Zoo Cave, Taney County, Missouri

When I was a kid looking up information in an encyclopedia for a school project, I’d always get sidetracked and find something interesting while flipping the pages to the intended subject.    The same holds true today when I’m researching material for my blog, especially thanks to the thousands of  results produced by a typical internet query.  Probably half my blog articles originated from stuff I came across while looking up other stuff.  A few weeks ago, while researching my blog article about Pleistocene megafauna in northeastern North America, I reached for Bjorn Kurten’s Pleistocene Mammals of North America on my book shelf.  I was looking for Pleistocene-aged fossils sites in New York and New Jersey.  Much to my surprise, Kurten didn’t list any for those states.  Both states have lots of fossil sites but evidentally they were poorly documented in the scientific literature at the time this book was published in 1980.  However, as I was thumbing through the alphabetical order of the states, I was intrigued by a paragraph about Zoo Cave in southwestern Missouri.  Kurten stated the evidence found at this site suggested 2 climatic stages–a warm dry and a cool moist.  Kurten cited an obscure cave journal article published in 1975 as his source.  I was able to obtain a back copy of this journal for $10.

Taney County, Missouri where Zoo Cave is located.

Upon reading this article, I discovered the conclusion made by the original authors and repeated by Kurten was a wild overreach.  The majority of the fossil organisms found in this cave preferred cool moist environments, temperate climates, or are not restricted to any specific habitat.  The only mammalian species excavated here that preferred warm environments was the beautiful armadillo (Dasypus bellus).  However, since this article was published, fossils of this species have been found as far north as Indiana.  Modern armadillos found in North America can survive in cool climates as long as the ground isn’t frozen solid for long periods of time.  They stay in deep underground burrows during spells of sub-freezing temperatures and emerge on warm days to dig for worms and beetle grubs which are in the soil year round.  I can’t believe the authors of the study made their sweeping interpetation based on such flimsy evidence.  They assumed the occurrence of a warm dry climate phase based on a single species.

Zoo Cave did hold the remains of at least 81 flat-headed peccaries (Platygonnus compressus).  The cave was not a natural trap.  Instead, many generations of peccary herds used the cave as a shelter.  The green fractures found on many of the peccary bones probably resulted from peccaries trampling over their dead brethren.

New Pictures 063

The top photo from the below referenced journal shows green fractures of peccary bones.  There’s no evidence they were gnawed upon.  Herds of peccaries probably just trampled over bodies of their kin while staying in the cave.  The bottom photo is probably of a natural artifact, not a human made scraper.

A small dire wolf skeleton was also found in the cave.  Eight species of smaller animals that no longer occur this far south or east had a range that extended to this cave during the Ice Age.  They include the fox snake, arctic shrew, masked shrew, southern bog lemming, red backed vole, meadow vole, porcupine, and plains pocket gopher.

Fox Snake

Fox snake (either Elaphe vulpina or E. gloydi).  Fossils of this species were found in Zoo Cave.  It is a type of rat snake that no longer ranges this far south–evidence of cooler climate at the time of deposition.

The spectrum of animals found here suggests a local Ice Age environment that consisted of a mixed boreal and hardwood forest with some prairie openings, not unlike that found in modern day southern Minnesota, but it likely has no exact modern analogue. Fossil evidence of elk, fox squirrel, woodchuck, beaver, red fox, black bear, coyote, and raccoon was excavated from the cave.  The fox snake and 6-lined race runners preferred the prairie openings, but most of the species are most often found in temperate woodlands.

Zoo Cave is located in Mark Twain National Forest where an oak-hickory climax forest grows on good soils and cedar glades are found on poor soils.  The cave was discovered by 2 brothers over 40 years ago.  The cave passages total 1100 feet long.  The authors of the article found fossils in just about every area of the cave but intensively excavated just a part named “bone passage,” leaving the rest for future paleontologists.   As far as I can determine from available literature, this cave is little known and would be worth re-examination.

There is an interesting table in the journal article about Zoo Cave comparing northern and western faunal elements recovered from this cave with those found in 2 other Missouri Caves. Fossils of snowshoe hares and red squirrels were found in Bat Cave and Crankshaft Cave.  These 2 species no longer occur in this state.  Porcupine fossils  were also found in Crankshaft Cave, but fisher fossils were found in Bat Cave.  The latter preys upon porcupines.  Fossils of grasshopper mice, a western species, were  found in Crankshaft Cave.  The table lists a kit fox fossil as being recovered from Crankshaft Cave, but these remains probably represents the swift fox, a species also found west of Missouri today.

Swift fox (Vulpes velox) remains were found in Crankshaft Cave, Missouri.  This species no longer occurs this far east.  Its presence is evidence of an eastward extension of prairie habitat during the Ice Age.

Fossil sites as far east as Ohio, Kentucky, Georgia, and Florida provide evidence of an eastern extension of prairie fauna during the Ice Age.  There is a striking resemblance between fossils found in Missouri caves with those found in Welch Cave, Kentucky, indicating a similar type of environment covered a large swath of the midwest during the Ice Age.  (See https://markgelbart.wordpress.com/2012/09/12/the-kentucky-bluegrass-country/).

Reference:

Hood, Clark; and Oscar Hawksley

“A Pleistocene Fauna from Zoo Cave, Taney County, Missouri”

Missouri Speleology 15 (1) 1975

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