Monday, June 24, 2013

Bloodsuckers

Boyne shale at the PVPP.
We went back to Pembina Valley Provincial Park on Monday to look for shale outcrops, and while we met with some success, we mostly found a whole bunch of mosquitoes and woodticks instead. However, we did locate some neat Boyne shale outcrops, including some with iron content, as well as a weird-looking pyrite formation (found by Aaron) and a mosasaur vertebra (discovered by Eric). The backbone is particularly interesting because it's only the second local mosasaur ever found in the Boyne, which represents a time period where sharks like Cretoxyrhina are currently thought to have been more dominant in our part of the Western Interior Seaway. It had been washed down a creek bed and was weathered to the point of resembling a Pembina fossil in its coloring (we've got lots of those, but was determined to be from the Boyne after Joe (our paleontologist) tested it for calcium content by exposing it to hydrochloric acid. Unfortunately, any other bones from that particular mosasaur have likely been washed to random spots downstream (if they were ever fossilized in the first place).
Augen texture at the PVPP.

Our first two-day tour of the season occurred on Tuesday and Wednesday! Here's a shout-out to Ally Chernoff, who uncovered a number of mosasaur ribs, teleost (fish) teeth, and some more obscure fossils that we have yet to identify. From all the Field Techs, we really enjoyed digging for fossils with you in the field and we hope you had a great time. If any of you other readers would like to hunt for fossils with us, now's the time to schedule a tour since the weather's starting to really heat up, so don't wait! There's some cool stuff just waiting for you to uncover it at the CFDC.
Our awesome fort.



Matt Remple
Field Tech

Wednesday, June 19, 2013

The Cretaceous Seafloor

Diorama
Creatures of the Western Interior Seaway.
Whenever we take tours out to the field, one thing they always find a ton of is shale. Kids and adults alike can get sick of it pretty quickly and we often think of shale as being in the way since we're usually only interested in finding the fossils in it. However, shale is actually pretty neat in and of itself, and is only considered to be "boring" because it's so common. Many people don't realize that shale, although it's dry and dusty now, is former seabed from the Western Interior Seaway, which is where the animals that we currently find as fossils used to swim (sometimes even we field techs forget that!). Think about it: above the sea floor swam sharks, squid, and marine reptiles like mosasaurs and plesiosaurs, while closer to shore were numerous birds like Hesperornis and Icthyornis. Near the underlying seabed were all kinds of corals and shellfish, while tiny invertebrates burrowed through the murky bottom. The sea floor and the area above it were teeming with life; now, all we have are the rock remnants that they left behind, but there's still a multitude of things we can learn from them.
Shale layers; we mostly excavate
 in Boyne through Millwood.

There are several different shale layers that we find fossils in around Morden, each representing a period of time. These layers are usually quite different from each other, although certain layers are sometimes very similar (like the Millwood and the Upper Gammon that I've written about before). Changing composition of shale means that the conditions in the Seaway were changing as well. For example, a shale formation with high levels of bentonite indicate a lot of volcanic activity (bentonite is a common mineral formed from compressed volcanic ash). As well, fossils can have major differences in appearance depending on which layer they were formed in; fossils from the Pembina shale tend to be reddish-grey with fairly poor preservation, while Boyne fossils are black and shine gold in the sun. The Gammon Ferruginous can be extremely hard to dig through, but its fossils are likewise very well preserved.


Attempting to sift through Millwood.
Whenever we go to the field, we never refer to the rock we dig in as simply 'shale'; rather, we use names like 'Pembina' or 'Millwood' to describe the kind of shale we're excavating in, since the differences between layers are so pronounced. Odanah shale excels at staying dry when it rains, for example (making it popular for use on country roads), while Millwood and Upper Gammon are the only local shales that turn into sludge when they become wet. Last week, we tried sifting for shark teeth in some wet Millwood, but the stuff just clumps together and refuses to separate, so we didn't have much success. We might try again next week, but until then, we'll have to find fossils somewhere else.

Matt Remple
Field Tech




Tuesday, June 11, 2013

Kidsfest and the Millwood

Suzy's skull at Kidsfest.
Yesterday was the last day of Kidsfest in Winnipeg, our first major festival of the year. We spent five days there (I was at the booth on Thursday), and had a great time! Lots of kids had a blast with the fossil dig box, and we were right next to an awesome bug-catching exhibit from Oak Hammock Marsh. Factor in the presence of the excellent food at the Forks and it was time well spent for us at the CFDC.
The dig box. 



Now that Kidsfest is finished, we'll turn our attention back to field work, where a lot of cleanup remains to be done. For example, part of one of our sites is comprised of a ditch that grows into a small gorge. Due to all the rain we've experienced this spring, there's been a ton of water rushing down the ditch, causing it to become much wider and deeper than it was before. We used to have a ladder to facilitate transportation between the ditch and the upper part of the site, but the torrent swept it a ways downstream. I've since recovered it, but the ladder is no longer tall enough, nor is a sufficiently stable spot available, for it to continue to function in any helpful capacity. Now we're required to go around and cross further upstream to access the ditch, but it's still worth taking a trip down there every now and then. Once the stream dries up completely, we'll be able to explore the whole thing and maybe find some fossils that have been washed down to the bottom!
Which object doesn't belong?

On Wednesday, we also explored the Millwood shale for the first time since the rain started. Like the Upper Gammon, Millwood turns into a nasty, sludgy mess when it's wet, so it's been mostly inaccessible to us for the last several weeks. Dry Millwood, though, presents an interesting opportunity for fossil finding; Millwood shale doesn't have much sand in it relative to other local shales, making it clumpy and hard to dig in. Because of this, it's more efficient to search for fossils on the surface than to actively uncover them; we call this method 'prospecting'. Also, Millwood fossils are a dull black color, making them pretty distinctive compared to both the Millwood shale and fossils from the Pembina shale, which form the majority of our collection and sport a stone-grey coloration.

Millwood shale, next to a cattle pond (gross!)
During inclement weather (like what we've been having), the rate of surface erosion (and therefore fossil exposure) increases, making it likely that new fossils will be waiting for discovery at our Millwood sites. We spent a brief period of time prospecting at one site, where Joe, our curator and resident paleontologist, found several belemnites and what is likely a fragment of a mosasaur tooth (all I got were cow bones). Mosasaurs, which superficially resemble large crocodiles with flippers, are what our museum is most known for (Bruce and Suzy are both mosasaurs), while belemnites are tiny little cephalopods (like squid) that are fairly common.

Such have been our latest adventures! The weather's looking pretty nice for the next several days, so we should be spending most of our time in the field and have lots of new stuff to blog about at the end of the week.

Matt Remple
Field Tech