremdohyus | F. osmonti | "About 6 miles north of Clarno's Ferry, Gilliam County, Oregon". | "Diceratherium beds, Middle John Day". | A nearly complete skull & mandible (UCMP 393). | A peccary. |
| Marshochoerus | M. socialis | | Level unknown but presumed to be late Arikareean. | Associated molars. | A peccary. |
| Moropus | M. oregonensis | | Rose Creek Member. | Teeth & foot bones. | A chalicothere. |
| Moropus | M. sp. | | Rose Creek Member. | A juvenile maxilla. | A chalicothere. |
| Oreodontoides | O. (Paroreodon) marshi | | Middle John Day. | 10 specimens. | An oreodont. |
| Oreodontoides | O. oregonensis | | ?Middle John Day. | 14 specimens. | An oreodont. |
| Oreodontoides | O. (Paroreodon) stocki | | | 10 specimens. | An oreodont. |
| Pseudodesmatochoerus | P. wascoënsis | Wasco County, Oregon. | Middle or upper John Day. | Partial skulls. | An oreodont. |
| Superdesmatochoerus | S. lulli | Turtle Cove, John Day Valley. | Upper John Day. | Multiple specimens. | An oreodont. |
| Superdesmatochoerus | S. microcephalus | | Middle John Day. | 6 specimens. | An oreodont. |
| Thinohyus | T. lentus | | Unknown level. | Broken juvenile skull (YPM 11783). | A peccary. |
| Thinohyus | T. rostratus | | Unknown level. | A complete skull (AMNH 7395). | A peccary. |

### Reptiles
#### Squamates

Squamates reported from the John Day Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Dyticonastis | D. rensbergeri | North-central Oregon. | Uppermost Turtle Cove Member. | UCMP 76878-76883. | A worm lizard. | |