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In Search of Clemmys owyheensis In Idaho’s Hagerman Fossil Beds National Monument - Ken Carlsen

 

Copyright © 2003 World Chelonian Trust. All rights reserved


I’ve always had a fascination with geology, rocks and fossils.  Even my turtles and tortoises are like living, walking rocks so it was only a matter of time before becoming interested in fossil turtles and tortoises.  In 2001 I started looking specifically for fossil chelonia of any kind to use in presentations I do several times a year as part of a 2-day Herpetological Workshop through Boise State University.  I acquired a Stylemys nebrascensis fossil, an extinct relative of modern Gopherus tortoises along with a fossil Stylemys egg, and an Anosteria maomingensis from China. 

 

I was born and raised in Idaho and have lived here most of my life.  Idaho only has one species of turtle, the western painted turtle, Chrysemys picta belli, although there was one unverified report from the 19th century of western pond turtles, Actinemys (Clemmys) marmorata. Most people here don’t know we have ‘any’ native turtles.  They have only seen a few species in the pet stores.  I was quite uninformed about fossil chelonia and was unaware that it’s one of the most abundant fossils found.  However, chelonian paleontology is not as glamorous as dinosaurs for ‘some’ people… so it’s not as well studied.  With this newfound knowledge, it dawned on me that the relatively near-by Hagerman Fossil Beds National Monument in southern Idaho may have turtle fossils.

 

I found their website and, indeed, they have found both Trachemys idahoensis and Clemmys owyheensis fossil pieces.  See: Hagerman Fossil Beds National Monument .On this website it explains that the “Hagerman Fossil Beds were deposited during the Pliocene Epoch.  A fluvial (river) and floodplain environment around the edge of ancient Lake Idaho deposited layers of sand, silt and clay at least 600 feet thick.  Layers of sediments have preserved an exquisite world-class assemblage of Pliocene fossils.   The Smithsonian Institution directed fossil excavations in the early 1930's and many other museums and research institutions have conducted research here ever since.”

 

Hagerman Fossil Beds National Monument

 

Due to the paucity of local turtle species, I thought it would be great if they could loan me some fossil turtle pieces for my presentations that were from a local Idaho site.  I was driving across the southern Idaho desert in the fall of 2001 and decided to stop by Hagerman to see what I could learn.  I went into the monument headquarters and told a park ranger what I had in mind and she said that Phil Gensler was at the laboratory packing up for the end of the season.  She called him and he was willing to meet me right then.  I explained to him what I was interested in and found out they cannot loan me any fossils, but he showed me a fossil tentatively identified as Clemmys owyheensis they had been finding pieces of for the last 3 seasons.  He invited me to go along during the 2002 season when they planned to look for more pieces of this same turtle.  He then told me that they were looking for all kinds of modern deceased animals to reduce to bones for comparison to fossil bones they find.  Since I do a lot of chelonian rehab I had a collection of several species from over the years in my freezer.  I told Phil I’d try to locate a deceased Clemmys marmorata, the closest living species to Clemmys owyheensis.  That was a more difficult task than anticipated… but after several months I located a couple deceased animals Phil Spinks had at UC-Davis.  He sent them to me and I took them, along with those animals already in the freezer, to Hagerman on July 10, 2002, the day we were going to continue the search for pieces of this particular Clemmys owyheensis turtle.  It was also about 105ºF that day.

 

Amy Kelly and Josh Samuels crossing the Snake River 

Phil Gensler & Amy Kelly heading up the trail

 

To get to the site, we crossed the Snake River by boat then climbed... maybe 500 feet straight up in loose dirt on a mountain that has had several major land slides in the last 15 years.  Believed to be caused by irrigation erosion from farmer’s fields above the monument.

 

Landslide Area     Tiny Fossils in a Film Can Lid

                               

We began finding fossil bones almost immediately.  It took a while (most of the day for me) to learn to discriminate between fossil material and the surrounding rocks.  One place to find a lot of small amphibian and small mammal fossils is in anthills.  The ants bring them up as they’re clearing their tunnels.  We began to fill film cans with the tiny fossil bones.

 

Phil was missing three peripherals to make a complete carapace from one specific turtle.  This turtle was found 3 seasons before on a plateau.  Apparently the pocket containing the fossil remained undisturbed since the turtle died, even though the surrounding landscape changed considerably over the eons, as all the fossil pieces were found in one place. 

 

Phil Gensler at turtle site   The Three Peripheral found

 

Amazingly, he found 3 peripherals in that pit... and they looked like the correct ones.  Phil appeared to be trying not to get his hopes up that they were from the same turtle but it was obviously not working. 

 

Phil Gensler & Karen Clark record site using GPS technology

Phil Gensler & Amy Kelly filling 5-gallon pails for screening

 

Phil’s team then recorded all the various sites we found fossils that day using GPS technology and then hauled out some 25+ gallons of sediment from the turtle pit which will be screened over the next couple weeks and hopefully will produce more of the skeletal material of the same turtle.  It's really amazing that all those pieces of this one individual turtle remained together over the eons.

 

We also found lots of pieces of Pliocene beaver, frog, fish, camel, more turtle fragments... and what appears to be a cat or dog type knucklebone.  They've been finding pieces of a lion size cat... and the 'dog' appears to be most closely related to hyena.  The area is famous for it's 'horse' fossils, which appear to be most closely related to the modern zebra.

 

As soon as we got back to the workstation Phil pulled out the turtle and the 3 new peripherals were a perfect match!  (The lighter pieces were exposed to sunlight for some time and the darker pieces were not, before being found.)

 

Clemmys owyheensis carapace Clemmys owyheensis plastron

 

He now has a complete carapace of one individual turtle, except for a few small broken fragments, and almost the complete plastron, part of the skull, leg bones and even some claws. 

 

Once the deceased Clemmys marmorata are processed comparisons can begin with this fossil to confirm its identity.  I’ll provide updates as things progress.   Next trip I’m hoping the temperatures will be below 100ºF.


Update on search for Clemmys owyheensis

 

Since the previous article was written a second turtle was found.  Phil Gensler, Nick Peterson, Josh Samuels and I headed to that site on August 27, 2003 but never made it to the turtle.  I had injured my knee so we were taking a less steep, but longer, route when bones of a large saber toothed cat were found on the way.  That took the rest of the day to map out and partially excavate.  On September 11, 2003 Phil, Josh and I headed to the site again.  Phil continued working on the cat site and I was privileged to go on to the turtle site and help finish excavating there.  There was less of this turtle to be found but what was there was in even better shape than the first turtle.

 

Ken Carlsen at second turtle site September 11, 2003

Second Clemmys owyheensis

 


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