Mammals
- Shrews (several taxa)
- Moles
- Small weasel
- Arctomeles dimolodontus (prehistoric badger) NEW SPECIES
- Pristinailurus bristoli (prehistoric Red panda) NEW SPECIES
- Short-faced bears of the genus Plionarctos
- Saber-toothed cats are represented by a single part of a tooth, possibly from Machairodus.
- Shovel Tusked Elephants, or gomphotheres, are also present at the site. At the time it is unknown which species they belong to, but it is most likely that they belong to Amebelodon or a similar genus.
- Teleoceras A species of hippo-like rhino common in other parts of the continent during the same time period, and lived a lifestyle similar to the modern-day hippopotamus. Several complete skeletons have been unearthed.
- Prehistoric camel, possibly a member of the genus Megatylopus.
- Tapirus polkensis (prehistoric tapir) Found in large numbers at the site, including juvenile specimens.
- Peccary (of the genus Tayassu for the Collared Peccary and the White-lipped Peccary and the genus Catagonus for the Chacoan peccary)
- Rabbits
- Rodents (several taxa)
- Extinct Beaver of the genus Dipoides.
- Ground Sloth (genus and species unknown)
- Three-Toed Horse (genus and species unknown)
Read more about this topic: Gray Fossil Site, Fossil Fauna