Question about a possible new species of Utahraptor from Early Cretaceous age deposits in the Mill Canyon and Arches National Park, Utah

[Joseph Fossil]

As I've continued my research and cataloguing of the prehistoric diversity of Giant Dromaeosaurs and other Eumaniraptora from the Cretaceous period, I found something rather fascinating regarding Cedar Mountain Formation Dromaeosaurids I would like you guys thoughts on. It's potentially either a new species of Utahraptor or an entirely new Utahraptor sized Dromaeosaurid from the Ruby Ranch Member of the Cedar Mountain Formation (121.4-100.5 Million Years ago) in what is now Utah.

 

 

Image: A Reconstruction Image of an adult Utahraptor's height compared to the average height of an adult Human by Paleo Artist FredtheDinosaurman, April 2019, this version of the created and posted 2023. 

Image Credit 1: https://www.instagram.com/extinctanimalsfacts/p/C0nsCj1vvqn/

Image Credit 2: https://www.deviantart.com/fredthedinosaurman/art/Oxford-Utahraptor-795349027

 

(I'm still adding to the list and here is the link if you would like to check it out):

Here are the following Sources:

Lockley, M. G., White, D., Kirkland, J., & Santucci, V. (2004). Dinosaur Tracks from the Cedar Mountain Formation (Lower Cretaceous), Arches National Park, Utah. Ichnos, 11(3–4), 285–293. https://doi.org/10.1080/10420940490428742
https://www.tandfonline.com/doi/pdf/10.1080/10420940490428742
 

Tweet, J., Lucas, S., G., Sullivan, R., M., & Santucci, V. (2018). AN INVENTORY OF NON-AVIAN DINOSAURS FROM NATIONAL PARK SERVICE AREAS. Fossil Record 6. New Mexico Museum of Natural History and Science Bulletin 79. 703-730. 

http://npshistory.com/publications/paleontology/nmmnhs-79-703.pdf

Lockley, M., G., Gierlinski, G., Dubicka, Z., Breithaupt, B., H., & Matthews N., A., (2014). A new dinosaur tracksite in the Cedar Mountain Formation (Cretaceous) of eastern Utah: New Mexico Museum of Natural History and Science, Bulletin 62, this volume. 
https://juraparkbaltow.pl/wp-content/uploads/2018/07/Lockley-Gierlinski-Dubicka-Breithaupt-and-Matthews-2014.pdf

 

Lockley, M., & Gierlinski, G., & Houck, K., & Lim, J. D., & Kim, K. S., & Kim, D. Y., & Kim, T. K., & Kang, S. H., & Foster, R., & Li, R., & Chesser, C., & Gay, R., & Dubicka, Z., & Cart, K., & Wright, C.. (2014). New excavations at the Mill Canyon Dinosaur Track site (Cedar Mountain Formation, Lower Cretaceous) of Eastern Utah. New Mexico Museum of Natural History and Science Bulletin. 62. 287-300.

https://juraparkbaltow.pl/wp-content/uploads/2018/07/Lockley-Gierlinski-Dubicka-Breithaupt-and-Matthews-2014.pdf
 
Xing, L., et al. (2024) Deinonychosaur trackways in southeastern China record a possible giant troodontid. iScience. 109598. https://doi.org/10.1016/j.isci.2024.109598
https://www.cell.com/iscience/fulltext/S2589-0042(24)00820-4

 

 

[Joseph Fossil]

This potential new species of the genus Utahraptor is known from several fossilized tracks dating to the late Aptian-Albian stages of the Early Cretaceous (4 tracks from Mill Canyon as part of 1 trackway, 2 from Arches National Park as part of 2 trackways). 

 

Image Source: https://www.researchgate.net/publication/285086715_New_excavations_at_the_Mill_Canyon_Dinosaur_Track_site_Cedar_Mountain_Formation_Lower_Cretaceous_of_Eastern_Utah

 

 

The tracks are also fairly large at both sites, with the largest of the Mill Canyon tracks being 21.0 cm. In length (NA for Width) and the largest of the Arches National Park tracks being 28-35 cm. In Length (NA for Width). In contrast, the recently discovered large Troodontid (called tentatively Fujianipus yingliangi) footprints from the Late Cretaceous Shaxian Formation in what is now Southeastern China were about 36.4 cm. In Length (16.8 cm. for Width) (Specimen LXIU-T3-L5) and came from an animal with a hip height of 1.8 meters (5.9 feet) and up to 5 meters (16 feet) in length.

 

 

Microsoft excel chart (Table S2) for information for the following chart image.

 

mmc2.xlsx

 

Source: https://www.cell.com/iscience/fulltext/S2589-0042(24)00820-4

 

 

 

Image: Chart demonstrating accurately the Morphology, age, and geographic distribution of Mesozoic deinonychosaur tracks (numbers correspond to Table S2) (Note: Number 34 corresponds with the largest footprints of the Unnamed Shaxian Formation Giant Troodontid (Specimen LXIU-T3-L5) and Numbers 21-22 correspond with the Unnamed Large Dromaeosaurid from Mill Canyon and Arches National Park in what is now Utah), 2024.

Image Source: https://www.cell.com/iscience/fulltext/S2589-0042(24)00820-4

 

 

[Joseph Fossil]

I thought originally the Mill Canyon and Arches National Park fossilized tracks belonged to a large individual of the known species Utahraptor ostrommaysi as the tracks are from the Cedar Mountain Formation. However, specimens of Utahraptor ostrommaysi are currently only known from the Yellow Cat Member section of the Cedar Mountain Formation (with a possible occurrence in the Poison Strip Member section of the Cedar Mountain Formation). These sections date to 139-134.6 Million Years ago during the Berriasian-Valanginian stages of the Early Cretaceous period.

https://paleobiodb.org/classic/basicTaxonInfo?taxon_no=66450

 

In contrast, the fossilized track specimens from Mills Canyon and Arches National Park are from the Ruby Ranch Member section of the Cedar Mountain Formation. This section dates to 121.4-100.5 Million Years ago during the Aptian-Albian stages of the Early Cretaceous period. That's at least 13.2 million years after the geologically youngest Utahraptor ostrommaysi specimens currently known.

 

With that said, I'm wondering if these tracks point to an unnamed second species of Utahraptor or entirely new Utahraptor sized Dromaeosaurid younger than Utahraptor ostrommaysi in what is now Utah?