Peccary Cave in Arkansas

Perhaps the best site for Pleistocene fossils in Arkansas is Peccary Cave located in Newton County.  The site was first excavated in 1960s, and a follow-up expedition prospected for fossils again in the early 1990s.  The fossil remains of at least 51 species of mammals have been found here. 4000 specimens of a minimum of 64 individual flat-headed peccaries (Platygonus compressus) were discovered in the cave, hence the name.  The bones of other extinct species excavated from the cave include mammoth, mastodon, bison (Bison antiquus), stag-moose, helmeted musk-ox, tapir, beautiful armadillo, and dire wolf.  There are also remains of extralimital species found here that no longer occur in the region–grizzly bear, pine marten, porcupine, heather vole, and numerous other rodents and insectivores of northern affinities.  Plenty of species still found in the region are represented in the cave as well such as beaver, otter, muskrat, raccoon, coyote, gray fox, opossum, and either mule or white-tailed deer. Reptile and amphibian specimens have been excavated from the cave along with a few human-made artifacts of unknown cultural origin.

Map of Arkansas highlighting Newton County

Newton County, location of Peccary Cave.  

Image result for Platygonus compressus

Illustration of the flat-headed peccary.  Peccaries didn’t use Peccary Cave as a den.  Instead, they either fell inside or their bones were washed into the cave when the nearby creek flooded.  Birds of prey dropped or defecated smaller animals into the cave from overhanging trees.

The fossils represent several different climate phases.  The lowest level contains fossils over 22,000 calendar years BP, a climate phase that includes a weak interstadial and the following early glacial maximum.  Mixed Ice Age woodlands of spruce, pine, and hardwoods interspersed with prairies predominated.  7 different species of squirrels lived in the region then, showing how many diverse habitats occurred here.  Red squirrels and least chipmunks, now absent from the region, preferred spruce forests; gray squirrels, fox squirrels, and southern flying squirrels occur in temperate hardwood forests; woodchucks like meadows; and 13-lined ground squirrels require tree-less plains.  The author of the study discussed below thinks the following glacial maximum caused the entire Missouri Plateau to become inhospitable desert because there are few fossils from the site, dating to between 21,000 calendar years ago-15,000 calendar years BP.  Undoubtedly, the region became more arid during this climate phase, and desert scrub grassland likely predominated, but I think there are alternative explanations for the lack of fossils during this time period here: a) the cave entrance may have become closed and/or b) the barren landscape allowed animals to see the trap entrance and avoid it whereas before it was hidden by thick vegetation and animals frequently fell inside.  Without overhanging limbs there was no perch for birds of prey to drop of defecate the remains of their meals.  Moreover, the nearby creek dried up, so there were no floods to wash fossils into the cave.

The upper level of sediment represents a warm dry interstadial post 15,000 calendar years BP when the region was dominated by grassland.  Bison fossils appear during this phase, and toad fossils outnumber frog bones.  Toads can survive better than frogs in more arid climates.

Kurt Wilson wrote his PHD thesis about the peccary and dire wolf bones found in Peccary Cave.  His paper has interesting information, but it is incompletely researched, and his conclusions are logically flawed.  He believes flat-headed peccaries were always an uncommon species.  Part of his reason for this assertion is based on his incorrect observation that “the southeast is virtually devoid of records (of flat-headed peccaries), except for a dozen localities in Florida.”  Wilson is unaware of 2 sites in north Georgia (Yarbrough Cave and Ladds) and 1 site in coastal South Carolina where fossil remains of flat-headed peccaries have been found.  It is also illogical to assume a species was absent from a region based on its absence in the fossil record.  Large areas of the southeast are devoid of fossils because the local geology is not conducive to fossil preservation, not because animals didn’t live there in the past.

Wilson concludes flat-headed peccaries became extinct due to climate change based on 4 lines of evidence that are easily debunked.

1. He dismisses overhunting by humans as a cause of flat-headed peccary extinction when he regurgitates the tired old claim of Meltzer and Grayson (an archaeologist and anthropologist…not paleoecologists) that there isn’t enough archaeological evidence of human interaction (kill sites) with this species.  I consider this reasoning absurd in the extreme.  99.999…etc% of animals that ever lived on earth left no fossil evidence whatsoever.  It has always seemed unreasonable to me to expect the remains of the final populations of a species that overlapped with man for less than 2000 years to be preserved in the fossil record.  The chances of this happening are tiny.  I’ve noticed Grayson’s recent book published in 2016 is frequently being cited in new papers about Pleistocene vertebrates.  Grayson was blatantly dishonest in this book in the way he characterized a study that rules out climate change models of extinction.  (See: https://markgelbart.wordpress.com/2017/01/23/donald-graysons-disingenous-case-against-overkill/ ) Grayson lied and he knows he lied.

2. Wilson assumes flat-headed peccaries became extinct in this region about 22,000 calendar years BP because their remains don’t occur in cave sediment after this date.  (When Wilson writes of extinction in his paper he means regional disappearance or extirpation because he’s aware terminal dates for this species in other regions are 11,000 calendar years ago.  Nevertheless, he clumsily never makes this distinction in his paper.)  He asserts peccaries became extinct here because the climate became too arid for them.  Again, he is basing his assertion on the dubious assumption that the absence of evidence is evidence of absence.  I think flat-headed peccaries were probably even more abundant during the arid climate phase because they were anatomically well-adapted to dry dusty environments.  Flat-headed peccaries had extensive structures in their nasal passages that helped filter dust.  Wilson must be unaware there are at least 9 fossil sites where herds of flat-headed peccaries were buried during sandstorms.  (See: https://markgelbart.wordpress.com/2013/03/10/when-sand-dunes-buried-herds-of-flat-headed-peccaries/ ) This suggests they were common in desert environments.  Flat-headed peccaries may have avoided falling in Peccary Cave after 22,000 calendar years BP because the area around the entrance to the cave was barren and not hidden by vegetation.  None happened to fall in the cave after this date, but that doesn’t mean they didn’t still occur in the region.  Other fossil sites in the region yield the remains of horses, but not a single horse fossil has been found in Peccary Cave.  Horses were likely another abundant species in the region that just happened to never fall in or enter Peccary Cave.

3. Wilson did a stable isotope analysis of 2 flat-headed peccary teeth and concluded they fed upon just a few leguminous plant species, so they became extinct when these limited number of plant species disappeared from the region.  I don’t believe the entire dietary breadth of a species can be determined from such a small sample size.  Moreover, 1 study suggests stable isotope analysis is not at all reliable.  (See: https://markgelbart.wordpress.com/2016/06/24/trust-the-coprolites-not-the-stable-isotope-analysis/ )  Scientists compared the results of a stable isotope analysis of moa bones with actual fossil droppings.  The stable isotope analysis was wrong.  Flat-headed peccary teeth were built to eat grass and tough vegetation.  A species that survived millions of years of climate change didn’t exclusively feed upon just a few species of leguminous plants.

4. Wilson asserts flat-headed peccaries were uncommon and thus vulnerable to extinction.  However, a new genetic study of 12 flat-headed peccary individuals from Sheridan Cave, Ohio, dating to just before their extinction revealed populations of this species were diverse and expanding.  This suggests flat-headed peccaries were common, adaptable, and had a wide geographical distribution until the species’ demise.

Peccary Cave has yielded a wealth of information for paleoecologists, and I’m shocked at how little research has been published about this site.  I’ve been able to find about half a dozen research papers.  There hasn’t been a scientific excavation of the site since 1993, though amateurs are currently pillaging it.  Most of the specimens from this site have not yet been described in the scientific literature, and they are not listed on the paleobiology database. An early report of the site mentions the existence of peccary “droppings.”  Yet, nobody has studied the coprolites (please email me if I’m wrong)–an outrageous oversight.  We could actually find out what flat-headed peccaries ate, instead of guessing based on stable isotope analysis.  I’m not sure the coprolites were even collected and stored in a museum.  There should be hundreds of published papers about this site, not just a paltry 6.  I’ve come across other understudied fossil sites and collections in my research, but this site might possible be the most underappreciated.

References:

Bell, Kenneth; and Lee Davis

“Sinkhole Excavations in Peccary Cave, Newton County, Arkansas”

Arkansas Academy of Science 47(30) 1993

Davis, Lee

“Biostratigraphy of Peccary Cave, Newton, County, Arkansas”

Arkansas Academy of Science 1969

Perry, Tahlia; et. al.

“Ancient DNA Analysis of the Extinct North American Flat-headed Peccary (Platygonus compressus)”

Molecular Phylogenetics and Evolution 2017

Wilson, Kurt

“Late Pleistocene Extinction of the Flat-headed Peccary on the Ozark Plateau: Paleozoological Insights from Peccary Cave”

Iowa State Graduate Thesis 2017

 

 

 

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One Response to “Peccary Cave in Arkansas”

  1. ina puustinen-westerholm Says:

    Hey..grab your coprolite collections bags, a few other educated outdoor-history detective sorts..and go camp at the site..before the winter weathers arrive. If that all..was avail. around our area..i’d be there..in a heartbeat. That is with being 81..in a couple months..and the right knee..sweating out a spike/bone glue..and new metal knee. 😉 New study materials..worth it!

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