Saurornitholestes Skull Study Results

[Troodon]

Another important dinosaur paper that is paywalled.  Went the rental route again.  

The paper takes the first good look at the Skull of the Dromaeosaurid, Saurornitholestes langstoni from the Dinosaur Park Formation.  It provided great insight into Dromaeosaurid's and specifically the dentition which we as collectors are most interested in.   Similar species are found in Montana's Judith River and Two Medicine Formation.   The biggest surprise were the premaxillary teeth, they are distinctive, and teeth previously identified in the Dinosaur Park Formation as Zapsalis abradens can now be identified as the second premaxillary tooth of S. langstoni.  The morphology and wear patterns suggest that these may have been specialized for preening feathers.   Zapsalis is one of those tooth taxons and brings into question if its indeed valid or just synonymous with Saurornitholestes.  The paper makes the following statement  "The similarity  between the premaxillary teeth of Saurornitholestes and Zapsalis show that the latter is a dromaeosaurid and suggests that the two genera are  synonymous. However the differences suggest they are distinct at least at the species level.  Pending the discovery of additional Associated skeletal material from the Judith River formation of Montana it is recommended that the two genera be kept separate." 

 

The holotype tooth of Zapsalis (right) from the JRF is slightly different than the Saurornitholestes tooth.   See Fig.  

Might just be tooth to tooth variations.

 

 

 

https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.24241#.XXZqJ1PoYmg.twitter

 

Cranial Anatomy of New Specimens of Saurornitholestes langstoni (Dinosauria, Theropoda, Dromaeosauridae) from the Dinosaur Park Formation (Campanian) of Alberta

Philip J. Currie, David C. Evans

First published: 09 September 2019

https://doi.org/10.1002/ar.24241

 

 

 

@hxmendoza

@-Andy-

[fossilsonwheels]

Fantastic information to share with us Frank. Very cool.  I do not have any Zapsalis teeth but I may start looking for one from the JRF. Teeth for preening feathers would be a really awesome adaptation to talk about with students!

[Troodon]

14 hours ago, fossilsonwheels said:

Fantastic information to share with us Frank. Very cool.  I do not have any Zapsalis teeth but I may start looking for one from the JRF. Teeth for preening feathers would be a really awesome adaptation to talk about with students!

 This morphology of tooth is also found in other formations like Hell Creek and Lance Fm.  Probably belonging to Acheroraptor with this new information.  Before Acheroraptor was described all its teeth were assigned to cf Saurornitholestes.  Not common and often misidentified.  Indeed an interesting adaptation.

[-Andy-]

Very interesting info. Thanks for sharing Frank. Hopefully new skull material of Acheroraptor show up soon to give us more answers

[Troodon]

This is a good example of why tooth taxons can be very problematic.  

 

In the Hell Creek/Lance we have a few

Aublysodon now viewed as invalid and is an indeterminate tyrannosaurid 

Paronychodon most likely a pterosaur, under study

R. isosceles most likely a pterosaur, under study

Pectinodon looks valid but no skeletal material found

 

 

 

[Troodon]

Actual skull used in the study

Comments by D. Evans

"The articulated skull revealed a couple of surprises: 1) facial proportions w tall, robust snout-contrast w Velociraptor; 2) giant, specialized premaxillary teeth, formerly assigned to own taxon Zapsalis, might have been adapted for preening it’s feathers"

 

[LordTrilobite]

That's a very nice skull. Good to see it's finally studied. Too bad the paper is paywalled.

I wonder if the rest of the specimen is being studied as well. I've seen images of it online some time ago. It looked like an almost complete skeleton.

[Troodon]

14 minutes ago, LordTrilobite said:

I wonder if the rest of the specimen is being studied as well. I've seen images of it online some time ago. It looked like an almost complete skeleton.

Quote from the paper

"The purpose of this submission is to focus on the cranial anatomy of Saurornitholestes. However, the specimen includes a nicely preserved skeleton that has a furcula, an ossified sternum, an opisthopubic pelvis, sternal ribs, and uncinate processes. These, and other relevant postcranial characters, will be described in a separate paper but have been included in the coding used for the phylogenetic analysis."

[Troodon]

Here is D. Evans (co author) response my question about this morphology on Acheroraptor in the HC 

 

"The enlarged premaxillary teeth are found in a number of different derived dromeosaurs (Velociraptor, Bambiraptor), and were probably present in many others. We would predict that Acheroraptor would have the same teeth as well. I doubt the teeth themselves are terribly diagnostic to the species level, but there might be some phylogenetically significant variation there. The problem is that there are so few specimens that preserved the teeth in situ in a skull that can be identified to genus."

[fossilsonwheels]

On 9/10/2019 at 10:46 AM, Troodon said:

Actual skull used in the study

Comments by D. Evans

"The articulated skull revealed a couple of surprises: 1) facial proportions w tall, robust snout-contrast w Velociraptor; 2) giant, specialized premaxillary teeth, formerly assigned to own taxon Zapsalis, might have been adapted for preening it’s feathers"

 

That is awesome !! Beautiful skull that is providing important knowledge. Thanks again for sharing this with us Frank

[LordTrilobite]

Just found this out, but the paper isn't paywalled anymore.

[Troodon]

1 hour ago, LordTrilobite said:

Just found this out, but the paper isn't paywalled anymore.

Thanks for posting just saw that myself, here are some more from 

 

https://anatomypubs.onlinelibrary.wiley.com/toc/19328494/2020/303/4