New artwork for Fall 2010

Hey Folks,

I'll have some more on taphonomy in the next few days, but before I get to that, I've got some new artwork to post instead. As I've previously alluded to, this has been an absolute heinous semester, even though I've only taken 1 credit in courses. I've spent the entire semester working on several manuscript projects (at least one of which is about to come to fruition; more on that in the coming weeks). Just over this weekend alone, I've received page proofs for my first paper, received final acceptance for another paper, and submitted the revisions for a third paper. Life is good.From left to right: Agujaceratops, Pentaceratops, Anchiceratops, Arrhinoceratops, and adult Triceratops (="Torosaurus").

In addition to all these, I've been busy with several art projects. The longest project (and still incomplete) is a series of cranial drawings of chasmosaurine dinosaurs for Denver Fowler, for his research he presented earlier this month at SVP for his Romer prize presentation.

Agujaceratops mariscalensis for Denver Fowler's Romer presentation.Subadult Triceratops for John Scannella's Romer presentation.

John Scannella, another Ph.D. student here at MSU/MOR, has recently earned some time in the limelight for killing "Torosaurus" (now known to be just the adult form of Triceratops) - although many people over the summer misinterpreted his study as somehow killing Triceratops instead. John asked me back in September to redraw one of Hatcher's beautiful plates of Triceratops for his Romer presentation. Unfortunately, the skull that Hatcher figured lacked a nasal horn, and he needed it to have one... so I drew it with one, and I can only hope that my drawing doesn't make Hatcher roll over in his grave.

Here's the paleontological 800-lb gorilla in the room: formerly Torosaurus, but what has convincingly shown by Scannella and Horner (2010) to simply the adult form of Triceratops, although many unfortunately still cling to the olde wayes of palaeontological research. This was actually for Denver Fowler's talk rather than John's, and is based on a rather complete "Torosaurus" skull here at Museum of the Rockies.
This I just did for fun over the summer - I actually did this up at Lake Tahoe (and only took about 3 hours, even though it's about two feet wide) while I was on vacation there over the summer. This I believe is some kind of Diplodocus. Some dinosaurs are pretty, although in many cases I could care less which one it actually is. Drawing sauropod dinosaurs is OK, because they're almost as big and almost as cool as a baleen whale. Sorry dinosaur fans, they just never quite made it, but they get an A for effort.Lastly, this is one of my most recent drawings - this is part of a big bird bone. But that's all I'll say for now; I only put this up here because its a good example of a specimen drawing I've done. This one only took about 4 hours.

Anyway, time for shameless self promotion: I auctioned a bunch of prints off at the SVP benefit auction earlier this month, and made a total of ~350$ for the auction, which, according to Denver F., is something like 1.7% of the entire proceeds from the auction. That feels pretty damn good on multiple levels- for one, just knowing that I helped raise that much money (and it only cost me about six bucks to print all that stuff out, including the plastic sleeves) and two, that it was because people liked my artwork and were willing to bid anywhere from 30-80 bucks for prints. Unframed, unmatted prints in a plastic bag.

Anyway, due to the overwhelmingly positive reaction I got for my artwork at the auction, I recently started an account on ETSY.com so that I can try and sell some prints of this stuff, and be able to afford food, and gas, and things that are usually denied to graduate students. I'm just kidding about that, but being able to make a few bucks off doing what I love would be pretty fulfilling. Anyway, if you're interested, go ahead and take a look at my Etsy account.

SVP 2010: barnacle and sea lion taphonomy

Hey Folks, I know it's been a while (I feel like I say this a lot...), but I've been really, really busy. The semester has been really busy - I've been working on four different papers since I got back to school - but postings will be much more frequent for the remainder of fall. The entire month of September was spent writing a new manuscript, and getting revisions done for a manuscript that is most likely accepted for publication in the Journal of Vertebrate Paleontology. The last week of September and first week of October were spent coding characters for a poster I had with my good buddy Morgan Churchill and his advisor Mark Clementz (on pinniped phylogeny), my own poster, and two art projects I was involved with for two of the Romer Prize Presentations at SVP (by MOR/MSU students Denver Fowler and John Scannella, who between the two of them requested 9 or 10 drawings of ceratopsid skulls).Barnacles!!! (not that you've actually read about them yet). Isn't that cool?!

Six days before SVP started, I finally got the chance to work on my own poster, titled "Barnacle colonization of Middle Pleistocene Sea Lion (Carnivora:Pinnipedia) bones elucidate the biostratinomy of a fossil marine mammal". And no.... this is still not part of my thesis, although it is very similar to what I am doing. And actually, getting the poster done and now recapping on it have really helped me get reinvigorated about my thesis; I consider any time spent thinking about taphonomy is more or less time spent toward my thesis. Because this week I am starting to devote 100% of my research time to my thesis, more of my future posts this fall will be taphonomy related (and specifically marine vertebrate taphonomy, one of the most understudied and underpublished aspects of taphonomy).
But enough about my thesis. It's time for barnacle-on-bone action.

My poster from SVP (locality information is blocked out).

I had my poster presentation on Monday, day two of SVP, which was comforting because marine mammal talks and posters are usually the very last day of SVP, and during the afternoon at that (late afternoon/evening if you give a poster!). Anyway, a couple of years ago (June 2008) I was prospecting a marine Pleistocene locality in Oregon and found a couple of bones in concretions - no big whoop. Because of that, I didn't do anything with the bones for about two months, until I set 'em down in my parent's driveway and sprayed them down with a garden hose. As the soft outer rind of sediment began to wash away, I saw little white things I quickly identified as minuscule barnacles. Due to the library of papers on marine vertebrate taphonomy I've amassed for my thesis, I did a quick mental search, and quickly realized that these had never been reported as encrusting bone before. This made me really excited.

A beautiful sea lion femur with barnacles only encrusting one side.

A less cursory glance at the literature shows that these associations have indeed been recorded before in the literature, but never figured. Two examples have been figured, but either the photos are so god-awful or the item in question probably isn't even a barnacle. Otherwise, it's been mentioned as a sentence (or a part of one) before here and there. There are plenty of examples of modern barnacles encrusting old bones: I see that almost on a daily basis in the intertidal zone in Santa Cruz. To clarify, these are fossil barnacles.

The specimen where I first saw the barnacles.

So, into the nitty gritty. There are 1400+ barnacles distributed over three ones (the femur had ~200, and one of the two vertebrae is hogging 700+ to itself). They appear to be of two size classes: big ones (4-7mm with a few outliers) and small ones (~1-2mm). The big ones do not occur on any articular surfaces or in the neural canal, and predominantly only on the neural arch (i.e. few on the centra). The small ones occur pretty much everywhere, and in many cases are growing on the bigger ones. This indicates at least two colonization events. Dr. R. Van Syoc at California Academy of Sciences was gracious enough to identify the barnacles for me over the summer; they appear to be cf. Hesperibalanus hesperius. It is a species that is still extant, and is a prolific fouler of shells.

Closeup of the neural arch (left) and transverse process of the vertebrae (right).

Another interesting tidbit is the presence of barnacle attachment scars: here they are on the bone as oval-polygonal shaped traces, that are only excavated along the periphery. This has been reported before for rocks and invertebrate shells, but not bone.

So, what else can we infer? Because we know the ontogeny of modern Hesperibalanus hesperius, we can reasonably infer a gross estimation of minimum time averaging (i.e exposure time on the seafloor), given the barnacle size (basal plate diameter). The modern species only has a lifespan of 7 months, and seeing as none of these are full grown, they probably only represent 2-4 months. This is, however, assuming that barnacle basal plate diameter is constant: it is well documented that crowded barnacles only achieve a certain diameter until their basal plates are all touching and cramped (such as many on these specimens). So, it is possible that some of these were full grown, and so a time of ~ 2-7 months or so, ballpark.

The lack of any barnacles on some surfaces suggest that the surface was uninhabitable due to being smothered in sediment, or by the adherance of tissue. The femur lacks barnacles on the distal condyles, strongly suggesting the retention of articular cartilage there. Also, the femur only has barnacles on its posterior side, suggesting that the anterior side lay in the substrate and was never flipped. On the contrary, the vertebrae have barnacles more evenly distributed, so that it would be difficult not to smother barnacles at any position the bone was situated at. This suggests that the fossil was rolled around on the seafloor frequently enough to keep individual barnacles from smothering, very similar to the balanulith concept recently published in Palaios and Palaeontology. Anyway, there's much more to type about, but you'll have to wait for the paper, lest I retype everything on here.

On another note, I just got a paper on taphonomy (unrelated to this, but slightly related to my thesis) accepted in publication for Palaios, so you may be able to hear about that sometime early next year, perhaps.

Herpetocetus skull #3, part 3 - Excavation, Day 2

The next day I returned to the locality, and with the help of my buddy Chris Pirrone, we finished undercutting the pedestal; due to the extreme cohesiveness of the sediment, we were able to undercut the pedestal by 3 inches on all sides - which is generally a rare opportunity; with many other fossiliferous units I've worked in, the side of the pedestal would collapse or calve off into the trench.
Within two hours of arriving, we were ready to begin the jacketing process. Above, you can see the top jacket.

Here's a view from the top of the cliff of the plaster jacket and the hole. You can definitely see that with the size of the hole, I was prepared for something sticking further into the cliff.
Soon after, we flipped the jacket over and I began removing excess rock from the base of the pedestal. After removing several inches, I used a jigsaw to cut off the plaster 'lip' that was left from the base of the pedestal.
Chris Pirrone, with the jacket.
And finally, myself with said jacket. I have more pictures of the completed jacket, but they would give away the location, which I'm not terribly keen on doing. All in all, this excavation totaled about 8 hours. By comparison, the well preserved Herpetocetus bramblei skull I collected nearby in 2007 took about 12 hours of excavation, and four hours of jacket transport. Thanks to the much more convenient location of this fossil, jacket removal and transport took a total of two and a half minutes; the tide was way out, so we were able to walk (comfortably) with the jacket to a conveniently placed set of stairs, and then up. The battle Chris and I waged in July 2007 to get the other Herpetocetus skull off the beach is quite a story, and one that I don't think I've detailed here previously.

Anyway, as I probably already mentioned, this specimen includes the first complete rostrum of
a Herpetocetus ever collected, and will feature prominently in my future studies of this enigmatic fossil mysticete.

Herpetocetus skull #3, part 2 - Excavation Day 1

Unfortunately, when I discovered this fossil in its mutilated state, it was two days before I planned on driving back to MSU at the end of the summer, and my last scheduled day of fieldwork for summer 2009, so it was absolutely out of the question to excavate the fossil then. So, I had to return sometime to excavate it. I didn't have the option of doing so over Thanksgiving, Winter, or Spring Break, so I waited a whole year. As it turned out, not much erosion had occurred locally over since initial discovery; just to make sure, I'd visit the fossil every couple of weeks.

I finally had the time to excavate it in mid August; I had some ambitious plans for my last week of summer in California: Saturday and Sunday up at Lake Tahoe, monday and tuesday excavating the fossil, wednesday at the Santa Cruz Museum of Natural History, Thursday at California Academy of Sciences, Friday at University of California Museum of Paleontology, packing up my car on Saturday, and Sunday thru Tuesday on the road.I found out a couple days before hand I would be able to enable to enlist the help of my longtime friend and avocational paleontologist, Chris Pirrone, a local attorney in the San Jose area. Chris helped me excavate the first Herpetocetus skull (which, if you attended my SVP talk in 2008, was the focal point of that research), and has helped me with a few other excavations in the Santa Cruz area.On Monday I was all by myself removing overburden. Surprisingly, after only about four hours of chopping at the cliff face with a railroad pick, all the overburden was gone. So, I started to carefully remove rock an inch at a time by tapping my clam knife with a rock hammer. Eventually, I found the premaxillae, and was able to determine the angle the rostrum went into the cliff (and, more importantly, the fact that the rostrum did in fact exist). If the rostrum paralleled the cliff face, then it would make for an easier excavation, as I would not need to dig as large a hole. Unfortunately, the rostrum dove in there pretty steeply. Here's what it looked like after the first day of the excavation: admittedly there's not much there - and that's exactly the way I prefer it for an excavation. The more fossil bone you expose during the excavation, the higher the chances of damaging that bone. So it's important to figure out during an excavation what the fossil is, which way it's oriented, and roughly where each feature should be; surprises during excavations are usually made by damaging bone.

I've outlined in red the anterior portion of the rostrum (premaxillae are the skinny medial elements, while the maxillae are the wide lateral elements). I exposed some bits of the premaxillae here and there, but just enough to know 1) the angle of the skull going into the cliff and 2) the tip of the rostrum. Oddly enough, the midline of the rostrum didn't match up with the midline of the skull exposed in the cliff. As it turns out, there was a fracture running obliquely through the rostrum - you can see it, near where the red lines end. It's actually offset by about five or six inches.

To be continued...

Herpetocetus skull #3, part 1 - tragedy and mutilation

Hey folks,
Sorry for being absent over the last month or so; I've spent an inordinate amount of time up at Lake Tahoe with my family (i.e. ~5 trips totaling over 1 month) and the rest of the time I spent collecting thesis data and fossils in Santa Cruz, and working on manuscripts. With regards to the latter, I received preliminary acceptance of two different manuscripts in the space of one week; you'll hear more about these papers later. In mid-July, I wrapped up a manuscript I've been working on for 5 years; I decided I was finished with it, and submitted the damn thing. Within the same day, I re-submitted a manuscript for Palaios that was returned for major revisions. And about a week later, I received preliminary acceptance of a paper for JVP on Plio-Pleistocene fur seals (which had only been in review for a month and a half, and another month for the editorial decision, which must be some sort of world record for JVP).

One of my many projects this summer was to collect and excavate a small mysticete skull I had discovered on my last day of fieldwork last summer (2009). Here's what I saw in the field:
Difficult to make out what it is? Well, I had seen this before, but it was covered up with algae, and I just thought it was a concretion. I want you to look at this picture again, and look for all the broken, mutilated bone in the "trench". Done? Now, I've labeled relevant anatomical structures on the same photo, below.
1= Left zygomatic process of squamosal; 2= foramen magnum; 3= right occipital condyle; 4= supraoccipital shield; 5= left supraorbital process of frontal. Yes, that was a complete mysticete skull, keyword: was. I cannot begin to explain how pissed off I was when I saw this. Even worse, then I realized that I recognized that morphology from somewhere:Yes, it was a complete skull of Herpetocetus bramblei. Here's my beautiful specimen from nearby (which was actually collected properly).

So, I don't know who committed this crime, and I don't want to know who it was. I know who it wasn't - I know a half dozen very experienced, extremely competent amateur collectors in the Santa Cruz area who would have never done something this awful to a fossil. I'm not going to use this as an opportunity to scold, though it would be completely warranted. Instead, if you're reading this - let this serve as a plea:

Please don't do this. There are people who can help. I would love to teach you correct excavation methods. This fossil is now mutilated, and the braincase is completely destroyed, and those features and anatomical data are now lost forever. You can still get help. Please, if you find something like this in the future, just ask someone - I'm perfectly happy to help collect it without destroying the fossil or parts thereof.

Additionally, other collectors who do not know me, or if you don't even do collecting in California, it doesn't matter where you are or the color of your fossil: please avoid this at all costs. There are plenty of people willing to help you. Just please, please back away from the edge. I mean fossil.

Beach panorama

Beautiful sunsets can often be seen along the California coast, especially during the winter. This is about eight photos spliced together; although some weirdness happened due to the waves, it looks alright.

Scotts Valley whale excavation, part 2

Before I continue, I need to give a shout out to Nick Pyenson - Nick initially forwarded Dr. Smith's emails to me, and this project has wasted a third of my summer. No, but seriously, thanks.

After putting the top jacket on, then came the problem of how exactly I was going to A) undercut it and B) actually flip it over. Normally, a trench is cut and then the pedestal is undercut from all sides leaving a pillar of rock underneath, which you can subsequently eliminate and then flip the jacket over. However, this jacket was far too large to do conventionally. And I couldn't really fit tools in all the way around the jacket to really undercut it from all sides.

So, in cases like this, go tunneling! I started two holes and dug and dug until they connected, and then widened them into a larve cavern underneath, and then added a hole on the other side. Problem was, this jacket was so large, I eventually couldn't reach the back wall with my rock hammer, and had to use my large estwing pick to scrape away underneath. Tunneling, by the way, is a good recipe for bloody knuckles.

Here you can see more of the tunnel. Aside from these two small columns, the back part remained as a large pedestal in back; the jacket stuck out from this like a surfboard with two pillars. Once I cut the pillars, I figured it would break the pedestal, and tilt forward.
The moment of truth! This was on the heavy side. Well, nothing happened - the left pillar remained still, but I figured it would fail if given this much weight. Apparently not, however - it just hung like this for several minutes.

When I cut through the other pillar, it shifted almost imperceptibly forward, but I knew at that instant that I had been successful. Then, I found one of the construction workers to help me flip it over and complete the jacket.Here's what it looked like - you can see the overhanging plaster; that's where the crack formed, leaving a little bit of the pedestal back in the hole, which I'll excavate in a separate jacket.

Voila! Here's the completed plaster jacket. It's pretty heavy.