Dinosaur Park Formation and Belly River Group in Montana?

[dinosaur man]

I recently learned that the Dinosaur Park Formation and in general the Belly River Group is in Montana!  In parts of Kennedy Coulee, Milk River Badlands, is this true?

[Troodon]

And where does it say the BRG is in Montana? 

You have to remember not to long ago that these late Campanian deposits were called the Judith River Group.  Today the distinction is made at the border Judith River Fm on one side and BRG on the other.  

 

 

[dinosaur man]

4 hours ago, Troodon said:

And where does it say the BRG is in Montana? 

You have to remember not to long ago that these late Campanian deposits were called the Judith River Group.  Today the distinction is made at the border Judith River Fm on one side and BRG on the other.  

 

 

It doesn’t just fill out say it but in the text above it says “Ray teeth collected from microsites throughout Kennedy Coulee, from the Herronton Sandstone to Unit 1 of the Oldman Formation, possess smooth-sided crowns, and are thus referable to Pseudomyledaphus sp. (S1 Text, S1 Fig) [20]. In Alberta, Pseudomyledaphus sp. are only found in the Foremost and lowermost Oldman Formations [20–22], supporting the assignment of MOR 2919’s locality to the lowermost Oldman Formation.” and it is possible they can overlap a bit as the Two Medicine Formation goes into Alberta, so if the Two Medicine could do that it is possible for the Belly River Group too?

[Kane]

Stratigraphic nomenclature in general is a complicated issue, and there isn't always consensus. Moreover, paleocommunities can differ significantly over distances, just as you may notice differences from your hometown's prominent flora and fauna compared to 100 km up the road. A species common in two formations does not necessarily make those two formations identical, or suggest the presence of that formation elsewhere. Remember that your claims are restricted to what the literature says, and that any inference or speculation beyond that would require evidence.

 

In future, do make an effort to supply the full attribution for any quoted material, as that is a courtesy to the author(s) and a good habit to get into if you have designs to go into research.  For (fictitious) example:

 

Smith, J. 2020. A revised biostratigraphy of the Oldman Formation. Journal of Vertebrate Paleontological Research 43(2):122-199.

[Troodon]

I can read the text no need to restate it.  I ask again where does it say those units are found in montana. 

 

Those units are separated just by geography Canada, usa.  Just like Hell Creek/Lance Fm thise by state line.  They are basically equivalent deposits 

 

 

[dinosaur man]

1 hour ago, Troodon said:

I can read the text no need to restate it.  I ask again where does it say those units are found in montana. 

 

Those units are separated just by geography Canada, usa.  Just like Hell Creek/Lance Fm thise by state line.  They are basically equivalent deposits 

 

 

Oh so if there equivalent deposits and are only separated by the Canada-US border, wouldn’t that make the Upper Judith River Formation, basically the Dinosaur Park Formation in Montana though, won’t this mean that most likely the dinosaurs of the Judith River formation are basically and most likely the same animals found in the Belly River Group, or are most/some of them different compared to the Dinosaur Park Formation, due to geography?  And is this the same with the US Two Medicine Formation and the Canadian Two Medicine Formation?

6 hours ago, Troodon said:

 

 

 

[dinosaur man]

So in other words on what I’m trying to say are they the same Formation with just a different name for in Canada and the US or are different Formations with there own unique Fauna?

[Arion]

If I’m reading the original paper you cited correctly, the objective was to establish an age for the Kennedy Coulee site, using a combination of radiometric dating and the presence of Pseudomyledaphus as an index fossil. You mentioned it not ‘full out saying it,’ (BRG in Montana), but a key part of good scientific writing is ‘full out saying it.’ If you know something to be true, you say ‘this is true;’ if you suspect something to be true, you say ‘I suspect this to be true.’

 

I personally find Late Cretaceous dinosaur faunas in western North America to be really interesting because we have such a high-resolution picture of how they changed over a relatively short period of time. So to compare the Judith River Formation with the Dinosaur Park Formation, for example, we’d need a very precise time correlation and might expect evidence of the same species being present in both formations. Brachylophosaurus canadensis is present in both, as far as I know, but there isn’t significant species overlap as far as dinosaurs are concerned.

 

There does seem to be a basis for a North-South geographic partitioning of dinosaur species in LC western North America. Although the same families of dinosaurs are present throughout the whole region, you find different collections of faunas the farther north you go (so, for example, Utah has its own fauna, Alberta has a slightly different one, Alaska has a slightly different one, etc.). With this in mind, I’d be cautious about lumping Alberta and Montana together too quickly.

 

As @Troodon mentioned, it wasn’t that long ago that the Judith River formation was applied to strata in Montana, Alberta, and Saskatchewan. And as @Kane mentioned, this can be a complex issue that isn’t just a case of political boundaries.

 

EDIT: Mercuriceratops gemini is also from both DPF and JRF.