Theropod footprints

[flemgunner]

Hey y'all just started a job on a ranch and they have a very nice theropod trackway. Has at least 10 tracks maybe more. Some are covered by cast off from a mountain. 

Im fairly sure they are Jurassic but still need to get better gel maps of the area. 

Anyway my question is what is the best stuff to make a cast of a couple of them. I know plaster of Paris but as with anything is there some new super bad stuff out there?

thanks much

[FossilDudeCO]

Here in Colorado at our dinosaur track sites, we still use plaster on the track itself.

Seems to work very well. Then we can make a mold from that cast and use any other medium we may want.

 

[flemgunner]

Do y'all use burlap or anything to strengthen it?

[flemgunner]

Here's a pick of one

[FossilDudeCO]

1 hour ago, flemgunner said:

Do y'all use burlap or anything to strengthen it?

 

Not when we made the original cast, just poured in the plaster!

Just make sure you sweep out as much of that sand as you can so it is clean

[JohnJ]

It depends on the shape of the track.  If there are any 'undercuts' (places that the casting material cannot lift straight up), then you will need a flexible casting material.  Also, to prevent any damage to the tracks, I think some kind of release agent would be advisable. 

[flemgunner]

What's a good release agent for plaster?

[JohnJ]

Release agents for plaster

[FossilDAWG]

Interesting project.  I've not heard of any Jurassic exposures in Texas, but there is a lot (!) of Cretaceous and some formations are well known to produce trackways.  A rough indication of the locality would allow us to check geological maps and suggest a possible age and formation for your find.

 

Don

[Fossildude19]

Apparently, there are some Jurassic sediments exposed in Texas, However, ... they appear to be marine in nature.  

 

This PDF says " Texas has hardly any exposed Jurassic rocks and therefore no dinosaurs from that period." 

 

So, it's more likely that the Tracks are Cretaceous in age.  

Large theropod tracks from Texas are typically attributed to Acrocanthosaurus. 

 

[flemgunner]

I agree with yall all the Geo maps Ive seen have over whelming Cretaceous deposits but supposedly these have been seen by a geologist and he suggested the date. I am, at best, an amateur so Im going by that.

Ive only been out here a couple weeks so havent really had time to map out anything.

Im near Uvalde Tx BTW

Glenn

[Fossildude19]

Geologic map of Texas.

 

Close up: 

 

     

 

Key

 

[flemgunner]

Cool thanx. Im going out to em today after work. Ill try to get more pix and a shot or to of the surrounding rocks

 

[JohnJ]

Don and Tim are right; there are no Jurassic exposures in Uvalde County.  These are Cretaceous age tracks. 
Geo Map

[erose]

1 hour ago, flemgunner said:

I agree with yall all the Geo maps Ive seen have over whelming Cretaceous deposits but supposedly these have been seen by a geologist and he suggested the date. I am, at best, an amateur so Im going by that.

Ive only been out here a couple weeks so havent really had time to map out anything.

Im near Uvalde Tx BTW

Glenn

Not the first time a geologist got it wrong. I have also heard some completely inaccurate stuff from archaeologists who are often confused with geologists or paleontologists.  But if that was Uvalde County there is not much chance it is Jurassic. But the Lower Cretaceous Glen Rose Formation, which is dominant in the northern end of the county, is well known for dino prints.

[doushantuo]

useful or not?

[flemgunner]

As far as the info here? Heck yeah! Way appreciated and very usefull

[doushantuo]

don't get me started

[JohnJ]

45 minutes ago, JohnJ said:

Don and Tim are right; there are no Jurassic exposures in Uvalde County.  These are Cretaceous age tracks. 
Geo Map

 

The surface geology and subsurface geologic units are quite different in this part of Texas.   

[jpc]

Sounds like you have some cool stuff there.  I would strongly suggest NOT using plaster to make casts.  Plaster has NO bending properties... it is too stiff.  Plaster is fine for modern tracks in dirt as you end up getting rid of the original track.  As mentioned above if there are any undercuts, even little ones, you may never remove it, or you will break either the plaster or the imprint.  Most professionals use latex with cheesecloth as a strengthener.  It is not a quick and easy process as you need to paint several layers of latex on there and let each one set up before adding another one.  

 

[flemgunner]

Thats good info. Can you recommend a place to get those?

[flemgunner]

Went down there a few minutes ago. They are covered by water and some by debris but you can still see 4 real well and another in a different direction I hadnt seen before that has a nice claw mark.

 

[flemgunner]

Wont let me upload the track way picture so here is the link.

 

 

[jpc]

https://www.aeromarineproducts.com/product/mold-making-latex-rubber/?size=1-quart&gclid=CPrOmbz8q9ICFQQHaQod1x0H-Q

 

https://www.amazon.com/Builder-Liquid-Latex-Rubber-473ml/dp/B001E1XBLO

 

http://www.dickblick.com/products/amaco-rubber-latex/?clickTracking=true&wmcp=pla&wmcid=items&wmckw=34120-1006&gclid=CPKZ0-b8q9ICFYW4wAodLXkOSQ

 

My guess is that yu will need at least a pint for this.  They sell a separator as well (see the amazon listing above).  While you are making the mold in situ, add a bit of extra latex in the undercuts so that eventually there will be no undercuts.  Thenk you can make a mothermold out of plaster.  This is needed because the latex will not hold its shape, and the mother mold will help it do that.  remove the plaster, remove the latex and put the latex back into its position in the plaster.  you are now ready to make a copy of the footprints in your creek by pouring some plaster into the mold.  Mix some sand into the plaster for a more sandstoney look.  

 

you can also use silicone for the mold, but that is much more expensive than latex.  

 

Good luck.  Feel free to PM me any questions you might have.   

[FossilDAWG]

Those new photos really make the tracks clear, especially the view up the creek bed.  Way cool!

 

Don