# Monroe Creek Formation

The Monroe Creek Formation is a geologic formation in South Dakota. It preserves fossils dating back to the Paleogene period.

## Fossil content

| 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. |

### Mammals
#### Carnivorans

Carnivorans reported from the Monroe Creek Formation :
| Genus | Species | Presence | Material | Notes |
| Enhydrocyon | E. crassidens | Shannon County, South Dakota. | Crushed skull (AMNH 12886) & other skull elements. | A hesperocyonine dog. |
| Enhydrocyon | E. pahinsintewakpa | | Multiple specimens. | A hesperocyonine dog. |
| Leptocyon | L. delicatus | Porcupine Creek, South Dakota. | Left partial ramus (ACM 31102). | A canine dog, may instead be from the Harrison Formation. |
| Mammacyon | M. obtusidens | Wounded Knee Area. | Skull & partial skeleton (ACM 34-41). | A bear-dog. |
| Neocynodesmus | N. delicatus | Porcupine Creek, Wounded Knee Area. | Left mandible (ACM 31102). | Junior synonym of Leptocyon. |
| Nimravus | N. sectator | Wounded Knee Area. | Left ramus (AMNH 12882). | Possibly instead from the Harrison Formation. |
| Nothocyon | N. geismarianus | Wounded Knee Area. | Fragmentary ramus (AMNH 12872). | An arctoid formerly thought to be a canid. |
| Nothocyon | N. near latidens | Wounded Knee Area. | Jaw fragment (AMNH 12873). | Reassigned to Phlaocyon. |
| Promartes | P. gemmarosae | Wounded Knee Area. | Nearly-complete skeleton (ACM 31-33). | A mustelid. |

#### Eulipotyphlans

Eulipotyphlans reported from the Monroe Creek Formation :
| Genus | Species | Presence | Material | Notes | Images |
| Proscalops | P. sp. indeterminate | Wounded Knee Area. | Isolated molar (SDSM 5899). | A proscalopid. | |

#### Rodents

Rodents reported from the Monroe Creek Formation :
| Genus | Species | Presence | Material | Notes |
| Allomys | A. harkseni | Wounded Knee Area. | Molars. | An aplodontid. |
| Capatanka | C. brachyceps | Wounded Knee Area. | Skull (AMNH 12902). | A castorid, possibly instead from the Harrison Formation. |
| Meniscomys | M. sp. indeterminate | Wounded Knee Area. | Isolated tooth (SDSM 59157). | An aplodontid. |
| Palaeocastor | P. simplicidens | Wounded Knee Area. | Partial cranium (AMNH 12900). | A castorid. |
| Pleurolicus | P. dakotensis | Wounded Knee Area. | Left ramus (AMNH 12893). | A gopher. |
| Promylagaulus | P. cf. riggsi | Wounded Knee Area. | Isolated molar. | A mylagaulid. |

#### Ungulates

Ungulates reported from the Monroe Creek Formation :
| Genus | Species | Presence | Material | Notes | Images |
| Nanotragulus | N. ordinatus | Wounded Knee Area. | Mandibles. | May instead be from the Harrison Formation. | |
| Parahippus | P. pristinus | Wounded Knee Area. | Hind feet (AMNH 12922). | May instead be from the Harrison Formation. | |

### Reptiles
#### Squamates

Squamates reported from the Monroe Creek Formation :
| Genus | Species | Presence | Material | Notes | Images |
| Peltosaurus | P. granulosus | Sharps Corner, South Dakota. | Multiple specimens. | A glyptosaurine also known from the Sharps Formation. | |