New Discoveries!



Xiphactinus Jaw

 

Monday, Anita and Joey had some very exciting finds: a Hesperornis femur (upper leg bone) and a Xiphactinus jaw.  Hesperornis regalis was a flightless marine bird from the Western Interior Seaway that was about 3 to 5 feet tall. They were somewhat like modern day penguins in that while they could not fly, and modern day loons in that they dove for fish. Unlike modern penguins, however, this Cretaceous bird had teeth!  Xiphactinus audax was a large carnivorous fish

Hesperornis Femur

 about 15 to 18 feet long. It is also called the bulldog fish, occasionally,  because of its resemblance to the canine. They were such great finds that on Tuesday, we decided to field jacket them.



Teaching us to field
jacket

After a dig tour on Tuesday, Lisa and I headed down to our research site where Joey, Anita and one of our volunteers, Tanya, were preparing to field jacket the fish jaw. They dug a small moat around the fossil, surrounding it with a buffer of shale. To protect the fossil we gathered mud from a nearby pond (dried up at this point), and packed it over the fossil as a protective layer. The next step was very amusing as we had to relive our kindergarten days and start playing with plaster! I was

Digging a trench under
the fossil

 the lucky one who got to mix the plaster: which was slightly stressful as you had to mix it to the right consistency and then hurriedly run strips of burlap through it before it hardened too much. Tanya and Lisa would then wrap the plaster-covered strips around the fossil, mud and shale so that there were no air pockets or sharp edges. It was a quick process as the plaster started to dry almost immediately. Next, after the plaster dried, we dug under the fossil so that it was on a type of pedestal. When there was enough room, four of us flipped the fossil and its matrix over so we could plaster the bottom. It was a delicate process as we didn’t want the fossil and shale to all fall out. Our first field jacket was a success as it made it back to the lab in one piece!  

 

Our finished product!



Our other research site has been turning up many interesting fossils. So far, it is mostly some fish and mosasaur vertebrae. I found a fossil that was half covered by a wall of overburden (extra shale that we always have to remove) and I was excited as to how far it might go under that extra layer. It turns out, it didn’t go very far at all, but there was another rib fragment right beside it. So, it was still exciting! My current dig spot has been consistently turning up smaller fragments and little fish fossils. We mapped our fossils: an interesting experience! Basically we had to set up a grid that was in line with our compass. We then had our artist, Lisa; draw every fossil that she could see within the grid on a grid map. This helps palaeontologists when they remove the fossils from the ground so they can remember where exactly the fossil was. 

The grid for mapping



Some palaeontologists like to study the area where the fossils were found: the taphonomy (studying the process of death to discovery) and maybe even how ocean currents and predation occurred. It’s very interesting!