Platecarpus planifrons

[Anthony]

Some of you may have noticed a conversation in the competitors section about a mosasaur found near the 17' Xiphactinus. This critter, the front half of a Platecarpus, identified as P. planifrons has been "show prepped" and is in pretty good condition considering the softness of the bone and he root rot and matting that encased the bone surfaceon much of it.

The frontal:


Jaws and quadrate:


More jaw and other quadrate:


Postorbital and jugal:

[Anthony]

Just a little update on the "IAN" project.

I've been asked to mount the specimen in a 3d full body mount, using parts of our other, very similarly sized P. planifrons from the lower chalk to fill in the missing pieces. Preparation is now complete and I am tasked with reassembling the skull. I hope you like the results, I should be done in about 1 week's worth of work. All pieces were photographed individually with scale before I started gluing parts back together, and the data will be put into a repository for future use.

This is what I started out with:




I started with mounting the frontals, postorbitals and parietal together. This gave me a good idea of where the Squamosals and prosquamosals would need to go.


The premaxilla was slightly crushed, and required some finessing to get to line up with the maxillas and the rest of the assembly. Jugals fit in just like they were supposed to. I never get that lucky.


View of the skull and my nearly identically sized 3d reference to the right



End of the day on Friday. The top of the skull is coming along, with a lower jaw to the upper right. Next week I have detailing around the prefrontals and nares to do, as well as fitting together the exploded braincase, lower jaws and palate units. Can't wait!

[Mike]

And you get paid to do this??   

Best of both worlds! Digging them up and putting them back together.

Nice work.

Mike

[Anthony]

Well, I couldn't even begin without OOK and the Mosasaur Meeting.

BTW Mike you're welcome to copies of the data as well for your records. As usual, just let me know if something interests you.

Bitten premax from a bad angle.

[Anthony]

Update on progress:

Quadrates are temporarily tacked on with hot glue for positioning. Lower jaws are together and I'm just getting up the nerve to start reassembling the braincase.



Lower jaw internal side:

[JJ]

Anthony, you have to get a kick out of going to work almost everyday.  Those photos are very informative.  Really, they're great!  Thank you for sharing them with us.  I really can't say how much I appreciate this site and OOK.  Thanks, guys.

[Mike]

Anthony,
I'll take the working on the brain case to re-assembling the lower jaws any day... looks like you did a great job there.

For the group, here's the skull of Platecarpus ictericus (upper chalk - MU 17) in a similar lay out for comparison.... somewhat less disarticulated ... which was good and bad... I never did get the left quadrate out of the orbit of the left eye.... 



More pics here.... (mostly scanned from 35 mm photos... many years ago)

FIELD - http://www.oceansofkansas.com/page11.html

PREPPED - http://www.oceansofkansas.com/page11a.html

FHSM VP-17017 was collected about 5 miles west of Russell Springs in Logan County, Spring, 1996.

Regards,

Mike

[Anthony]

Yeah, sometimes these things aren't totally removable. IAN has the tip of the right dentary's last tooth lodged deep into its left quadrate. I wonder if P. ictericus's braincase is different enough from P. planifrons to worry about, or if anyone has even investigated it.

[Anthony]

Braincase comparisons

IAN:


EMMA (Platecarpus ictericus):

[xiphactinus]

Seeing the tiny braincase of such a tremendous animal is amazing. Definately no advanced trig. going on there! Beautiful work, as always, Anthony!

[Mike]

There are characters within the brain case that are diagnostic to different groups of mosasaurs, especially the tiny openings for the blood supply and cranial nerves. That area of the skull is getting a lot more attention in recent papers (and in one that we will be publishing shortly in the Proceedings of the Second Mosasaur Meeting).... 

RE: Brain size.... A 7 m (22 ft) mosasaur had a brain about the size (and shape) of your index finger...

While that certainly is not a lot of computing power compared to us large brained, bipedal mammals  LOL .... it was more than enough to enable them to be apex predators for millions of years....

It's probably a subject for another thread, but you have to wonder if their nervous systems were somehow different.

For those of you interested in becoming mosasaur brain surgeons.... here's an endocast of a Platecarpus brain adapted from Russell (1967):

http://www.oceansofkansas.com/mosasaurs3/Braincase/TextFig-16_Brain.jpg

Scale is approximate..

Regards,
Mike

[Anthony]

Sophie was 41 feet long and had a brain cavity about the size of a small to medium deli pickle.

Then again you don't need much brainpower to eat eat eat.

Emailed Takuya, and he thinks that in general, there is very little diference in braincase morphology between the two chalk species of Platecarpus, so I'll just rough it out along the lines of my articulated example.

[Mike]

See the new thread on the brain and posterior skull of mosasaurs

Mike

[Anthony]

Ok, just got my metalwork master back from remounting the Apatosaurus in Laramie, so it looks like we'll be proceeding with mounting on Monday!

[Mike]

All,
Ken Barnes asked me to post these pictures of the basioccipital-basisplenoid of Platecarpus planifrons for him...

"I did not see a good basiocipital-basisphenoid for P. planifrons in Anthonys photos, I have a good one. Note that the tunnel for the basilar artery has a thin septum of bone seperating the two tunnels."
Ken Barnes 

Overall view of dis-articulated skull - BO-BS is inside circle


Dorsal view:


Ventral view:


Regards,

Mike