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Montbrook volunteer dig March 2019


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For several years now we've been fortunate enough to be able to take part in volunteer digs with the Florida Museum of Natural History (FLMNH), University of Florida (Gainesville). The site was discovered at the end of 2015 and we've been participating during the dig seasons (the drier cooler part of the year) since 2016. The site is on private property but the landowner is very enlightened and understands the importance of this site which gives a rare glimpse into the Hemphillian North American Land Mammal Age (NALMA) period dating around 5.0-5.5 mya. The owner has been very supportive of letting the museum (and its staff, students, and volunteers) onto his property and even helps quite frequently using his excavators to clear the overburden and manage the site for drainage. You can learn more about the site and the finds here:

 

https://www.floridamuseum.ufl.edu/montbrook/

 

We were previously out to the site last November digging in the main pit. Tammy found some nice gomphothere bones and I dug a rather sterile sandy grid square but happened upon a cache of over a dozen associated gator osteoderms--both the larger circular ones from the back and the elongated ones from the border of the tail. The site is closing for the season at the end of March so we found some time in our schedule to make the trip north for a final dig before the site gets tarped for the summer.

 

We had planned on heading up on Sunday evening for the dig on Monday through Wednesday but it is nice to have flexibility in our schedule. Tammy and I are looking to relocate to the Gainesville area so that I can volunteer more with the FLMNH (and attend these digs more often). :) We've been looking at houses in the Gainesville area for several months now and periodically make the 5 hour drive from South Florida to see properties of interest. Late Thursday a property that looked interesting popped-up. We decided to modify our schedule to drive up early Friday morning instead. Unfortunately, (as is often the case) the house and property looked better online than in person. We visited a few other newer properties in the area and then decided to head up to Jacksonville (about a 1.5 hour drive) to stay with friends over the weekend. Hotels tend to bump up their rates over the weekends--We've seen hotel rates triple in Gainesville when the alumni return for Florida Gators home football games. :blink:

 

We spent an enjoyable weekend with our friends up in JAX and headed back down on Sunday (getting in an open house viewing before checking into our hotel in Gainesville). We were ready for our 3-day dig at Montbrook starting the next morning.

 

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Dig Day 1

 

When we arrived on the site we were surprised to find that most of the digging had relocated to a new section to the west of the main dig site. This was a site that was starting to be cleared last time we were on site in November. The property owner, Eddie, was using his excavator to remove a large section of overburden adjacent to the main dig pit. This extension was important for the dig since our dry season has been AWOL this year and we've had way more than our share of unseasonable rain throughout the supposed "dry season". A new section of 1m x 1m grid squares had been plotted out and the corners marked with small wire flags with orange plastic flags.

 

This was Monday so the site was being managed by Art Poyer, Collections Scientist from the FLMNH and Cindy Lockner, a very experienced volunteer who has worked this site more than any other volunteer. We've known Cindy and Art for several years and so it is always good to see old friends in the field. We were free to find some grid squared in which to work and so we found some spots that gave us a bit of space from the other volunteers and got to work removing the layered matrix of soft sugar sand, harder lithified sand, and clay. Excavation proceeds by digging with a (fairly worn-down) flat-blade screwdriver and dental picks (for detailed work around fossils). Small trowels are available to help scoop up the loose matrix into the ubiquitous pails for matrix transport--old cat litter containers. I've found that it is easier on the spine to fill a pair of buckets (not too full) and, with balanced weight, walk them up out of the pit to the area where we dump the matrix. We did a lot of digging and a lot of lugging of matrix up that hill over the next couple of days.

 

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Sometime during the previous week someone had uncovered a nice gomphothere radio-ulna (the fused lower bones of the front leg). This find had been pedestalled and was awaiting its plaster jacket.

 

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At the conclusion of the first day Tammy had found a few bones for her bone bag but the square I chose was pretty sterile. Though it was adjacent to a large gomphothere pelvis that was exposed and in need of a jacket. The surrounding squares had to be lowered quite a bit before this large item could be jacketed and removed. I decided to help work toward this end by leveling off and squaring my chosen grid square. There is something about being a computer programmer with a touch of OCD that causes my squares seem like they were laser cut by day's end. I've got something of a reputation for doing this--so much so that people can easily identify grid squares that I've previously dug. ;) Neat or not, this square was virtually sterile sandy matrix and it only revealed one small bone fragment (likely gomphothere) near the bottom of where I was digging. It was a light and disappointing bone bag for my first day. We drove back to our hotel rehydrating and downing fistfuls of ibuprofen to make sure we'd be able to move the next day after sitting folded-up in our squares all day.

 

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Dig Day 2

 

We arrived a few minutes later than expected at the dig site this morning. Our usual route to the site from Gainesville was blocked by a semi-trick driver who had chosen to try to make a sharp left turn and had driven far enough off the road to get the front of the truck stuck quite well in the soft ground alongside the road. At this point the truck's trailer had created an efficient blockade against traffic passing in either lane. We doubled back and found an alternate route with the help of Tammy's iPad passing through various small country roads in northern Florida that we've never seen and likely never will again.

 

On Tuesdays the site manager is Dr. Richard Hulbert, Collections Manager for the FLMNH and well known here for managing the Florida Fossil Permits and answering ID questions on our finds throughout Florida. Jason Bourque, Preparator for the FLMNH and expert in the order Testudines (turtles and tortoises) was on hand as well. Montbrook is exceedingly rich in turtle fossils and Jason has enjoyed a real motherlode of turtle specimens from this site. There are so many nicely preserved turtle shells (carapace and plastron complete and articulated) that the museum has had to become picky about turtle specimens. If a turtle shell is uncovered, it must be very nicely complete and intact to elicit a jacket. Anything less than virtually complete ends up getting consolidated with Butvar B-72 thermoplastic resin glue and removed in chunks. Isolated shell pieces or turtle bones are simply tossed into the big plastic bone bag that holds your finds for the day.

 

When we got there Dr. Hulbert was giving his introduction to Montbrook for a couple of first-time volunteers in the main pit. Part of the group was still digging on a productive portion of this main dig area that was above the groundwater level. Several heavy rains during the supposed dry season had brought up the water table and had melted the nice pattern of grid squares in this section. If they want to dig this section again next season (hopefully drier) they'll have to spend some time resetting the grid pattern and mucking out a lot of sloughed muddy sand that has filled in the lower elevations of this site.

 

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Tammy moved to a new grid square and soon had some success with part of a gator pelvis that was just under the top layer of matrix in the corner of her square. The previous digger had stopped just short of finding this item. New matrix is usually a bit damp and cool from the moisture in the sand but once exposed for some time it tends to dry and harden. The hard cap on the top can be like digging through concrete but luckily the site has a source of water--a large tank at ground level with a system of hoses to help soften up some of the hard-baked matrix areas. Tammy had to wet down the area after exposing a small portion of the bone. It came out quite cleanly with only a single break leaving the specimen in to easily rejoinable pieces.

 

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Dr. Hulbert decided that the radio-ulna in the middle of the upper site needed to be jacketed and so he set off to do just that. With some strips of burlap and a bucket of plaster he was able to protect this specimen so we were more freely able to work around it. He started by giving it a light spray so that he could straighten up the sides of the pedestal and so that the dry matrix wouldn't pull the moisture from the plaster too quickly. He packed some clean sand on top of the exposed bone to cushion it during jacketing and then got plastered. :P The completed jacket contains a label with the jacket's serial number and a description of what it contains. The label is attached upside down as the jacket will be flipped and stored inverted. After completing this jacket Richard enlisted some others to detach, flip and carry out a large jacket from the lower section.

 

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For me, the second day finished much as the first did. I worked another adjoining grid square to the large gomph pelvis (seen partially protected by an empty sandbag in the photo below). I took this square down well over a foot in depth to match the lower level that had been excavated in front of the pelvis. My neatly excavated square is evident in the photo but I neglected to photography my even more paltry bone bag for the second day. It contained a single (relatively common) catfish spine--and not even a very good specimen as it was river tumbled and well worn down. Another effective day toward the end result of freeing the pelvis but not notable for finds. Some squares can be quite hit or miss but excellent and rare finds have turned up in the most sterile and unpromising of squares so you just have to dig them to know what they contain.

 

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Dig Day 3

 

Tammy moved to a square in which a small gomphothere bone had been exposed along the edge and worked that square to great success all day. As this was Wednesday, Cindy Lockner was back as site manager. She had started to create more of a trench around the opposite side of the gomph pelvis from where I had worked the previous day. I joined her to continue this trench all the way around so that the pelvis would soon meet its jacket.

 

It wasn't long before Tammy started spotting finds like a gomph bone (likely a carpal or metacarpal) with some smaller bones (likely gator or turtle) stuck in the matrix.

 

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She had another nice bone that appeared to be an epiphyseal growth plate from a longer bone given that one side was smooth an the other showing the rugged texture characteristic of these bones.

 

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She also came upon what looks like it might be a related small sesamoid bone from the foot--small is a relative term when talking about gomphothere bones.

 

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The trench I was continuing around the pelvis seemed like it was going to be a replay of the last two days. Much of the matrix that I was digging through was a very soft sugar sand that is like digging through a sand castle on a beach with a screwdriver. I did hit some more coarse yellower sand that produced a larger fish vertebra and a few small unremarkable items. About halfway through this trenching operation, my screwdriver detected a more solid target while digging through the soft sand. After a bit of probing around I could see that a larger bone was appearing. After two days of digging sterile sandy matrix I finally had something fun to excavate.

 

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While digging around this bone (which I originally thought might be a rib) to find its extent I happened upon a gomph toe bone (possibly a carpal) of my own hiding in the sand.

 

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About this time Tammy showed me that the small nondescript knob of bone that she was digging around in her square turned out to be attached to something much larger. As she worked on this to uncover more, it was revealed to be the end of a gomphothere femur.  It was getting close to the end of the day and there was no way she'd be able to see this entire bone before we left so Tammy decided that we should extend this volunteer dig by a day and that we'd just have to drive back to Gainesville and check back into the hotel so we could dedicate another day to the dig. I hope I'm making some of you married diggers jealous at this point as I did not even need to coerce my spouse to continue our fossil hunting fun. :)

 

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I continued to work around my bone which by this time was obviously not a rib bone which it resembled near the flat middle area but now looked to likely be a fibula from the lower hind leg of the gomphothere. I cleaned up the pedestal I had made and covered the exposed bone on the surface with a couple of empty sand bags before the site was tarped for the night.

 

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Dig Day 4 (BONUS)

 

Dr. Hulbert was back on Thursday as the site manager and he was there with a smaller group at the lower dig site. Luckily, this day was relatively lightly populated so that it was not a problem extending our dig by a day. The rest of the group worked some nice specimens down in the lower area while Tammy and I had the upper site all to ourselves. I thought maybe we could get to jacketing the fibula I had uncovered the previous day but Dr. Hulbert said they would leave that for fieldwork practice for one of the paleo classes coming on Friday.  Instead, I joined Tammy on focusing on uncovering and creating the pedestal for her gomph femur. We had a lot of matrix to remove from the surrounding area so that there would be room to create the plaster jacket for this specimen. We were digging in 4 separate grid squares as this large bone was found in the "four corners area" with the flag marking the corner point right in the middle of the area to be jacketed. Since we'd be excavating 4 different squares we needed separate bone bags with labels indicating where any smaller finds were located in the overall grid. This area had more fossils than where I'd been digging the first couple of days and we had interesting specimens to put in all 4 of our bone bags for the day. You can see the large jacket from the radio-ulna that was jacketed earlier in some of these photos. It is possible that our femur (and several of the toe bones) may be associated with this.

 

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Tammy pulled a nice gator osteoderm from the are she was working. It was the first I'd seen on this trip--they are usually more common at the site but our area seemed to be more gomphothere themed than gator or turtle. I came across a thin gator bone and was able to recognize a small gator vert when I pulled it out of the wall as I've now seen a good number of these.

 

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We kept on our trenching efforts which required us to take down quite a bit of material from the wall behind the pedestal we were outlining. We bagged any smaller specimens we found along the way and continued to work toward the goal of finishing the trenching for the pedestal before we left for the day. We made steady progress and walked a lot of buckets of loose matrix up the hill to dump.

 

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While making the trench around the hip end of the femur in the back of our excavation, I happened upon a nice gomph metacarpal toe bone. A few minutes later another hard item signaled its presence in the soft sand with resistance from my probing screwdriver that was widening the trench channel around the pedestal. Another likely related toe bone appeared in the wall shortly after which I removed and gave to Tammy to clean-up while I worked steadily to complete the trench by quitting time.

 

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I cleaned up the site and finished off the trench with Tammy taking over the job of dumping my buckets of matrix while I refilled them. With cooperation and a long day's work we had completed our mission to uncover the entire extent of the femur and make the pedestal and surrounding trench so the bone could be jacketed by the paleo class the next day. We consolidated the other end of the bone with some additional B-72 and managed to pose for a photo with our femur before protecting the bone with some empty sand bags so the site could be tarped again and await the attention of Friday's class.

 

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This visit to Montbrook started slow and gave up finds grudgingly at first but continuing effort paid off in the end. Gomphothere bones were much less common in the lower dig area (mostly being found at the deeper levels called the "gomph layer"). We certainly had our fill of nice gomphothere bones on this trip--both smaller nicely preserved foot bones as well as some nice larger specimens that should by this time be jacketed, inventoried, and sitting in storage with hundreds of other jackets awaiting the attention of volunteers in the prep lab. As soon as we find our new house in Gainesville that volunteer could very well be me. ;)

 

Thanks again for making it to the end of another patent pending highly verbose and heavily illustrated trip report. :P

 

 

Cheers.

 

-Ken

 

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What a great report, Ken! I really enjoyed reading this and looking over the pics. During our hunt together, you told me a bit about this site. Now this kind of puts a face to it. I am glad you and Tammy enjoyed yourselves.:dinothumb:

 

Dave

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Sounds like a lot of fun. Y'all did good on the gomph bones this time.

Thanks for sharing the visit again.

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DPS Ammonite

Thanks Ken @digit for the nice write up.

 

What is the story behind the site’s accumulation of fossils? Why are so many at the site; was there a sudden catastrophic event such as a flood or hurricane?

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Tidgy's Dad

Excellent report! 

Most enjoyable and informative.:)

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Wow, Ken - what an interesting few days for you and Tammy (especially Tammy, at least at the very start of the trip :P)!!!  Congrats on the outstanding finds!!!

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8 hours ago, DPS Ammonite said:

What is the story behind the site’s accumulation of fossils? Why are so many at the site; was there a sudden catastrophic event such as a flood or hurricane?

From what they've been able to infer by looking at taphonomic clues at the site is that this fossil hoard appears to be a coastal river system. It is unclear if this very spot represents a bend or some sort of sandbar that might have accumulated such a wealth of bones or if this is simply part of a large river that was accumulating animal remains along its length. The full extent of the site has not yet been determined. While there are some spots that contain more or less fossil material and certain layers like the "Turtle Death Zone" that are especially rich in one type of fossil, they have not yet reached an edge and so the site still holds some mysteries.

 

Another dig site owned and managed by the FLMNH is called Thomas Farm (from the previous owners). The fossils from that site are approximately 18 myo (Burdigalian in the early Miocene). They know from the taphonomy of that site that it was a karstic cave chamber in the Eocene limestone rock with a sinkhole-like opening in the center that accumulated sediments and animal remains that either stumbled into the trap or were swept in during floods (there appears to have been a river nearby that may have breached its banks during heavy storms). They have reached the edges of that site and they can tell from the angle of the matrix layers approximately where the opening was. The alternating layers containing more sand or clay form a conical structure just like the sand accumulates in the lower chamber of an hourglass.

 

https://www.floridamuseum.ufl.edu/index.php/thomasfarm/home/

 

Montbrook has varying layers of fine soft sugar sand that likely were laid down during normal river flow. There are various layers where more gritty sand is capped with finer clay layers which would indicate a flood (hurricane?) that eroded older material out of banks upstream where the more coarse material settled out first followed by the finer sands and silts at the end of this pulse of water. We often find reworked shark teeth and other marine fossils in this very recognizable layer named 2A. They have taken samples of matrix from different layers back to the lab for screenwashing. The softer sugar sands are mostly devoid of micro-fossils as are the layers that are more silt/clay bound. The 2A is often so packed with micro-fossils that you can spot tiny shark, ray, and fish teeth while digging through the layer. When a layer of this more gritty matrix is exposed in a square the matrix is bagged, labeled, and trucked back to the lab for later screenwashing. A large number of micro-fossils have come from these micro-matrix layers and a number of species of rodents, birds, fishes, reptiles and amphibians were added to the faunal list based on their micro-fossils.

 

https://www.floridamuseum.ufl.edu/montbrook/about-montbrook/

 

It's a really interesting (and scientifically important) site so it is great to be able to help the museum explore and collect valuable fossil material from this rare glimpse into Florida from this time period of which very little is known. Of course, we all want to be the one who discovers a rare species like the Giant Otter or one of the felids like the early Small Saber-toothed Cat or the recent Lynx-like Cat but every bone bag and jacket and the end of the day are new pieces to the puzzle.

 

 

Cheers.

 

-Ken

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Wow. Great on the landowner for being so accommodating. Looks like a lot of fun.

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Really nice report, Ken. I've spent several days at Montbrook during the past couple of seasons and really enjoyed working there. -- George

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Looks like a lot of fun Ken, great pics as always :fistbump:

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Shellseeker

Wow Ken. Very nice and love the level of detail.:fistbump:. I have a bunch of photos from my trip also and even a few from the Lab preparers.  You should craft this into a book or at least a pamphlet:  Tales of a Montbrook volunteer

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I have wondered what happened to that other tusk....

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4 minutes ago, Shellseeker said:

You should craft this into a book or at least a pamphlet:  Tales of a Montbrook volunteer

Hah! I read that wrong the first time and thought someone had already created this in blog or PDF form. I was looking forward to reading it. :P For now, I think I'll limit my publishing to War and Peace length trip reports here on the forum. When I finally get translocated up to Gainesville and I'm able to spend significantly more time volunteering, I may be moved to chronicle my exploits in some sort of blog form for the FLMNH or possibly just keep a running thread going here with updates as interesting events unfold.

 

4 minutes ago, Shellseeker said:

I have wondered what happened to that other tusk....

They've found isolated tusks (both upper and lower as this beastie had two sets) at the site. I'm surprised that this mandible had at least one still attached.

 

 

Cheers.

 

-Ken

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DeepTimeIsotopes

Wow, I don’t know about you but this is what I imagined being a paleontologist looks like when I was a kid. Nice report!

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It's fun to play paleontologist for a day (or 4). Though you don't get to keep any of the fossils you find, you can take all the photos you want (as you can see). You get to dig on a very fossil rich site and all of the finds go to the museum and you get to claim mild fame as your specimens are logged into the collections database with you listed as the original collector. It's a great time and a spectacular opportunity to be able to assist digging on a very important fossil site providing a rare glimpse into the fauna of Florida (and the southeastern US) during a time period (~5.6-5.0 mya) that is not very well known as there are few fossil rich sites of this time period.

 

This season's dig dates are over next week and they'll be tarping and sand-bagging the site for the rainy season. Digs will be starting up again usually sometime in October. Anybody visiting Florida during the dig season is encouraged to participate. It's less than 2 hours north of the much visited tourist sites in Orlando (the House of Mouse and the like). Consider spending part of your next Florida vacation on something more fulfilling (and cheaper) than theme parks. ;)

 

 

Cheers.

 

-Ken

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Hey Ken-  Looks like a great trip.  Thanks for taking us along.  Say Howdy to Tammy for me.   

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Will do so.

 

Fond memories of our time collecting out in Wyoming with you. Looking forward to our next trip out to the west.

 

 

Cheers.

 

-Ken

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