U.S. DEPARTMENT OF THE INTERIORBUREAU OF LAND MANAGEMENT
 
Cultural - Mineral Hill Cave
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THE BONES, PART 1 - PRESERVATION, AGE & ORIGIN

Preservation the bones recovered from Mineral Hill Cave are exceptionally well preservedTwo third phalanges (or hooves) of an extinct species of small horse, probably Equus conversidens.  Note the excellent degree of preservation of these specimens.  Based on the dating of other horse bones in Mineral Hill Cave, these two specimens probably are at least 30,000 years old.. The temperature of the cave is a near-constant 40 degrees with greater than 90% humidity. These bones have essentially sat in a refrigerator for thousands of years. The BLM is currently working with Paleoscience, Inc. of Miami, Florida to determine if paleoDNA is preserved in these bones. More information on extracting paleoDNA from ancient bone specimens is available at www.paleoscience.com.

Age

The BLM has contracted with Stafford Research Labs of Boulder, Colorado, and Beta Analytic of Miami, Florida to radiocarbon date individual bone specimens from Mineral Hill Cave. The BLM obtained 55 Accelerator Mass Spectrometry (AMS) dates on 52 different bone specimens recovered throughout the cave. These dates range from 2,000 years ago to >50,000 years ago.Four foot bones of an extinct species of bison, probably Bison antiquus.  The third phalange pictured in the far left of the photo is about 40,000 years old. From left to right: a) third phalange; b) second phalange;c, d) carpals Radiocarbon dating is currently accurate to about 45,000 to 50,000 years ago. Specimens that return dates that are older than 50,000 years are considered "infinite", meaning that we know the specimen is at least 50,000 years old, but we don’t know how much older. Many of the bones date between 30,000 and 45,000 years ago, indicating that this was a relatively active time of bone deposition in the cave.

Bones that are 40,000 years old were found next to bones that are only 8,000 years old, confirming the mixing that has occurred to the deposits, probably by the burrowing activities of marmots. The BLM also submitted a series of charcoal samples from Test Pit 1. Charcoal dated to 600 years ago was found over one meter deep in association with bones that dated to 30,000 years ago, confirming McGuire’s earlier interpretation that the deposits had been thoroughly churned in the past.

Origin

Two subadult bobcat (Lynx rufus) mandibles from Mineral Hill Cave.  Note the small size of the mandibles.  On the specimen on the far left, some of the teeth have not yet fully erupted, including the canine.  A mandible similar to these returned a date of 32,000 years ago.Many of the bones recovered from Mineral Hill Cave were carried into the site by carnivores. Three pieces of evidence support this interpretation. First, a number of subadult carnivore mandibles were found in Chamber 5, most notably young bobcat mandibles. Carnivore remains in general are relatively common. Rich numbers of carnivore bones, and especially the presence of subadult carnivore remains, generally indicates carnivore denning in caves. Second, the vast majority of large mammal bones are represented by lower leg and foot bones.   This bone patterning is typically seen in assemblages in which carnivores scavenge large mammal cacasses and carry the lower limbs and feet to a den site. Third, hundreds of small and large mammal, as well as bird bones, exhibit carnivore tooth punctures, and hundreds of large mammal limb bone shaft fragments were recovered. These latter bones were produced by carnivores chewing and splitting long bones in order to eat the marrow inside the shafts of these bones.  

First phalanges of Large-headed llama (Hemiauchenia macrocephala) and Yesterday's camel (Camelops hesternus).   Like other large mammal remains, lower leg and foot bones dominate the camelid bones identified from Mineral Hill Cave.  The two camel phalanges on the far right are over 40,000 years old.  Left to right: a, b, c (Large-headed llama); d, e (Yesterday's camel)

 Lower leg and foot bones from two species of extinct horse from Mineral Hill Cave.  Lower leg and foot bones dominate the horse bone collection recovered from the cave.  These bones probably were carried into the cave by carnivores that scavenged carcasses nearby.  Some of these bones are from a species of large horse about the size of modern wild mustangs in the Great Basin, probably Equus occidentalis.  The small horse species represented by some of these bones was about 2/3 the size of the larger species,  probably Equus conversidens.  All horse bones have thus far dated between 20,000 and >50,000 years ago. Top row (left to right): metacarpal of small horse; 8 first phalanges; Middle row: 8 second phalanges; Bottom row: 7 third phalanges

 

 

 

 

Unidentified large mammal limb bone fragments from Mineral Hill Cave.  Note the "channeling" caused by carnivore chewing especially seen on the 4th specimen from the left on the top row of the photo.  Also note the high degree of flaking and splitting on the 6th specimen from the left on the top row.  The last two specimens on the bottom row, far right, show extensive polishing from water.  Perhaps these specimens were once effected by the water that periodically flowed into the cave, creating the finely-laminated varve sediments.These latter bones were produced by carnivores chewing and splitting long bones in order to eat the marrow inside the shafts of these bones.

 The Mineral Hill Cave collection also contains hundreds of intact bones of smaller animals such as bats, lizards, mice, woodrats, and marmots which may have simply died naturally inside the cave. Two yellow-bellied marmot (Marmota flaviventris) mandibles from Mineral Hill Cave.  Unlike the large mammals, marmots are well represented by all skeletal parts of the body.  In addition, most of the marmot bones are complete, although some do show evidence of carnivore or raptor (birds of prey) puncture marks.  This indicates that marmots once actively lived (and died) inside the cave.  Marmots are the likely culprits of the extensive disturbance caused to the cave sediments in the past.  Many marmot burrows, full of marmot bones, were seen during the excavations.

 

 

 

 

 

 


History of Research at Mineral Hill Cave
To the Lab ....
The Bones, Part 2 - Species Present
More on Mineral Hill Cave - Workshop Paper 
Mineral Hill Cave [Monograph]

Mineral Hill Cave Introduction Home Page

 


 
Last updated: 12-14-2007