Saturday, August 29, 2015

Fieldwork Flail -The Ups and Downs of Being Out and About

Hello, Dear Readers!

Well, the thesis is off to the committee (eep!), so now I get to digitally dust off the blog and leave the academic hermitage that is writing thesis chapters! I've been figuratively chained to the office for most of the summer. While this was a self-imposed office banishment, having to stay indoors and write during the summer when every fiber of my being was screaming to be outdoors doing fieldwork wore on me. Needless to say, once the writing was done, I jumped at the opportunity to visit one of my favorite neoichnology sites before all the shorebirds abandoned us to the cold weather (thanks, birds). The site is a couple of hours drive from the museum and great for (long) day trip fieldwork.

What follows is a mixed bag of success and frustration: in short, it's the typical field story. 

I arranged with our summer field tech, Linda, to pick her up at 6am. I went to bed early, as I'd be up before the sun to put the finishing touches on my neoichnology field gear. Thanks to some horrid reaction to something I ate, I did not get to sleep until 2am. As I finally drifted off to sleep I thought "Oh, this trip is starting out well..."

The alarm blares off at 5am. I will be honest with you: I am not a morning person, even when I've had a decent night's sleep. "Good" is not paired with "morning" in my vocabulary. Our museum staff (morning people, the whole lot of them) take great delight in being all chipper around me when I first enter the building. The walking dead have more life in them than I do on waking. Several cups of tea infused me with what passes as life, I picked up Linda, we loaded the last of the gear into the field truck, and left town for a pleasantly uneventful drive to the site.

Oh, sorry. I slipped into telling fiction. Back to reality.

We were driving down the highway, which is pleasantly empty at this time of the morning. This means that I'm not ticking off the drivers who want to do 100-120km/hr by driving the speed limit (90km/hr). Given the driving habits of the region and the fact that we are smack dab in the middle of the BC wilderness, there are a lot of black tire marks on the highway. I didn't think anything of that new black mark on the road...until I was close enough to see that it had thickness. I slowed and swerved around whatever it was...

BANG!

My foot left the gas immediately. We slowed to a crawl. This let me know that a) my tire(s) were still attached to the truck, and b) the axles (if damaged) would last long enough to get us to a safe shoulder. We crept along the road until we found a turn-off to a gravel road, engaged the hazards, and stepped out to survey the damage.

The flattest of all tires.

Important Field Tip #1: Know how to change the tires on your field vehicle. Don't just assume that you know how to change a tire - actually practice on your field vehicle before you set off on your adventures. Everyone on your field crew needs to practice being the lead on changing a tire. Even though we were right on the highway, we had no cell service and the satellite phone was being twitchy, so there would be no calling BCAAA.

Fortunately for me and Linda, while we had not been the leads on changing a tire, we knew enough from several assists how to do it. The most troublesome part of the process was lowering the bloody spare from under the vehicle because we couldn't find the thrice-damned attachment for the jack that fits into the decent mechanism. Which leads me to...

Important Field Tip #2: Keep all of your jack attachments in one area, even if they are small. It took longer than it should have to locate the proper attachment, which was helpfully located in the glove compartment. Once located, we were off to the races, so to speak. During the process we also encountered...

Important Field Tip #3: People are jerks. Don't trust that they will bother to stop, slow down, or even move their vehicle as they roar past you at 110km/hr on a relatively narrow highway. Out of the seven vehicles that drove past, not one even slowed down. This was all well and good - we didn't need help (and we didn't want the hassle of trying to tell someone that the damsels in distress actually could change a tire all by our little selves), but the gravel and dust being whipped at us from speeding trucks got old.

The tire change went smoothly. Once the tire was off...
we could see the extent of the damage. Whatever the tire had hit, it went right through. There would be no patching this tire. That tire wasn't just damaged: it was cancelled.
Linda shows us the extent of the damage.
That was Adventure #1. We decided that we deserved to stop at Tim Horton's before continuing on to the site. We also made a note of our location, because on the way back we planned to find the wretched thing in the road that thrashed the tire.

We made it to the parking area of the field site without any incident. Accessing the neoichnology site requires crossing a river. Usually the river is gentle and shallow enough at this location to cross without too much difficulty. However, recent rains had given the river a bit of vigor and depth. Each of us had a cumbersome load to pack across the river (plaster, mixing buckets, cameras, personal gear), and the local river bed flora add a nice element of slime to the bouldery river bed. Crossing would prove to be tricky.

We found a spot that looked promising, and started across. A combination of bulky gear, slimy boulders, and a slight misstep sent me flailing into the river.

SPLASH!

All I remember going in was thinking "S**t, the camera!" and holding that aloft with my right hand while my left hand let go of the bucket (which Linda retrieved before it floated off on its own adventure) and broke my fall. This area was deep enough that I didn't break my fall before going almost completely under the water - I think the top of my head was still dry - but the palm of my left hand took the full force of my fall as it hit boulders and gravel. Needless to say, there was a little bit of damage.
It's only a flesh wound...I hope.
I carry a first aid kit with me, but there was very little I could do at this point that couldn't wait until I reached civilization. Sure, I could have dug around in my hand to remove bits of embedded gravel, but nice cushiony blisters formed around the impact sites, so I knew where the offending material was located. What worried me more was the sharp ache deep in my first metacarpal - did I break or crack it? I could still move it, albeit with some discomfort, so I figured we had come too far to give up on the chance of shorebird traces.

We finally crossed the river, and I changed into more-or-less dry clothes. We had arrived!

This area is dominated by Canada Goose tracks, and the fine-grained sediment captured their trampling nicely.
Canada Goose trample surface.
With the Canada Goose tracks were smaller anseriform (duck) footprints: they have a different overall shape than Canada Goose tracks, so we knew they weren't young geese.

Duck, duck, (not) goose. Do you see the inward curving outer toes?
Did you see the webbing? Webbing is a useful feature when it preserves, but webbing is inconsistently preserved in bird tracks. If the sediment consistency is just right (firm yet damp, like a firm wet beach sand), webbing may not impress. A more reliable feature is the curvature of the lateral toes: members of the duck group (Anseriformes) with palmate webbing (a completely webbed three-toed foot) have digits II and IV (the outer two toes) that curve towards the middle digit (digit III). Sandpipers with semipalmate webbing (webbing that attaches only partly down the length of the toes) do not have inward curving side toes.

Part of neoichnology is hanging out in an area long enough to see the local wildlife. Ideally, you want to see the animal in question make the footprints. If that isn't an option, you need to know who is frequenting the area. If the tracks you are looking at are fresh, there's a better chance that the trackmakers you see are the owners of those footprints. These tracks were relatively fresh, so I knew that there was a good chance the trackmaker was either nearby or would revisit the site. All we had to do was wait.

While we were waiting, we checked out the track surface for more examples of the same type of footprint preserved in different ways. Here is a great example of how there is not one preservational scenario that will preserve all features all the time.
The webbing on these Canada Goose prints is very poorly preserved, but the hallux (digit I) on the left footprint is gorgeous! Digit I is another one of those birdy features that is inconsistently preserved, yet so many rely on the presence of the hallux impression as THE feature for saying with 100% certainty "Yes! We have a bird print!" I have a paper in press that discusses how the fossil and neoichnology data shows it's rarely that simple. Stay tuned!

We also found great samples of skin impressions for Canada Goose footprints. This print doesn't look like much at first glance - no webbing, no hallux, no "heel" pad (which isn't really a heel, but a fleshy pad where the toes and the end of the metatarsals connect)...
...but on closer inspection, it has great skin impressions!
A close-up look at the footprint shows that it preserves the creases, ridges, and pebbly texture on the bottom (plantar surface) of this Canada Goose's foot.

We also found evidence of our mammalian friends on the track surface: guess who?
If you guessed wolf, you would be correct!
Grey Wolf trackway overprinting the multiple trackways of Canada Goose. Bonus question: was this wolf walking or moving faster than a walk?
While we waited for the arrival of our small ducks (we could hear some quacking in the distance) we made a few plaster of Paris replicas of the different preservational variations of the Canada Goose and the as-of-yet unidentified small duck tracks.
Small duck trackway being cast.

The track surface with plaster replicas (white patches) drying.
Making replicas of modern tracks is a really simple process, and it's something that anyone of any age can do. We use a fiberglass-reinforced plaster of Paris (Hydrocal FGR-95). I also add additional fiberglass matting to the backs of the replicas, as many of my track casts are long and thin. Field neoichnology casting is a cumbersome process: you have to haul out plaster, mixing containers, fiberglass mat (or chop, but that's a pain in the butt to work with) and garbage bags. You also have to haul the awkwardly-shaped plaster casts out of the field. However, I think it's worth it for bird tracks. We're getting mixed results with digital photogrammetry on small bird footprints, and one of the reasons is that they are often wet, shiny, and partially underwater. All of this extra reflection confuses the computer program, which "prefers" even, consistent lighting for all of the images used in making the 3D digital replica. Also, plaster replicas are cheap to make, and I'm an ichnologist on a very strict budget.

This brings me to Important Field Tip #4: Pack it in, pack it out. We mix all of the plaster in a container placed inside a garbage bag, and any plaster drips and slops are collected after they harden. We don't want to leave a trace while we collect traces.

While we were waiting for the replicas to dry, we saw that our small ducks had arrived!
This is a horrid picture, but viewing these ducks through my binoculars let me know that they are Green-winged Teals in their non-breeding plumage. They are a small brown dappled duck, but one was kind enough to rearrange its wing feathers long enough to show me the green patch.

This was a good day for ducks, but where were my shorebirds? We scanned every centimeter of this shoreline, crossed over this waste-deep body of water to a second projection of land and scoured that for shorebird prints, and came up with almost nothing. We saw really faint impressions of Spotted Sandpiper footprints, but they were made in such wet mud that they had all but collapsed in on themselves, leaving nothing but faint lines where the toes impressions should be. We were about to call ourselves skunked in the shorebird category when we came across this:
FINALLY!
It turns out there were a pair of Spotted Sandpipers at this locality, but they were being extremely sneaky with us. We turned every corner just to see them flying away: none were comfortable with us in their territory, and they were more or less avoiding walking in areas that would keep an impression of a footprint for more than a few minutes. This was a huge change from last year, when two Spotted Sandpipers took a short nap while I was taking photos of them. On our way back to the field truck at the end of the day, we found out the little buggers had doubled back on us and were foraging in the areas we had already prospected. This brings me to my final Important Field Tip: you can't control your wild study taxa. Some days they cooperate, while on other days they flip you the feathery Bird.


This was a typical field excursion, full of wins (great duck and goose tracks) and fails (the Thrashing of the Tire and my new gravel piercings). Regardless of the frustrating parts, it was great to be back in the field!

Until next time,
SAS

P.S. - My thumb turned out not to be broken (yay!) but it was swollen and sore for a few days. Here is a picture the day after I landed on it. Luckily the blisters were just impact blisters - there were no embedded gravel chunks to remove.

Monday, June 22, 2015

Do LEGOs Dream of Electric Dinosaurs?

This Monday was shaping up to be a Monday: administrative duties, extra workload to get ready for the Geopark inaugural events this weekend, and on top of it, general thesis writing freak-out. What I was not expecting this morning was this:



Time for straight-up honesty:

1. I have not yet seen "Jurassic World" (GASP!) From what I have seen of released clips and trailers, I agree with Dr. Victoria Arbour and Dr. Angelica Tories on their assessments of the tired female lead themes in their reviews here and here, respectively. I also agree with their and Dr. Darren Naish's review of the movie-monster style versions of the theropods that could have been so so so much more fun and creepy (our heroes encountering a Velociraptor gently cleaning the blood and tissue of its latest human kill off of its feathers to the gently sounds of the forest, anyone?) I'll see Jurassic World one day soon, but it's likely not going to be until after I defend my doctoral thesis.

2. I do not play video games and did not grow up playing video games. Our idea of a video game was when the Pong machine was hooked up to the TV. After that, we inherited an old Commodore 64 and played "Tanks" and text-based games on the sepia-toned screen. I am not the person to ask technical questions of when it comes to "How can I access X, Y, and Z features?" I don't own a PS-Anything. Dammit Jim, I'm an avian anatomist and ichnologist, not a video game person! (I just finished watching Star Trek TOS.)

All that being said, it was pretty cool to discover that I was LEGOed! LEGO-Lisa even has the right colored field shirt!
Oh yes, I get to ride the Parasaurolophus. I'm not sure about flying the helicopter, but in a choice between dinosaur and chopper, the dinosaur wins. Image from Gameslingers at Dawn.
Kris Abel, author of Gameslingers at Dawn, was able to customize some characters for the Jurassic World LEGO game. Kris went for Canadian paleontologists. These characters are available for anyone to play (from what I understand). I'm in good company as I get chased through the park by Indominus rex and her like. Running from (Towards? With? We all know it's either towards or with) the dinosaurs is Philip Currie (University of Alberta) and his theropod pack, as well as David Evans (Royal Ontario Museum) and his ceratopsian troop. Follow the above link for the unlock codes for the characters!

If you play the LEGO video games, you'll have to let me know how LEGO Lisa fares on her adventures with her buddy hadrosaur (we have an unofficial name for the airlifted specimen, but it's too geographically specific, and we are still keeping the site location under wraps for the time being until we can get the proper excavation funding.)

Riding off into the LEGO sunset,

LEGO Shaman.

Friday, June 5, 2015

Queen of the Flies

*Note: contains images of animal skulls in various stages of preparation. Ick Factor medium. Just be glad this post doesn't come in Surround Smell-o-vision.

Ever had a Friday where you come into your office and wonder "Where the heck did these bloody flies come from?"

No? Just me?

I'm really not surprised by that. I have a rather odd science-related side project at the museum: I maintain a dermestid colony.

What are dermestids? Dermestid beetles (and these guys are actual beetles, being part of the Order Coleoptera, or "sheathed wing" beetles with a hard outer wing covering) are scavenger beetles of the genus Dermestes: they are also known more colloquially as "flesh-eating beetles" or skin beetles.

These beetles aren't flesh-eating like the stylized movie scarab beetles in "The Mummy". These beetles are scavengers: you would have to be quite dead in order to attract the interest of a dermestid beetle. In fact, the Dermestidae are important in the realm of forensic entomology, as their presence on a body (for example) is an indicator of how long it has been exposed.

Dermestidae are considered by the non-natural history person as a commercial and household pest: they can be found infesting pantries, shipments of dried protein (pet food is commonly afflicted), and any place where humans (and their pets) cook, eat, drop a bit of food, shed, store food...the most common place to find dermestid beetles in your home (yes, you have them) is in pet foot areas, under ovens, along baseboards on floors, and in the tracts of windows - basically any place where food, hair, and other dead insects accumulate.

The most common dermestid beetle you will see in your home (at least, in Canada) is the larder beetle (Dermestes lardarius). Having these beetles in your home doesn't mean that your home is dirty (although if you seem overrun with them, you may want to call a pest management expert); these beetles are a natural part of Nature's clean-up crew.
Adult larder beetle. insectsofalberta.com

Larval larder beetle. Royal Alberta Museum.

Although Dermestes are considered a pest, it is uncommon for natural history museums to keep a colony of dermestids. These beetles are an important part of a museum's research team, as they very happily clean tissue and skin off of bones, leaving the bones to be cleaned, archived, and used in a variety of research and outreach projects. The most common beetle I have heard of employed (they literally work for jerky) at museums is Dermestes maculatus, the hide beetle. Museums and labs that I know of that use dermestids are the Royal Ontario Museum and their skin beetles, the American Museum of Natural History, and the Witmer Lab at Ohio University, to name just a few.
Adult hide beetle. http://entnemdept.ufl.edu/creatures/misc/beetles/hide_beetle.htm

I started a wild-caught dermestid colony as an experiment I fully expected to fail. I scoured my home for a few larder beetles, and persuaded friends to find larder beetles in their homes. I had a grouse specimen (road kill) that I had left to dry in the basement of the museum, and placed the grouse mummy in the box with the dermestids and a few layers of unbleached corrugated cardboard. Lo and behold, the larder beetles took to their work with great enthusiasm! I quickly expanded my one colony to three separate ones (Homeworld, Earth That Was, and Miranda), and was soon contacted by local wildlife authorities to clean some of their skulls that they had set aside as teaching specimens.

My beetles became something of local celebrities. Recently I was interviewed for CBC Radio Daybreak North about how dermestid beetles can help paleontologists with their research. The beetles have also made guest appearances for our summer education camps. It's no surprise that when you ask a room full of kids "Hey, does anyone want to see some flesh-eating beetles?" there will be several that say "EW! Yeah!"

While dermestids are thought to prefer dried tissue, they actually quite like wet tissues, but in the wild they are out competed by fly larvae. I experimented by putting in a whole thawed skull of a grey wolf, hide and all. I wanted to see how long it took my colony to clean a skull from start to finish.
Dermestid adults, busy at work.

I covered the skull with paper towel, as the beetles like to work under cover. Every few days we mist the paper towels with water, and the larvae and adults come out to drink.


It took almost a year (my colonies are small), but the beetles completely stripped the skull of all of the fur (in which they now burrow to pupate), and the hungry larvae ate all of the hide and tissue.

Dermestid beetle colonies are simultaneously simple and frustrating to manage. Since they love to eat, burrow, and pupate in dry organic material, they are a potential archives hazard. The room in which the colony is kept should be sealed so these little escape artists (which they are, under certain circumstances) cannot leave. Any specimens prepared using dermestids have to be quarantined in a freezer for a few weeks to kill any remaining adults, larvae, and eggs. They will climb if there is ANY texture at all on the inside walls of their colony container: I went through three types of plastic bins before I found one with smooth enough sides to foil these tenacious scavengers. If you use an old aquarium, they will climb up any of the silicone sealant used on the corners. The adults fly at temperatures above 20 degrees Celsius, so the colony container must have a lid. Since the colony container needs both a lid and air, the colony ventilation must be such that other members of Nature's clean-up crew, specifically flies, cannot enter. This is where we start today's adventure.

Recently I added a fresh skinned wolf head and a great grey owl head to Miranda Colony, which was already processing an adult black bear. I've been in and out of the office for the past three weeks, and every time I peeked in on the colonies, they were doing well. Smelly, but well. So, I figured I would let them alone for a week before I went in to disturb them. Today I noticed a big black fly in my office, buzzing around like a B52 Bomber. Rather annoyed at this, I swatted it and gave it no more thought...until a second fly buzzed its way in. Hmm. Flies plus dead tissue...uh oh. I poked my head out of the office, and the hallway light in front of the dermestid room had several flies on it. I went in and saw this in Miranda Colony:
J'accuse!


After almost three years of never having a fly infestation here I was, Queen of the Flies. This called for immediate action. Taxidermy forums suggested hand-picking maggots and eggs off of the skulls, but, my Dear Readers, I LOATHE maggots with a burning passion that will never die. I went for option #2: freeze the suspect skulls, muck out the colony, and seal it off until all the flies have emerged and died.

I needed supplies. I flew (haha) to the local dollar store and picked up these:
Yeah...this group of purchases doesn't look sketchy at all!
The nylons and duct tape were for constructing new, fly-proof container lids. The garbage bags were for the contaminated skulls. The jerky dog treats were for the newly cleaned colony: the dermestids will eat them, but the flies will have little use for them. The fly-swatter is self explanatory.

I hauled all of the colonies outside to inspect them. Homeworld and Earth That Was had no traces of either adult flies, pupae, or larvae in the container (that I could see). Here's a young black bear skull, full of nothing but dermestid larvae and adults.


Both Homeworld and Earth That Was received new nylon lids. Until I can find larger sections of nylon, these lids are taped down to hold them in place. They will be more of a hassle to use when I need to access the colonies, but for the time being they will keep out any remaining flies that may be buzzing around. Another benefit is that these nylon lids will keep any flies that I may have missed contained within the respective colonies. I don't need any more trouble makers flying around my bug room.


I moved on to Miranda colony. Sure enough, several adult flies were in there. I picked those out and examined the skulls. The (not so) fresh wolf skull contained damning evidence: fly pupae.
Adult and larval larder beetle at top of the image, fly pupae at the bottom.

After being picked off and thrown in the trash, every skull in Miranda Colony was deposited into a heavy duty garbage bag. They are now all suspect, and all need to be quarantined.

Great Grey Owl head.
Adult black bear. This skull is about 3/4 finished. It's likely the flies would have no interest in the remaining dried tissue, but it's headed (pun totally intended) for the freezers.

Once the skulls were removed and double-bagged, I removed all of the loose bedding and towel covers. I stripped the colony down to its bare essentials, leaving the cardboard in which the dermestids like to burrow, and the layers of detritus they have built up.


Since the remaining dermestid adults and larvae still need to eat, I added the dog treat jerky. The dried meat will be of little interest to the flies, but will keep the dermestids well fed.

Once I added the jerky (the dermestids found it right away), I sealed up the container with a nylon lid. I also added an X to the side, just to remind me that this is the colony under surveillance. It didn't take long for two more flies to emerge.


With the colonies under control, I added the bagged skulls to the freezer. In this case, I'm not too worried about freezer burn.

What's next? I'll be monitoring all three colonies closely. Any flies that emerge will not be able to escape and infest the neighboring colonies, and any flies emerging will be removed. If I find flies in Homeworld and/or Earth That Was, those skulls will join the others in the freezer for quarantine. Freezing will also kill any dermestid eggs and larvae on the infested skulls, but this is an acceptable loss to avoid turning my work area into a scene from Amityville Horror.

I find all of this rather embarrassing. My colonies have been functioning without such an infestation for around three years, even with fresh specimens. Fortunately it is a short-lived problem, and I caught it early.

Stay tuned for more Adventures of Dermestia, Mistress of the Flesh-Eating Beetles! Will she win her battle against her dark alter ego, Queen of the Flies?

UPDATE 07-June-2015:

Well, my friends, the Queen of the Flies has been elevated to the Empress of Flies. My fly containment system has worked - to a point. Unfortunately Earth That Was has fallen to the scourge of all that is fly, and new flies have appeared in that colony. There were so many flies trapped in Miranda that I put that colony outside (it's above freezing here at night now, so there is no danger to the dermestids).

What will I do now? Tomorrow I will do a full colony strip-down and rebuild of Miranda and Earth That Was. Time to start fresh, so to speak. This will entail:
1. Removing and freezing skulls in Earth That Was.
2. Salvaging as many of the adult and larval dermestids as possible from each colony in separate containers.
3. Binning all of the comfy detritus the dermestids have built up for themselves. No matter how carefully I sift, I risk missing fly eggs, larvae, and pupae.
4. Wash out the two containers. Let air dry.
5. Lay down new corrugated cardboard and new polystyrene foam (they LOVE to burrow into the foam for pupating).
6. Add salvaged beetles.

I'll post an update on the salvage work tomorrow or the next day.

Until then,
Empress of Flies.

UPDATE 11 - June - 2015:

I have, for all intents and purposes, rebooted Earth That Was and Miranda. To date Homeworld remains fly-free.

After we removed the young black bear skull, a Purple Finch, and the legs of a Great Horned Owl for quarantine in the freezers, my lab tech Linda and I hand-picked as many adult and larval dermestids as we could find. All of their bedding (and any beetles that refused to be found) had to be binned. We saw several fly pupae during the beetle picking.

Adult larder beetles, ready to be pioneers in their new home.

We placed our rescued beetles in clean 5 gal. buckets with pieces of corrugated cardboard, dry cat food, and turkey jerky treats (for dogs). The larvae will burrow into the cardboard to pupate.

Close-up of the larder beetles examining their new food.
We closed off the lids of the rescue colonies with several layers of cheesecloth, and thoroughly cleaned the old colony containers. Once the skulls are out of quarantine, I can transfer the beetles and the skulls back to the larger containers.

Rescue colonies for Earth That Was and Miranda.
So far the beetles in all three colonies are doing well. They have an appearance to make during the inaugural weekend (June 27-28) for the Tumbler Ridge Geopark.

Stay tuned!

UPDATE: 18 August 2015 - Response to Comment

Since I am having internet issues with the comments section, I will respond to the latest comment from Dermy/compostguy101 in the text of the blog. One of the great parts of having experiment colonies is having lab notes!

My response:
Thank you for your interesting comment. These colonies are experimental colonies of wild-caught Dermestes lardarius from the region. These colonies are set up to test the "preferences", if you will, of these beetles for osteological specimens in various stages of prep.

In my description of the observations I've made from 2010-2015, I'll be using terms that appear anthropomorphic, but it's how the curators/techs at the museums I consult with refer to their beetles, and it's done with the understanding that it's in jest. While it appears to be common knowledge that dermestids require fully dried specimens to process, my observations of the colonies for a few years have shown that dermestids do quite fine with "fresh" material - a dose of ethanol on the surface of the specimen retards rot/decay (and the beetles appear to love a little booze with their meal). I was advised that meaty skulls and specimens are great for growing colonies, and my observations have confirmed this advice.

A pre-colony freeze is standard operating procedure for adding any dead wildlife to the dermestids. The freezing process is a little more complex than just thaw and add - one should partially thaw specimens and then refreeze. I playfully call this "shock and thaw" - any eggs/larvae that were able to survive the initial freeze are shocked and killed during Freeze 2 as they are emerging from dormancy.

Specimens that the beetles have successfully prepped from whole (eviscerated for entire specimens) include:
Adult Grey Wolf (skull)
Adult Black Bear (skull)
Adult Cougar (skull)
Adult Wolverine (skull)
Red-tailed Hawk (2, whole)
Great Horned Owl (whole)
Great Grey Owl (whole)
Northern Goshawk (whole)
Several small sparrows, flickers, warblers, grouse.

In their natural setting, flies (and their resulting maggots) out-compete dermestids. When dermestids are the only scavenger in the ring, they readily consume fresh and dried material. Actually, I have to time the addition of new skulls properly, because if I add fresh material to the same colony as a half-prepped dry specimen, the beetles will focus their efforts on the fresh skull. This was an pleasant surprising observation, given the myriad of "thou shalt not add fresh material!" lines of instructions on setting up/maintaining colonies. For large skulls I prefer to hang them just long enough to stop dripping - this cuts down on the chance that molds will grow in the colonies.

Also, while it is also common knowledge that the tongue, eyes, and brains need to be removed prior to adding skulls to the colonies, these are, without fail, the first parts of the skull that the beetles tackle. This is the stage that freaks visitors out the most - most people are not comfortable with seeing larvae and adult beetles wriggling around an eye socket or a mouth. It must invoke memories of horror movies.

I have not had any adverse reactions to using dried pet kibble in the colonies. My observations have shown that cat food is preferred over dog food, and I use the ends of the bags that my cat gets tired of. Actually, I've added several new batches of dermestids from infested pet kibble bags. Most people end up returning those to the store, but when you deal in beetles, it's a bonus!

Seeing as how I am not prepping skulls commercially (there is no "fast enough" for this experiment), I am willing to be patient as my colonies grow, and to not overgrow for the size of our facility. I have no timeline to keep. These colonies are for our small (but growing!) osteology collection, and for introducing kids to part of Nature's garbage crew. Kids are the one exception to the beetles in eye sockets observation - they think its simultaneously gross and, to quote one kid, "freaky-cool!" One day I aspire to have a large-museum set up for the colonies - where, as I've heard for one large museum, you can stick a whole fresh chicken in the dermestid colony and have it processed in three days - but I am purposely keeping the colony at a size that is manageable for this facility.

This was an issue of lids not being secure enough, coupled with a lot of open doors due to our renovation. 

Saturday, April 25, 2015

We Need Help to Fund Summer Dinosaur Track Research!

Hello Dear Readers!

Regardless of the snow that is on the ground as I type, this is the time of year our planning kicks into high gear for this summer's field season. We have an exciting new dinosaur ichnology project (for new readers, ichnology is tracks, traces, and other "signs" left by dinosaurs other than their body parts), thanks to the sharp-eyed residents of the Peace Region who reported the site to us, and the guarantee that we can operate this year.

"Wait, Shaman - didn't you say you were office bound this summer in your last post?"

Indeed I am, friends. However, that doesn't mean I'm not hard at work ensuring the field season can happen for my Research Team. As a Museum Of Unusual Size (MOUS), we struggle every year to not only convince the Powers That Be that our institution (the Peace Region Palaeontology Research Centre) is a worthy project for conserving, archiving, researching, and interpreting British Columbia's fossil heritage, we have to justify WHY research should be funded. We have no access to research funding through provincial or federal means. We always approach the natural resource companies operating in the region for potential partnerships, and are usually given the same rebuff: "Our head office decides funding levels based on population size. You live in a small population center. You will get a small amount." Trying to convince them that this project is regional and provincial in scale does not make an impression.

This year we're trying something different. Two days ago I launched an Indiegogo campaign to crowd fund the research for our Williston Lake Tracksite (link to the "Research Dinosaur Tracks in Northeast BC, Canada!" campaign site here.)

There's good background information on the campaign page, but I'll also provide a summary here.

The new Williston Lake Tracksite is a large, flat exposure of the Gething Formation (Early Cretaceous, approximately 115 million years old). Dinosaurs in BC - and specifically dinosaur footprints - have a long, but little known history in the province. Tthe cultural history of many British Columbia residents of European descent (there may be First Nations historical recognition for the tracks - still hunting out info) has long assumed that "there are no dinosaurs in BC, they're found in Alberta" - I heard this so often growing up in BC that I wanted to scream. However, dinosaur prints were first found in northeast BC by geologist F. H. McLearn in 1922-23. Paleontologist Charles M. Sternberg led the first paleontology expedition to the Peace Region in 1930.

C. M. Sternberg named many new ichnotaxa (footprint types) from the Peace River Canyon Gething Formation sites in 1932 and on. This was the first extensively published description of Cretaceous tracks as a footprint community (ichnofauna). Several ichnotaxa were named:

Amblydactylus gethingi - here's a footprint and handprint pair from a different tracksite, not the original Sternberg locality.  Amblydactylus is thought to be made by a dinosaur related to Iguanodon.

Medium-sized herbivorous dinosaur print Gypsichnites pacensis (image not Sternberg's original site):

The small theropod footprint Irenichnites gracilis. This specimen is not from the original Sternberg localities:

Medium-sized theropod footprint Columbosauripus ungulatus (image not from Sternberg's sites):

Large-sized (and likely allosaurid) theropod prints Irenesauripus (from Sternberg 1932):

Last, but certainly not least, the ankylosaur footprints of Tetrapodosaurus borealis (image not from the Sternberg localities, but from our Flatbed Creek Trackway Tour site):

Later, Currie (1981) named what was, at the time, the oldest bird footprints known, and the second
bird footprints named from North America: Aquatilavipes swiboldae.
From Currie (1981).

There are two things I'm sure you have noticed by now:
1. The Peace River Canyon tracksites are important. Several type specimens come from there, and they are an important part of not only British Columbia's history, but the history of paleontology. The Province of British Columbia agreed, and in 1930 the Peace River Canyon site was designated as a Provincial Heritage Resource. Cool, right?
2. Most of the images are not from the original Peace River Canyon localities. Why? The Peace River Canyon localities, a Provincial Heritage Resource, are now flooded under the "Dinosaur Lake" reservoir of the Peace Canyon Dam. Despite a huge salvage effort by the Provincial Museum of Alberta (now the Royal Alberta Museum), led by paleontologist Dr. Philip Currie between 1976-1979 that recovered over 90 footprints, mapped 1000 prints, and in total documented 1700 prints, the sites and the in-place tracks were lost to future science, science outreach, and tourism opportunities.

This new site, the Williston Lake Tracksite, is the first large-scale track-bearing surface from the Gething Formation that has been seen since the flooding of the Peace River Canyon. We have this fantastic opportunity to continue Sternberg's and Currie's work.

First, we simply need to documenting the site. It won't really be simple: there's A LOT of site to be cleared (in yellow):

We need to map all of the footprints in place as they appear on the surface. We need to take latex and silicone molds of significant footprints and trackways. We also need to 3D-digitize the ENTIRE site.
We can take an entire tracksite back to the lab with us in 3D-digital replica format. Image from McCrea et al. (2014b).

Why do we need to do this?

We need to know a) what track types are there, b) what proportion each track type is in this slice of the paleo-ecosystem, and c) update or revise Sternberg's footprint identifications (as needed) with our advanced understanding of how footprints work - Sternberg did a great job in 1932, but our understanding of footprints has increased and changed a lot since then, and since the original Sternberg sites are inaccessible, we have this golden opportunity to research a site that is as close to what Sternberg saw as possible.

We can't miss this scientific opportunity. This is why we need your help. Some of the tracks are exposed, and we know from experience that the longer tracks are exposed, the more likely they are to be damaged by weathering (slow) and human selfishness (fast). We need to get in, uncover, document, and securely cover the site this summer. To do this safely and efficiently we need to replace our old equipment (truck, all-terrain vehicle) and pick up a new item: a secure cargo trailer in which we can store gear (we've had all of our sites robbed) and store specimens. We also need to feed our crew of staff and volunteers.

Once this site is documented, we hope that it can one day be used as a science-based tourism initiative. Our research this summer will be the basis for all of the exciting stories we'll discover about Early Cretaceous dinosaurs. We want to bring the Peace River Canyon tracks from their watery obscurity, if only by proxy, and tell their story to the world.

You can help us tell that story. The most important way you can help is to share the "Research Dinosaur Tracks in Northeast BC, Canada!" site with anyone interested in history, heritage, dinosaurs, and science education. If you have the means, we would greatly appreciate any contributions.

I know we can do this.


References

Currie PJ. 1981. Bird footprints from the Gething Formation (Aptian, Lower Cretaceous) of northeastern British Columbia, Canada. Journal of Vertebrate Paleontology 1(3-4):257-264.

McCrea RT, Buckley LG, Plint AG, Currie PJ, Haggart JW, Helm CW, Pemberton SG. 2014a. A review of vertebrate track-bearing formations from the Mesozoic and earliest Cenozoic of western Canada, with a description of a new theropod ichnospecies and reassignment of an avian ichnospecies. New Mexico Museum of Natural History Bulletin 62: 5-94.

McCrea RT, Buckley LG, Farlow JO, Lockley MG, Currie PJ, et al. 2014b. A ‘Terror of Tyrannosaurs’: The First Trackways of Tyrannosaurids and Evidence of Gregariousness and Pathology in Tyrannosauridae. PLoS ONE 9(7): e103613. doi:10.1371/journal.pone.0103613

Sternberg CM. 1932. Dinosaur tracks from Peace River, British Columbia. National Museum of Canada Bulletin 68:59-85

Friday, April 17, 2015

The Ultimate Reality TV - Live Nest Cams! (a.k.a. Theropods/Birds Do It, Bees Do It)

Hello Dear Readers!

Excuse me while I clear the digital tumbleweeds from my blog. Shaman is in full-tilt writing mode right now: I have two papers with fast-approaching deadlines, and thesis chapters to write. If all goes well, I may be finished my degree by the end of the year.

Be they papers or thesis chapters (also known as future papers), this means I'll be spending a great deal of time at my computer, sitting and writing and drinking more Earl Grey tea than is good for a person. I've mentioned in previous posts that I have a rather distracted part of my brain that insists on being entertained while I'm writing. Since I have neither cable nor satellite (and haven't yet taken the Netflix plunge), and since there are only so many times I can re-watch what I refer to as my writing movies, I have become an unabashed live nest cam addict.

It's not only the up close view of the personal lives of birds, or the rapid transition from a helpless ball of fluff to a fully functioning bird of prey (or of fish, or of flower...) that fascinates me about nest cams: being an unapologetic bird geek, I love being able to spread my love of the avian world around. A peek into the usually secret lives of birds, from egg laying to leaving the nest, and to be able to watch parental care of deadly predators (in the case of our birds of prey), it gives me a sense of connection with nature that I miss when I am office-bound. Teaching, and getting kids interested in the natural world is another interest of mine. Nest cams are great teaching tools, and the Cornell Lab (see link below) provides wonderful tutorials on how to incorporate live nest cams in to biology lessons.

I also have a paleontology interest in the nesting behaviors of birds. Birds are modern-day (or extant, for the technical term) theropod dinosaurs! There is great fossil evidence that theropod dinosaurs also engaged in nest building, active egg incubation, and parental care that is similar to what we see in modern birds. The best example (and best-known science story) of bird-like brooding in theropods is with Oviraptor philoceratops (the egg thief that loves ceratopsians). This story begins with the initial interpretation of thievery to explain its presence on a dinosaur nest full of eggs (thought to be the eggs of Protoceratops), and an associated skeleton of a predatory dinosaur with a toothless beak: both pieces of information led the researchers of the day (Osborn 1924) to suggest that Oviraptor was well-suited - and took advantage of - a diet that included eggs. Norell et al. (1999) examined an oviraptorid skeleton found in a similar position as the original Oviraptor specimen - a skeleton closely associated with a clutch of fossil eggs.

Figure 1 from Norell et al. (1999). Here's a link to the paper. Free to download from the American Museum of Natural History Research Library, along with many others!

The study of eggshell is a sub-discipline within paleontology much like ichnology: by studying the surface and microscopic details of eggshell, researchers can identify which animals laid the eggs. Dr. Darla Zelenitsky is an expert in the study of dinosaur egg shell and reproductive traits in dinosaurs: check out the research page for Evolution of Reproductive Traits in Theropods, and feast your eyes on an image of an oviraptorid skeleton with eggs actually inside the pelvic cavity!

(Note: Unfortunately, there are also many, many theropod eggs for sale online. These mostly come from Mongolia, and they are illegally removed from the country. As I've stated before, buying specimens like these supports fossil poaching and other illegal fossil-related activities. Yes, bad pun alert: the eggs you see for sale online are poached.)

To return to the story of Oviraptor, Norell et al. used the shape and texture of eggs that contained embryonic oviraptorid bone found in different parts of Mongolia and compared those eggs to the eggs found in a nest topped with an Oviraptor skeleton. Sure enough, the morphology of the eggs matched! These Oviraptor specimens did not die in the act of thieving a Protoceratops nest - they were incubating their own eggs. Of course, that does not suggest that Oviraptor didn't ever rob nests of other dinosaurs - modern birds, such as corvids (crows, ravens, magpies, jays), raid the nests of other birds. Food is food. However, what these nests and skeletons do show is that bird-like nest building and brooding are not restricted to our modern theropods - nesting is an old, old behavior for dinosaurs.

There is more evidence of nesting behavior in dinosaurs, but here is a very short list. Varricchio et al (1999) describe a nest attributable to the Late Cretaceous theropod Troodon formosus, and document both the crocodile-like and bird-like traits seen in the nest. The nesting hadrosaurs (duck-billed dinosaurs) from the Two Medicine Formation in Montana are another famous example (Horner and Makela 1979). Nests have also been well-documented for titanosaurid sauropods (Chiappe et al. 2004, for just one example).

Because of the increased information we have on the nesting behavior of dinosaurs, paleontologists are able to examine other aspects of dinosaur reproduction, such as when dinosaurs became sexually mature (check out the Erickson et al. 2007 paper here), and how active hatchling dinosaurs may have been based on the microstructure and development of their bones (Horner et al. 2000). There are even data that suggest Cretaceous snakes may have preyed upon hatchling sauropods: check out the paper and images by Wilson et al. (2010) here. Cretaceous nesting biology was just as complex and fascinating as is modern nesting biology!

If you want to see some modern theropods nesting and raising their young, here are the live nest cams I watch. All of the cams listed here have a bird incubating eggs, young in the nest, or are being actively investigated by potential nesters. This list is by no means an exhaustive list of all live nest cams everywhere - there are nest cams up all over the world, and this list is admittedly Canada and United States focused. If you have a favorite nest cam, please share the link in the comments section, and I'll add it to this list!

Cornell Lab of Ornithology Bird Cams - Here you will find great educational resources for incorporating Bird Cams in to classroom lessons! Their bird cams are:
  • Great Horned Owls, Skidaway Audobon - On air. The owls have fledged, but there are two Osprey that have been visiting the now empty nest. Will the nest be repurposed? Watch and find out!
  • Laysan Albatross, Anonymous - On air! Chick active and growing (with the occasional rooster prancing across the stage). A different kind of nesting strategy - ground-nesting! You also get to see parents feeding the chick, and adults performing display behaviors.

American Kestrel Partnership Bosch KestrelCam - On air, and there may be five eggs in the nest! Kestrels are cavity nesters, and you can find instructions on how to set up a nest box for American Kestrels here.

The Peregrine Fund Peregrine Falcon Nest Cam, Boise, Idaho - On air. Mother is on the nest at this writing. It is not uncommon to find Peregrine Falcons living in urban areas, as these birds of prey are most often seen in a mountain habitat and are cliff-nesters. This is why we find Peregrine Falcons nesting on ledges of tall buildings.

Alessondra's OKC Great Horned Owl-Cam - Great Horned Owls decided that a planter makes a great nest! The nest cam was set up by homeschooling family and used as an educational tool. Off air now that fledging has taken place for the year. Will they return for 2016? [Note: if you watch the farewell video, the starting theme music and sad tones had me worried that the owls had died. Happy Spoiler: they successfully fledged.]

Pennsylvania Bald Eagles, Hanover, Pennsylvania Game Commission - On air, and two chicks (looking quite theropod-y) are in the nest!

Bella Hummingbird's Nest Cam, La Verne, California - On air, and the tiny nest is crammed full of two Allen's Hummingbird chicks!

Happy Nest Viewing!


References:

Chiappe LM, Schmitt JG, Jackson FJ, Garrido A, Dingus L, & Grellet-Tinner G. 2004. Nest structure for sauropods: sedimentary criteria for recognition of dinosaur nesting traces. Palaios 19(1):89-95.

Clark JM, Norell MA, & Chiappe LM. 1999. An oviraptorid skeleton from the Late Cretaceous
of Ukhaa Tolgod, Mongolia, preserved in an avianlike brooding position over an oviraptorid nest. American Museum Novitates 3265:1-36.

Erickson GM, Curry-Rogers K, Varricchio DJ, Norell MA, & Xu X. 2007. Growth patterns in brooding dinosaurs reveals the timing of sexual maturity in non-avian dinosaurs and genesis of the avian conditio. Biology Letters 3(5):558-561.

Horner JR & Makela R. 1979. Nest of juveniles provides evidence of family structure among dinosaurs. Nature 282:296-298.

Horner JR, Padian K, & de Ricqlès A. 2001. Comparative osteohistology of some embryonic and perinatal archosaurs: developmental and behavioral implications for dinosaurs. Paleobiology 27(1):39-58.

Osbom, HF. 1924. Three new Theropoda, Protoceratops zone, central Mongolia. American Museum Novitates 144:1-12.

Varricchio DJ, Jackson F, & Trueman CN. 1999. A nesting trace with eggs for the Cretaceous theropod dinosaur Troodon formosus. Journal of Vertebrate Paleontology 19(1):91-100.

Wilson JA, Mohabey DM, Peters SE, Head JJ. 2010. Predation uponh atchling dinosaurs by a new snake from the Late Cretaceous of India. PLoS Biol 8(3): e1000322. doi:10.1371/journal.pbio.1000322

Thursday, March 12, 2015

Early Bird (Tracks) in British Columbia: Introducing Paxavipes!


Hello, Dear Readers!

It's been awhile since I've dusted off the Blog: it's been a stressful time for the Shaman, and while Tolkien made the apt observation that harrowing tales make the best stories (The Hobbit), I'm bored of thinking about it, and would much rather talk about paleontology! Our research group had a fun time publishing on my favorite subject: BIRDS! Specifically, we have a recent paper in Cretaceous Research on a new avian ichnotaxon (footprint type) from the Peace Region of British Columbia!

Please join me in welcoming Paxavipes (Peace bird footprint, in reference to the Peace Region) babcockensis (in reference to Mount Babcock, the mountain on which the specimen was discovered) to the ichnological family! OK, that's not taxonomically accurate, as Paxavipes is also part of a new ichnofamily. Bear with me.

Bird tracks have been known from British Columbia, and specifically the Peace Region, since their scientific debut in 1981 with Aquatilavipes swiboldae (Currie, 1981). This specimen was recovered as part of the salvage and study operation performed by the then Provincial Museum of Alberta before the completion of the Peace Canyon hydroelectric dam. The area was so well-known for its palaeontological heritage that it was officially designated a Provincial Historic Resource in the 1930s. Today you would need gills and fins (and a whole bunch of de-silting equipment) to see these localities, as they are now underneath what is known as Dinosaur Lake. The type slab for Aquatilavipes swiboldae now resides in the Royal Tyrrell Museum of Palaeontology (RTMP). At the time of its scientific write-up, it was the earliest known bird track type, being from Gething Formation deposits that are Lower Cretaceous (Aptian, approximately 125 - 113 million years old). Since then, no bird footprints have been published on from British Columbia...until now.

The rock slab on which Paxavipes are preserved was discovered in 2005 by a (then) doctoral student Curtis Lettely (University of Alberta). The slab was discovered in an area locally called The Boulder Gardens. The Boulder Gardens is series of hiking trails leading outdoor adventurers through a gorgeous sup-alpine terrain of visually stunning sandstone erosional features. Check out more information on the PDF here. Boulder Gardens is within the boundaries of the newly established Tumbler Ridge Global Geopark. The Boulder Gardens showcases rock from the Boulder Creek Formation, which is Early Cretaceous (middle-upper Albian, approximately 100 to 105 million years old.)

This was an interesting slab. The rock slab was found vertically embedded in eroded rubble and dirt, and what was exposed was covered in many lichen colonies. Lichen is hard, crusty, and hides any surface details it covers. We could see that there were small theropod footprints (Irenichnites-looking prints), and a few visible bird footprints, but did not know how many prints were preserved on the surface, or anything detailed about their shape, with all of that crusty lichen. That lichen had to go...

Fig. 2 of PRPRC 2005.001.015 from Buckley and McCrea (2009). It's easy to see which part of the slab was exposed for lichen colonization.
...but carefully. Lichen is a resistant organism - what else can you expect when fungi and cyanobacteria form an alliance (symbiotic relationship)? Mechanically scraping off the lichen was not an option, as that would have risked mechanically scraping the track surface and the prints it preserved. After trying out a few different chemicals, we saw that a dilute bleach solution effective at breaking down the lichen to a point where it could be gently brushed away with a soft toothbrush. The technique worked so well that it became the topic of my first first-author publication (Buckley and McCrea, 2009).

Once the lichen was removed, the surface was revealed...and what a reveal! A grand total of 72 bird footprints were visible, which enabled us to make out five trackways - series of footprints made by one bird walking from Point A to B. Single footprints are like an isolated bone or tooth - they give us good information, but not as much as a whole skeleton does. Trackways are like the whole skeleton.

Fig. 4 from Buckley and McCrea (2009) So many bird footprints were visible once the lichen was removed!

Another cool "after lichen" reveal was that the small theropod footprints had tiny skin impressions on them! Check out the teeny tiny pebbly texture:
Fig. 6 from McCrea et al. (2015). Skin impressions such as these give us a good idea of what the soles of dinosaurs' feet looked like. These tubercles likely acted like the treads on our running shoes.

Back to the birds. Since we have trackways, we could tell left footprints from right footprints, but not easily. There was something odd with these particular bird footprints. The usual case for bird footprints is that the outer toe is much more splayed away from the middle toe than is the inner toe (or the toes have a roughly equal amount of splay). These footprints were strange in that the inner toe was more splayed than the outer toe. It wasn't just one or two footprints out the 72: it was the majority of the prints.

Fig. 4 from McCrea et al. (2015) showing the holotype trackway - see the wider splay between the inner digits?

Something was up. There is a bit of natural side-to-side wiggle potential in bird toes, and modern bird footprints can show a big differences in toe splay (70 degrees to 140 degrees between the outer digits), but a consistently larger splay between the inner (digit II) toe and the middle (digit III) toe is not common in Cretaceous avian bird footprints. The only other bird footprint type that shows this toe arrangement is Barrosopus slobodai (Coria et al. 2002) from the Late Cretaceous of Argentina. Because these two footprint types are unique when compared to all other Mesozoic bird footprints (but different enough to still be considered separate footprint types), we formed a new ichno (footprint) family of bird prints called the Paxavipedidae. Any new three-toed bird footprint (no hallux) with consistently wider splay between digits II and II than between digits III and IV and thick digits can be assigned to this new footprint family.

As an ichnologist, when I see a repeated footprint shape or toe arrangement within all that natural variation, I begin to think about the shape of the foot. Specifically, I think about the features of the skeleton that made that footprint shape possible. Looking at modern birds, Paxavipes and Barrosopus prints are very close in shape to footprints of the Killdeer (Charadrius vociferus).

I love this image by Ryan Hodnett, found on Wikipedia. No, Killdeer are not some strange Octo-Bird: those are young Killdeer hiding under the parent.
Looking at the foot bones of a Killdeer (welcome to my thesis!), the end of the metatarsals (the lower part of the "leg" of the birds that you see hiding in the above image) are shaped in such a way that the inner toe (when attached) is going to be more splayed than the outer toe! Footprints may not always match the skeletons of feet perfectly, since living feet are covered with skin and muscle. In some cases, like with two-toed dromaeosaur trackways, there are features of the animal's skeleton that are expressed in the footprints. When we find these features, we have a good chance of predicting what the skeletal foot of these track-makers would look like. We haven't yet found the track-maker for Paxavipes, but we have a good chance of recognizing it when (if) it is found! [NOTE: This doesn't mean that Killdeer were around in the Early Cretaceous: this means that a bird with a foot shape that resembles a foot of a Killdeer was around in the Cretaceous.]

Next time you are walking along a beach and see little brown and white shorebirds skittering along the edge of the water looking for yummy invertebrates, think about a Cretaceous shoreline: you would likely notice the dinosaurs first, but the small shorebirds still made quite an impression!

References:

Buckley LG, McCrea RT. 2009. The sodium hypochlorite solution for the removal of lichen from vertebrate track surfaces. Ichnos 16(3):230-234.

Coria RA, Currie PJ, Eberth D, Garrido A. 2002. Bird footprints from the Anacleto
Formation (Late Cretaceous), Neuqu en, Argentina. Ameghiniana 39(4):453-463.

Currie PJ. 1981. Bird footprints from the Gething Formation (Aptian, Lower Cretaceous) of northeastern British Columbia, Canada. Journal of Vertebrate Paleontology 1(3-4):257-264.

McCrea RT, Buckley LG, Plint AG, Lockley MG, Matthews NA, Noble TA, Xing L, Krawetz J. 2015. Vertebrate ichnites from the Boulder Creek Formation (Lower Cretaceous: middle to ?upper Albian) of northeastern British Columbia, with a description of a new avian ichnotaxon, Paxavipes
babcockensis
ichnogen. et isp. nov. Cretaceous Research 55:1-18.