Question on if the Northern Tyrannosaurid Nanuqusaurus survived into the Late Maastrichtian stage of the Cretaceous

[Joseph Fossil]

I was very pleasantly surprised (actually more thrilled to be honest) when I heard about the discovery of the northern tyrannosaurid dinosaur Nanuqusaurus hoglundi from the Cretaceous Prince Creek Formation dating 70.6-69.1 Million Years ago in what is now the U.S. State of Alaska.

 

Image Credit and Source: https://www.researchgate.net/publication/260757717_A_Diminutive_New_Tyrannosaur_from_the_Top_of_the_World

 

 

At first thought to be only 5-6 meters (16-20 feet) in length based on the currently catalogued specimens, it's now believed based on currently undescribed remains to be 8-9 meters (26-30 feet) in length fully grown (compared to the 12.3-12.4 meters (40.4-40.7 feet) in length it's cousin Tyrannosaurus rex could reach fully grown).

 

 

Image Credit: Artist Nathan Rogers

Image Source: https://www.artstation.com/artwork/Z5w900

 

 

Fiorillo, A. R., & Tykoski, R. S., 2014. A diminutive new tyrannosaur from the top of the world. PloS one, 9(3), e91287. https://doi.org/10.1371/journal.pone.0091287 

 

Druckenmiller, P. S., Erickson, G. M., Brinkman, D., Brown, C. M., & Eberle, J. J. (2021). Nesting at extreme polar latitudes by non-avian dinosaurs. Current biology : CB, 31(16), 3469–3478.e5. https://doi.org/10.1016/j.cub.2021.05.041

https://www.cell.com/current-biology/fulltext/S0960-9822(21)00739-9?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982221007399%3Fshowall%3Dtrue

 

 

The Tyrannosaurid Nanuqusaurus is also unique as the northern most tyrannosaur known from Western North America (at the time the continent of Laramidia). Adapted to the colder climates of the region, it shared its habitat with a vast diversity of plants, small mammals, and other non-avian dinosaurs including hadrosaurs such as Edmontosaurus, the pachycephalosaur Alaskacephale, the Ceratopsian Pachyrhinosaurus, and a large currently unnamed genus of troodontidae.

 

But it's confirmed geologic range is only during the early Maastrichtian (70.6-69.1 Million Years ago) of the Cretaceous period. 

 

Images Credits and Sources: https://www.researchgate.net/publication/260757717_A_Diminutive_New_Tyrannosaur_from_the_Top_of_the_World

 

 

Fiorillo, A. R., and Gangloff, R. A., 2001. Theropod teeth from the Prince Creek Formation (Cretaceous) of northern Alaska, with speculations on Arctic dinosaur paleoecology. Journal of Vertebrate Paleontology. 20(4):675-682

 

 

Image Credit: Artist Nathan Rogers

Image Source: https://www.artstation.com/artwork/Z5w900

 

 

 

The question I have is why this is? Did anything major happen to the habitat of the Prince Creek Formation between the Early-Late Maastrichtian? Did Nanuqusaurus live up to 66 Million Years ago to the latest Maastrichtian of the Cretaceous period?

 

 

[patelinho7]

Assuming Nanuqusaurus did not reach the latest Maastrichtian, I can only offer a guess: climate change? The world was getting hotter with more CO2 leading up to the end of the dinosaurs, maybe it limited food choices up in the tundra.

Edited March 6 by patelinho7

[jpc]

I did not know that the Prince Ck Fm goes into the Maastrichtian and even across the boundary, according to Fiorillo's diagram here.  Fossil sites are not common in the PCF, and my guess is that no sites have been found in the Maastrichtian.  If fossils are rare in the Maastrichtian, then theropod fossils tend to be even rarer.  Keep in mind as well that outcrops of the PCF are very limited, esp when you compare to other ate Cretaceous dinosaur deposits.  

 

How many dinosaur fossils are known from the Maastrichtian of the PCF?  That is the baseline question to answer.

[Joseph Fossil]

1 hour ago, jpc said:

I did not know that the Prince Ck Fm goes into the Maastrichtian and even across the boundary, according to Fiorillo's diagram here.  Fossil sites are not common in the PCF, and my guess is that no sites have been found in the Maastrichtian.  If fossils are rare in the Maastrichtian, then theropod fossils tend to be even rarer.  Keep in mind as well that outcrops of the PCF are very limited, esp when you compare to other ate Cretaceous dinosaur deposits.  

 

How many dinosaur fossils are known from the Maastrichtian of the PCF?  That is the baseline question to answer.

@jpc Good point. Thanks for the information on the Prince Creek Formation.

[Joseph Fossil]

@jpc I do think that Nanuqusaurus survived into the late Maastrichtian stage of the Cretaceous 68-66 Million Years ago, but we just haven't discovered yet outcrops containing Nanuqusaurus fossils from that part of the Cretaceous period.

[jpc]

44 minutes ago, Joseph Fossil said:

@jpc I do think that Nanuqusaurus survived into the late Maastrichtian stage of the Cretaceous 68-66 Million Years ago, but we just haven't discovered yet outcrops containing Nanuqusaurus fossils from that part of the Cretaceous period.

could be , but until we find the fossils, no need to spread rumors.   : )