Reeve's Bonebed


Reeve's Bonebed is a geological formation in Presidio County, Texas, with the coordinates of 29.9° N, 104.2° W. It consists of fossiliferous sedimentary rock dating from the late Eocene and early Oligocene. It is well known for its vertebrate fossils, hence the name "bone bed". A few invertebrate fossils are also present.

Geology

Reeve's bonebed lies in the Vieja Formation.

Ecology

The University of Texas has a large collection of fossils from Reeve's Bonebed which represent numerous different taxonomic groups. In the following table, the number of specimens of each taxon in the university collection from the bonebed is indicated in the abundance column:

Mammals

OrderFamilyGenus/SpeciesAbundance Notes

Cetartiodactyla
Merycoidodontidae
Merycoidodon
91: common

Cetartiodactyla
Merycoidodontidae
Bathygenys
709: extremely common
hundreds of endocasts

Cetartiodactyla
Leptomerycidae
Hendryomeryx defordi
2: extremely rare

Cetartiodactyla
Leptomerycidae
Leptomeryx
10: rare

Cetartiodactyla
Oromerycidae
Eotylopus reedi
1: extremely rare

Cetartiodactyla
Agriochoeridae
Agriochoerus
15: average abundance

Cetartiodactyla
Protoceratidae
Leptotragulus
1: extremely rare

Cetartiodactyla
Protoceratidae
Heteromeryx defordi
2: extremely rare

Rodentia
Eutypomyidae
Eutypomys inexpectatus
13: average abundance

Rodentia
Ischyromyidae
Pseudotomus johanniculi
1: extremely rare
holotype

Rodentia
Ischyromyidae
Leptotomus
1: extremely rare

Rodentia
Cylindrodontidae
Ardynomys
1: extremely rare

Rodentia
Cylindrodontidae
Cylindrodon fontis
3: extremely rare

Perissodactyla
Tapiridae
Colodon
4: rare

Perissodactyla
Equidae
Mesohippus
11: average abundance

Perissodactyla
Hyracodontidae
Hyracodon primus
1: extremely rare

Perissodactyla
Brontotheriidae
Menodus bakeri
1: extremely rare

Carnivora
Miacoidea
Miacis cognitus
1: extremely rare
holotype

Creodonta
Hyaenodontidae
Hyaenodon
2: extremely rare

Other taxa

Additional fossils to which a genus cannot be assigned include:
  • gastropods
  • testudinata
  • Pholidosteids

    Oreodont braincasts

Reeve's Bonebed is known for the recovery of casts of the brain cavity of oreodonts. When an animal dies and the soft tissues decay, sediments fill the orifices of the bones including the brain case inside the skull. If the bone subsequently falls apart, a cast of the inside of the skull may remain intact. Hundreds of brain casts, mainly from Bathygenys, were recovered from Reeve's Bonebed. These casts have been used to gauge the size of the brain of these animals, as well as the size of the various brain lobes. The physical arrangement of the brain can give clues about the life of the living animal, such as how important smell was to it, as used in CT scans of Tyrannosaurus. Studies involving more than 150 of these endocasts have been performed from the Reeve's Bonebed samples.