Meet Our Giant Turtle

Last summer the Burke's fossil preparator, Bruce Crowley and a team of volunteers excavated a giant turtle - but finding it was only the beginning.

The fossil was first spotted on this rocky outcrop. Bruce and volunteers dug around the area where the bone was visible to make sure they got every piece of the fossil.

Enough of the bone was showing to tell that they belong to a prehistoric soft-shelled turtle (the family Trionychidae). The geology of the area tells us that it's about 49 million years old.

Bruce wheels in the giant turtle.

The fossil and the rock surrounding it were covered - first with aluminum foil (or paper towel or toilet paper), then with plaster. The aluminum foil prevents the plaster for sticking to any exposed bone, and makes it easier to remove once it's back at the museum.





Inside this plaster jacket are the fossil remains of a 49-million-year-old turtle. But for the moment, it's covered in rock and it's heavy.

Now that the jacket is in the fossil prep lab at the Burke, the team can begin to remove the rock that surrounds the bones.

Once the rock is removed, the turtle could prove to be the biggest fossil turtle in the Burke's collection.

Bruce uses a cast cutter to open the plaster field jacket. The black tube in the upper left of the photo is a vacuum to suck up plaster dust and dirt. Bruce wears a mask to protect his lungs from plaster powder.

The fossil prep setup. Bruce uses a vacuum cleaner to clean up dust in the work area.

After a couple weeks of work, fossil bone is exposed. It may not look like much, but what you see here represents a lot of work.

The sandbags are used as wrist rests while Bruce works on the bone with air-powered "micro jacks" - tiny, miniature, hand-held jack hammers.

In this close-up of the work area, taken about 2 weeks after the field jacket was first opened, you can see part of the fossil bone exposed. The orange stuff in the upper right is glue to keep the rock from splitting while Bruce is working and breaking the fossils inside.

You can see the giant fossil turtle this Saturday at the Burke's annual Dino Day. From 10 am (9 am if you're a Burke member!) to 4 pm, get an up-close look at the turtle and talk to Bruce and other Burke paleontology experts. 

Posted By: Winifred Kehl, Communications

The Dinosaur in the Lobby

Paraphysornis brasiliensis

Like many natural history museums, the Burke has a dinosaur in the lobby. Ours just happens to be a terror bird. (All birds are dinosaurs, but not all dinosaurs are birds!) In honor of this year's Dino Day, meet our terror bird.

The theme of Dino Day this year is "Predators and Prey"—and terror birds were top predators. These giant flightless South American birds had huge hooked beaks and sharp claws. Ranging in size from the 3-foot-tall Psilopterus lemoinei to the 10-foot-tall Brontomis burmeisteri, they probably killed their prey by stabbing it with their hooked beak. Their strong legs might have helped hold down struggling prey while the beak stabbed and ripped it.

Terror bird foot

As for who they ate, we can't be sure. Larger terror birds probably could have eaten small- to medium-sized mammals.

There are no birds alive today close enough to terror birds to tell us exactly how they lived and hunted. Modern large, flightless birds—ostriches, emus, rheas, and cassowaries—are not hunters (although they can be dangerous). Terror birds' closest living relatives, the seriema, may be close to what the smallest terror birds looked and acted like.

Terror bird head

The Burke's terror bird is a cast (replica) of Paraphysornis brasiliensis. It lived in Brasil 23 million years ago.



Dino Day 2012 is coming up on Saturday, March 3rd!

Posted by: Winifred Kehl, Communications

How to Make a Fossil Cast: A 10-step Guide

If you came to Dino Day this past weekend, especially if you came with a kid, you probably saw the Burke’s brand new fossil dig pit.  In the dig pit was a cast of an ichthyosaur fossil from the museum’s paleontology collection.

And you may have wondered: What steps go into creating a cast of a fossil?

Creating a fossil cast is a multi-step process (I’ve reduced it here to 10 steps). Over a few days in January, I followed around fossil preparator Bruce Crowley and his team of volunteers as they worked on creating the mold and pouring the cast of the ichthyosaur.

Step 1: Get the original fossil out of storage and uncrate it.

Step 2: Identify the area around the fossil that is going to be cast; build a barrier and apply a layer of silicone to the fossil -- this will easily come off later (the silicone in this picture is purple).

Step 3: After covering the rest of the exposed fossil with plastic (gotta protect it!), begin to spread on a layer of plaster (in this case, a material known as Hyrdocal). While spreading the plaster, add criss-crossing layers of fiberglass sheeting—this will reinforce the Hyrdrocal and make a nice plaster jacket for the fossil. Be sure to work fast and don’t forget to wear gloves and a mask.

Step 4: Come back the next day and the plaster jacket is complete!

Step 5: Very carefully, remove the plaster jacket from the silicone layer.

Step 6: Remove the silicone layer from the fossil. See, I told you it would come off easily!

Step 7: Back in the lab, place the silicone layer (aka the mold) on top of the plaster jacket (for reinforcement) and build a wall around the silicone. If this step is overlooked, the material used to pour the cast will spill over and onto the floor!

Step 8: Pour the cast into the mold! (Again, using a brand of plaster known as Hydrocal) When done, the cast will look like this:

Step 9: Remove the cast from the mold.

Step 10: Paint the cast…it helps accentuate the different parts of the fossil!

There you have it! It’s a perfect cast of a real ichthyosaur fossil! And the kids at Dino Day loved uncovering it in the dig pit.

Posted by: Julia Swan

Dino Day Limerick Competition!

Let me admit something about myself: I love limericks. I love writing them, I love reading them. And guess what else I love: dinosaurs! And since everyone at the Burke is in full-on excited mode for Dino Day this Saturday, this afternoon I decided to pose a challenge to my fellow Burke Bloggers. “Write me your best Dino Day limerick,” I said.

Then we decided to ramp up the competition and see who could take the best picture with our informal Burke mascot, Tyno Rex.  So readers, tell us: who wrote the best limerick? Who took the best picture? Give us your answers in the poll below.* And please, if you love limericks as much as I do, write one for me and post it in the comments.

Contestant #1: Julia Swan

This Saturday, don’t sit around being a bore,

Come to the Burke to see a real dinosaur!

Whether you fancy your dinos big or small

Our Dino Day event will have it all

From T Rex teeth to a full Stegosaur

Contestant #2: Karin Moughamer (guest blogger!)

This Saturday visit the Burke
Where paleontologists will showcase their work
Take a fossil journey through Antarctica, Patagonia and Wyoming
And learn about the dinosaurs that went roaming
Your kids (and you) are sure to go berserk!

 














Contestant # 3: Andrea Barber

Large teeth, sharp claws and small limbs

Dinosaurs were more than just a whim

So I’ll find my way

To the Burke’s Dino Day

And see dinos that could run, fly and swim!

 



Contestant #4: Samantha Porter 
(with a slight breach of the rules, she submitted her best dino haikus)

Dinosaur fossils
It’s paleo’s biggest day
Fun is not extinct

Sometimes there’s free cake
Fossils, wombats, Dinosaurs
I so love my job

Haikus are my friend
Julia’s talent: limericks
Sam: jealous of that

Who wrote the best limerick?

• Julia
• Karin
• Andrea
• Sam

View Results
Create a Blog Poll

Who took the best picture with Tyno Rex?

• Julia
• Karin
• Andrea
• Sam

View Results
Create a Blog Poll

And of course, don't forget to come to Dino Day this Saturday! 

* Update: as of 3/8, Sam is the clear winner of the photo contest and while she has the most votes for best limerick, she actually wrote haikus, so I'm awarding best limerick to the runner up, Andrea

Posted by: Julia Swan