Reeve's Bonebed

Reeve's bone bed 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", but some 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. In the following table, the number of specimens in the university collection is shown in the abundance column^[1]:

Mammals

Order	Family	Genus/Species	Abundance (?/870)	Notes
Cetartiodactyla	Merycoidodontidae	Merycoidodon	91: midly common
	Merycoidodontidae	Bathygenys	709: extremely common	hundreds of endocasts (see below)
	Leptomerycidae	Hendryomeryx defordi	2: extremely rare
	Leptomerycidae	Leptomeryx	10: rare
	Oromerycidae	Eotylopus reedi	1: extremely rare
	Agriochoeridae	Agriochoerus	15: average abundance
	Protoceratidae	Leptotragulus	1: extremely rare
	Protoceratidae	Heteromeryx defordi	2: extremely rare
Rodentia	Eutypomyidae	Eutypomys inexpectatus	13: average abundance
	Ischyromyidae	Pseudotomus johanniculi	1: extremely rare	holotype
	Ischyromyidae	Leptotomus	1: extremely rare
	Cylindrodontidae	Ardynomys	1: extremely rare
	Cylindrodontidae	Cylindrodon fontis	3: extremely rare
Perissodactyla	Tapiridae	Colodon	4: rare
	Equidae	Mesohippus	11: average abundance
	Hyracodontidae	Hyracodon primus	1: extremely rare
	Brontotheriidae	Menodus bakeri	1: extremely rare
Carnivora	Miacoidea	Miacis cognitus	1: extremely rare	holotype
Creodonta	Hyaenodontidae	Hyaenodon	2: extremely rare

For fossils of which an exact genus cannot be assigned, there have been discovered...

gastropods

testudinids

Pholidosteids

Oreodont Braincasts

Reeves bonebed is known for the recovery of casts of the brain cavity of oreodonts called endocasts.^[2] When and animal dies and the soft tissues decay, sediments fill the orifices left, including the brain case. If the bone falls apart, the fossil that used to be housed on the inside of the skull can remain. Hundreds of brain casts, mainly from Bathygenys, were recovered from Reeves bonebed and have been used to gauge the size of the brain as well as the size of the lobes. Physical arrangement of the brain can lead to 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 Reeves bonebed samples.^[3]

References

^ University of Texas, Austin. Bonebed&county=&state=&specid=&geol_form=&epoch=&site_no=&showimage=&geog=&country=&others=&geol=&epoch=&period=&age=&era=&strat=&formation=&group=&horizon=&member=&sorted_by= "Reeves bonebed". {{cite web}}: Check |url= value (help)
^ "Oreodont braincasts".
^ Macrini, Thomas E. "Description of a Digital Cranial Endocast of Bathygenys reevesi (Merycoidodontidae; Oreodontoidea) and Implications for Apomorphy-Based Diagnosis of Isolated, Natural Endocasts".

[1] University of Texas, Austin. Bonebed&county=&state=&specid=&geol_form=&epoch=&site_no=&showimage=&geog=&country=&others=&geol=&epoch=&period=&age=&era=&strat=&formation=&group=&horizon=&member=&sorted_by= "Reeves bonebed". {{cite web}}: Check |url= value (help)

[2] "Oreodont braincasts".

[3] Macrini, Thomas E. "Description of a Digital Cranial Endocast of Bathygenys reevesi (Merycoidodontidae; Oreodontoidea) and Implications for Apomorphy-Based Diagnosis of Isolated, Natural Endocasts".

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