Help! Live/Current Atco Reptile Excavation

[Heteromorph]

6 hours ago, The Amateur Paleontologist said:

Looking forward to seeing how this turns out!

-Christian

I’m in the process of sending the pics to Polcyn.

Can only hope the rest is still in the ground! 

[The Amateur Paleontologist]

2 minutes ago, Heteromorph said:

I’m in the process of sending the pics to Polcyn.

Nice! Are you also gonna get in touch with Mike Everhart about this?

 

3 minutes ago, Heteromorph said:

Can only hope the rest is still in the ground! 

Would be really neat if there's cranial material! Fingers crossed  

-Christian

[Heteromorph]

18 minutes ago, The Amateur Paleontologist said:

Nice! Are you also gonna get in touch with Mike Everhart about this?

 

Would be really neat if there's cranial material! Fingers crossed  

-Christian

I guess I could, but isn’t Everhart more shark stuff? I am wading into somewhat unusual territory for myself, since I am usually hunting invertebrates, and I still don’t quite know what I am doing yet. 

 

Also, don’t you find Mosasaurs where you are? And if you do, how old are they? Just curious.

[The Amateur Paleontologist]

6 minutes ago, Heteromorph said:

I guess I could, but isn’t Everhart more shark stuff? I am wading into somewhat unusual territory for myself, since I am usually hunting invertebrates, and I still don’t quite know what I am doing yet. 

 

Also, don’t you find Mosasaurs where you are? And if you do, how old are they? Just curious.

It's true, Everhart is more into sharks, but he has written quite a few good papers on Kansan mosasaurs - so I figured he might be able to help

 

In the part of France where I live, there are virtually no mosasaur remains...

However, at Møns Klint, the Danish chalk site where I go each year, mosasaur remains can be found - they're from the Lower Maastrichtian, about 70 million years old. They are, though, exceedingly rare - the only mosasaur remains from that site are 4 or 5 teeth (and the first one was found in 2007). I have yet to find one

 

-Christian

[Xiphactinus]

13 minutes ago, Heteromorph said:

I guess I could, but isn’t Everhart more shark stuff? I am wading into somewhat unusual territory for myself, since I am usually hunting invertebrates, and I still don’t quite know what I am doing yet. 

 

Also, don’t you find Mosasaurs where you are? And if you do, how old are they? Just curious.

M Everhart is very much into mosasaurs. He could help ID things for sure. 

[Heteromorph]

From Polcyn today:

 

“Thanks for contacting me. Great find! I would need to take a closer look at the specimen prior to making a more detailed ID, but it falls within Russellosaurina, the group that includes tylosaurines and plioplatecarpines. I am heading to Africa in a few day for field work and will be back in Dallas at the third week of July. I would encourage you to keep a close eye on the site and if it looks like there is a concentration of bone or any skull material that becomes exposed, I would encourage you to leave it in place and protected, so that it could be excavated properly so as not to damage anything and lose important information. I will have access to email periodically, so keep me in the loop. I would like to look at your find when I return. 

All the best,

Mike”

[JohnJ]

Awesome!

[The Amateur Paleontologist]

3 hours ago, Heteromorph said:

From Polcyn today:

 

“Thanks for contacting me. Great find! I would need to take a closer look at the specimen prior to making a more detailed ID, but it falls within Russellosaurina, the group that includes tylosaurines and plioplatecarpines. I am heading to Africa in a few day for field work and will be back in Dallas at the third week of July. I would encourage you to keep a close eye on the site and if it looks like there is a concentration of bone or any skull material that becomes exposed, I would encourage you to leave it in place and protected, so that it could be excavated properly so as not to damage anything and lose important information. I will have access to email periodically, so keep me in the loop. I would like to look at your find when I return. 

All the best,

Mike”

Great! He seems quite interested in the specimen

[PFOOLEY]

On 6/16/2019 at 2:30 AM, Heteromorph said:

...Thus concludes my first successful (partial) extraction of an associated vertebrate specimen. 3:28 a.m....

Dedication.

 

Good work.

[Heteromorph]

It has now been 2 weeks since the excavation, and in that time I have been able to get some good pictures of my finds from the site. I have also done a bit more research about the zone of the Atco which it exposes.

 

The site exposes a marly zone of the lower Atco, about 10-15 feet above the basal Atco, which lies directly above the underlying Eagle Ford group and approximately marks the Turonian-Coniacian boundary in North Texas (I think?). The basal Atco is locally famous for being a lag deposit which holds tons of vertebrate material, especially many kinds shark and bony fish teeth, and can rarely have completely articulated fish and various marine reptile material. Invertebrates like ammonites, gastropods, and inoceramids are also very common. The horizon is easily noticed due the the high density of phosphate pebbles in the deposit that gives it a chocolate chip ice cream look.

 

FIG 1: This and next two pictures show various views of the site, including freshly exposed marl in FIG 2 and scattered phosphate pebbles weathering out in FIG 3.

[Heteromorph]

FIG 2.

[Heteromorph]

FIG 3.

[Heteromorph]

FIG 4: A chunk of basal Atco for comparison.

 

This zone, just a few meters above the basal Atco, is obviously different from it in that the latter is shalely, gray, and harder than the marl, which is soft and pinkish when freshly exposed to tan when weathered. They are, however, similar in that they both contain abundant vertebrate and invertebrate material and both have many phosphate pebbles, though the pebbles in the marl don’t seem to get as big as those in the basal Atco. The deposit is also a bit thicker than the basal Atco, being at least 2 thirds of a meter thick as opposed the the basal Atco, which in the same area is about a third of a meter.

 

Because the basal Atco is just a few meters below this horizon, the marl often gets overlooked. I didn’t even know much about it until I happened upon this site and started seeing the phosphate pebbles everywhere, which immediately rang in my mind as a cue to get down on my kneepads and crawl the exposure, with good results. When I started researching the zone I remembered a post by @vertman, in which he describes the same horizon and finds mosasaur material such as I have. The pictures he posted also show many phosphate pebbles.

 

The fauna of the site is dominated by vertebrate material, with the most common finds being shark teeth without their roots and fish teeth, though shark teeth with roots can be had. At the site, the only shark species that I have found so far are Cretodus crassidens and Squalicorax falcatus, but vertman also reported Ptychodus mortoni (a species that does not occur in the basal Atco) and Scapanorhynchus texanus from this zone, which makes sense since I found associated P. mortoni teeth a few feet higher at a nearby site, but in proper limestone. There are other odds and ends, including fish scales, teeth, and vertebrae, and invertebrates like phosphatized ammonites, gastropods, and bivalves. I also found a somewhat large yet incomplete regular echinoid spine, a first for me from the Austin group. Along with phosphate, small pyrite nodules are also common.

[Heteromorph]

FIG 5: A phosphate pebble in proper limestone.

[Heteromorph]

FIGS 6-8. This and next 2 pictures show various in-situ finds.

[Heteromorph]

FIG 7.

[Heteromorph]

FIG 8.

[Heteromorph]

FIGS 9-14: This and next 5 pictures show some of the smaller fauna of the site.

[Heteromorph]

FIG 10.

 

FIG 11.

 

FIG 12.

 

FIG 13.

 

FIG 14.

 

Now to my articulated mosasaur. Nine vertebrae were found on the surface, some of them still articulated. As I dug further I continued to expose more verts until I decided to dig up a block containing those I could see still in-situ, which of course was quite a project. During excavation I made sure to document my finds as best as I could.

[Heteromorph]

FIGS 15-16: The 9 mosasaur vertebrae as found on the surface. The blue line shows the in-situ location of the other articulated verts still buried in the marl.

[Heteromorph]

FIG 16.

 

FIG 17: Notebook in which I made a primitive bone bed map, numbering each exposed vertebrae. The numbers correlate to those shown in the following pictures.

[Heteromorph]

FIGS 18-29: The mosasaur vertebrae. Three articulated sets are shown. Above picture is a dorsal view of this caudal set.

 

FIG 19: Right lateral view.

 

FIG 20: Ventral view.

 

FIGS 21-23: Both articulating surfaces, this and next two pictures.

 

FIG 22.

 

FIG 23.

[Heteromorph]

FIG 24: Dorsal view.

 

FIG 25: Ventral view.

 

FIGS 26-27: Both articulating surfaces, this and next picture.

 

FIG 27.

 

FIG 28: Dorsal view.

 

FIG 29: Ventral view.

 

So for now I am leaving the site alone until Polcyn is able to see the specimens in late July. I don’t know if this mosasaur specimen would be interesting enough for them to ask me to donate it, but if it is I would gladly do so.

[Tidgy's Dad]

Nice report and a wonderful find. 

I love all the associated fauna pics as well. 

[Heteromorph]

31 minutes ago, Tidgy's Dad said:

Nice report and a wonderful find. 

I love all the associated fauna pics as well. 

Thanks!