Thanksgiving Field Highlights

Ahh, this is why I love California. Especially my master's thesis field area. These are some tidepools exposed during a minus tide at sunset; Monterey Bay is the body of water to the left of the picture.

Yes... I'll use this to gloat about the election more. I'm happy the denizens of Capitola are happy about it to. You can actually see this paint job on photographs taken from aircraft:http://www.californiacoastline.org/cgi-bin/image.cgi?image=200810789&mode=big&lastmode=sequential&flags=9&year=current
Look at the base of the wall about midphoto, at the left end of the long lawn in the middle of the picture. I love the sunglasses that were added.

Here were some very odd linear features in the wavecut platform, which is an exposure of the Purisima Formation. Linear features such as this have been documented before in a similarly aged sedimentary unit of similar composition, the St. George Formation of Crescent City, in northernmost California. However, there the features were attributed to tsunami scouring by the transport of large boulders up and down the beach, in a direction normal to the shoreline. That is a north facing coast at Crescent City, and was susceptible to tsunamis from earthquakes in Alaska. However, this shoreline at Capitola, CA, faces south; what caused these features will likely remain an enigma.


Here is an atlas vertebra of a small mysticete whale preserved in the Purisima Formation. The atlas is somewhat similar to Piscobalaena and Herpetocetus, and likely belongs to the latter or a similar whale.

I have successfully navigated, conquered, and left the seventh level of hell

As in my first semester of graduate school, which was pretty damn tough, but a challenge nonetheless. In any event, finals are over, and my first real break from it has started... I... don't know what to do with all my free time! Its amazing... Anyway, expect more activity on here than what has been recently.

Happy finals!

Turkey Day!!!

Well, I'm about to leave for Thanksgiving week, and in a few minutes I'll be driving to the sprawling, gigantic Gallatin Field airport here in Bozeman (or should I say Belgrade). Anyway, it only has four gates, and can't service anything larger than a 737 (which it only does during the holidays).

I am super excited, mainly to see my family (who I haven't seen in several months), but also because of fieldwork - I have checked aerial photos, and there has been a LOT of coastal erosion, and it will only get worse (or in my case, better) between now and winter break.

You see, most paleontologists (here at MSU anyway) only get to their field areas in the summer, because its usually too damn cold to do so in the winter (although with a few Miocene land mammal spots around Bozeman, we've gone out in 20 degree weather before, and done jackets in 35 degree weather, with snow on the ground - we were really, really bored.... yeah...).

However, in California, it rarely dips below 45 degrees on the coast (and sometimes rarely above 55 in the winter), so it is possible to go out during this time of the year. However, in the winter, it is not only possible, it is usually far more productive as well. This is due to increased storm activity during the winter, and the increased chance of having cliff collapses (which really suck for the landowners above, who usually have pieces of their backyard now fifty feet lower, but is really good for me!). Also, during the summer the lack of extremely high tides and storms usually allows the cliffs to collect all sorts of dust, grime, and algae - storms during the winter usually clean off all this unsightly garbage, so that you can see clean, unweathered rock surfaces. I cannot begin to explain how much easier and more productive it makes collecting.

It also allows for the researcher to actually see sedimentary structures, and the detail of trace fossils (e.g. spreiten). Anyway, I have a good feeling about thanksgiving break, and a good feeling about winter break this year. Although I have no idea how I can top last winter break - a 40% complete fur seal skeleton (with partial skull), two partial odontocete skulls (one with partial skeleton, and a partial dentary), a 6" long Carcharocles megalodon tooth (aka bigass shark tooth), and a bunch of pinniped bones, bird bones, and shark teeth as icing on the cake.

I'll try to top that. I know I have at least one dolphin skull to excavate. Wish me luck, and Happy Thanksgiving!!!

Fun with volcanic tephra and invertebrates

One of the most useful sources of data with regards to dating a marine deposit are layers of volcanic ash or tephra. Often these can be dated directly, or chemically fingerprinted and matched to a parent body of igneous rock.

In the case of the Purisima Formation, some portions of it have more ash layers than others; Chuck Powell at the Menlo Park USGS tells me the section where this photo was taken has 13 different ash beds.

This ash bed in particular has been correlated with the Putah Tuff Member of the Tehama and Tuscan Formations of Northern California. The Putah Tuff is approximately 3.4 +/- 0.1 Ma, based on radiometric dating.

The problem with finding and utilizing tephra in the first place for dating or for tephrochronology of course is whether or not it gets preserved in the rock record. Ash forms before an eruption as bubbles form near the opening of a volcanic vent during the release of gas prior to an eruption; the magma that forms the material surrounding the gas cools and mineralizes. This mineralized material forming minute walls between gas bubbles then fragments as the eruption continues, and due to the small size (ash is classified by igneous petrologists and volcanologists as being >2mm) these fragments are then carried into the atmosphere via a 'current' of heated air before and during the eruption. Ash can stay in the atmosphere for long periods of time, and can even travel around the globe. Ash beds chemically identical to Yellowstone's Huckleberry Ridge Tuff (2.2 Ma) have been discovered in deep sea cores from the Northeastern Pacific Ocean. Since ash blows with the prevailing wind direction, and the prevailing winds in North America are westerlies, the ash apparently traveled around the earth (if anyone, e.g. Jeanette, has a reference for circumglobal ash deposition, let me know).

Typically, quieter ocean waters preserve ash better, as the ash needs to fall to the ocean surface, and settle to the sediment-water interface. High energy environments on the continental shelf rework sediment too rapidly to preserve discrete ash beds. However, there is also problem with depositing ash below storm- and fair-weather wave base: bioturbation.

Ah, those pesky critters geologists never like to pay much attention to - you know, animals. Well, in this case, geologists will probably like them even less. The problem is that below storm- and fair-weather wave base, bioturbation is insane - in some cases, like in the Purisima Formation, bioturbators effectively completely homogenize the sediment; I would estimate (based on ichnofabric index) that the sediments in these strata have bioturbated over 95% of the sediment, at least as preserved in a 6 km section of cliffs, which are 100-250' high; I'm too lazy to do the math, but that is a real shit load of sediment to churn through - and thats just in 2D - I don't even want to imagine what the actual volume of bioturbated sediment would be.

In the photograph I've posted (finally), you can see the Putah Tuff correlative ash bed. However, there's a twist - below the bed are the trace fossil Ophiomorpha nodosa, which invade sediments below the ash bed (Blue Arrow). These burrows are infilled with ash, and appear white on a brownish sandstone background. More Ophiomorpha nodosa invade the top of the ash bed, but are infilled with brownish sand(Red Arrow); again, there is beautiful contrast here with the brown filled burrows invading white ash.

In any event, those dastardly crustaceans weren't crafty enough to completely bioturbate the ash bed; the ash deposit was most likely too thick to be completely reworked. In all likelihood there is some sort of a preservational cutoff of ash thickness, although this would scale to the effectiveness of the bioturbating regime to homogenize sediment.

Fortunately, ichnofossils are extremely useful for paleoenvironmental reconstructions, so at least there is some information for geologists - not just a bunch of damn invertebrates destroying perfectly good sedimentary structures and ash layers.

P.s. I think I have a much better photo exemplifying this neat sand/ash contrast on a bioturbated contact; if I find it, I will post that as well).

Challenging Field Localities Part I

So, I'm going to start a series of posts on this site, which will be posted periodically. This post series will concentrate on challenging and technical fossil localities which I've dealt with - in the future, I might post about odd challenges others have faced in the field.

So, for the first post, I'll begin with more or less a conclusion/addition to the last post - how the hell my friend Tim got up there, why he went up there, and why I unfortunately followed.

The above photo is a mosaic of four or five pictures I took and later merged in photostitch. You can see a sort of a ramp on the left side, and a spot with some recognizable footprints. The spot with the footprints is the location of a 6-8" wide ledge, with an overhang underneath; at the time I weighed a few more pounds than Tim, even without any field gear besides my rock hammer (which I later tossed down to the beach so I didn't have to mess with it on my slow descent).

The second photo (at left) shows why we went up there in the first place - there is, in the upper right portion of the photo, a concave upward feature, which is about as long as Tim is tall (~6 feet). That is a mysticete whale mandible, and it is in a bonebed; pieces of bones from this bed had 'rained' down onto a 5' wide bench from this bonebed. To the right, the bed dips, and about 200' north intersects with the beach, and is accessible without a 20+' climb up a precarious, dusty, crumbling cliff. If I had my own rock climbing gear, it would be really awesome to rappel down to this bonebed.

Awesome fieldwork picture

Here is a gratuitous field photo I took three years ago; my friend Tim is about 25 feet above the beach or so. I just thought I should post this, as it is a rather awesome picture. I also used a small sliver of this picture for my personal webpage.

Don't worry, If I recruit you for a day trip in my field area, I won't put you through this. He went up there on his own. Maybe I'll post more on scary-ass fossil localities in the future. All these ideas!

Correction...

So, I totally forgot a very important part of the walrus anatomy, which my girlfriend reminded me...

But I'm not going to tell you. Its time for you to play 'which of these is not like the others...'

What's different?

AND, more importantly, does anyone out there (I.E. any of Annalisa's ex-students) have any suggestions on how to improve the reconstruction?

If noone does, then I'll assume my artwork is 100% perfect (as it usually is).

Reconstruction of a fossil walrus

At left is another reconstruction, this time of a fossil walrus, Valenictus chulavistensis. Valenictus chulavistensis was described by Tom Demere, the Paleontology Curator of the San Diego Natural History Museum.

Valenictus is a very odd pinniped, for several reasons. For one, V. chulavistensis (the only well known species of Valenictus) lacks all of its teeth, save the two elongate canines, which are fairly similar to the tusks of the extant walrus, Odobenus rosmarus. Nevertheless, modern walruses do not use their dentition for feeding, so while the disappearance of the noncanine dentition is unprecendented in other pinnipeds, it is not completely unsurprising as modern walrus noncanine teeth are nearly vestigial, so to speak.

Valenictus also has a number of postcranial features that are highly derived; the fore- and hind-limb bones do not closely resemble those of other fossil or modern Odobenidae (walruses). Also, the skeleton of Valenictus is pachyostotic and osteosclerotic (pachyostotic = thick bones, osteosclerotic = dense bones, more or less). This is possibly a ballast-like adaptation for maintaining bouyancy in a warm water environment.

These adaptations are also seen in sirenians. This is probably an adaptation for feeding in shallow, warm waters: the extant walrus feeds on benthic molluscs in shallow (but very, very cold) water, and (most) sirenians feed on seagrass in the photic zone. Valenictus chulavistensis evidently had many of the same feeding adaptations for molluscivory as does Odobenus, and Valenictus thus far has been found in relatively warm-watter settings, based on mollusc and microfossil assemblages. Additionally, other fossils of Valenictus are known from the proto-gulf of California (i.e. the Salton trough), which was hypersaline - this would have made a large, fat animal even more positively bouyant in the water column, a major hindrance to a critter that relies on benthic invertebrates as a food source.

I'll do some more in-depth posts on this fascinating fossil walrus in the future.

Extinct Mako tooth

Just a quick post, with a very pretty picture. Here is a fossil tooth of the "extinct" Bigtooth Mako shark, aka Isurus hastalis. This shark is the ancestor of the Great White Shark, Carcharodon carcharias. (Since Isurus hastalis and Carcharodon carcharias are simply Miocene and extant end members of an anagenetic lineage, Isurus hastalis didn't exactly go extinct, since it is more or less just a morphotype as opposed to a distinct species).

Later on I'll make up a post completely on the Isurus-Carcharodon transition in the Purisima Formation; there is now a fairly good sample size of teeth from the Isurus-Carcharodon lineage from the Purisima, that demonstrate the appearance of serrations and the increase in serration size through time. Oddly enough, you can see a bit of a little depression that the tooth sits in in the rock surface; that is the remains of a hole I dug for a partial fish skull exactly one year prior (spring break 07; this was 08).

This is one of the youngest occurrences of Isurus hastalis. Needless to say, I was pretty damn happy when I found this. Its a damn pretty tooth, and I'll be donating it to the SCMNH this winter break (If I haven't already - I can't recall).

Reconstruction of a fossil mysticete

At left is a skeletal reconstruction I recently did, which was supposed to go in my talk for SVP this year on a bizarre baleen whale named Herpetocetus bramblei. This skeletal reconstruction is based on a referred skeleton of Herpetocetus sendaicus from the early Pliocene of Japan.

Herpetocetus is a very weird type of baleen whale, and I will most likely be posting about some of its oddities in the future.

For example, there is a very odd 'style' of the suturing between the rostral elements (e.g. maxillae, premaxillae, nasals) and the posterior cranium (particularly the frontals). The mandible of this taxon is extremely strange, as is the jaw joint itself (e.g. glenoid fossa), and the auditory/temporal region of the cranium. The postcranial skeleton is, however, fairly normal for a cetacean.

Lastly, most species of Herpetocetus would have been in the ballpark of 4-5 meters in length, while H. bramblei, the largest known species, would have been in the 5-6 meter range. Still, in American, thats about 15-18 feet, for a large Herpetocetus. Most modern mysticetes occur in the 10 meter-plus range (again, 30 feet or more in American). There are a couple of smallish freaks, such as the Dwarf Minke Whale (an unnamed subspecies of Balaenoptera acutorostrata) and the Pygmy Right Whale (Caperea marginata), in the 6-8 meter and 4-6 meter range, respectively.

Another odd feature about fossil mysticetes is the tendency towards small size with respect to extant mysticetes. For one, this could be climatically controlled (large mysticetes are pretty much relegated to cold, nutrient rich waters much of the year). This also, however, could be sampling bias; several authors have suggested that because the majority of fossil mysticete crania are small (e.g. Herpetocetus), then fossil mysticetes probably were all that small (strongly paraphrased). However, the problem with this statement is that the skull of a 90 foot blue whale is over 12 feet long and 6+ feet wide; thats not exactly easy to excavate as a fossil, and not exactly easy to find complete, either.

Size in fossil cetaceans is worth a post all by itself; that'll come later.

Highlights from the Summer 2008 Field Season

While this blog is still in its infancy, I know I can say that most of my field seasons (whether they be summer or winter, or even spring break) cannot be summed up in one blog post.

Summer 2008 is the exception. The majority of summer 2008 was spent in a Calculus II course at College of San Mateo, hoping in vain (well... as I'm now a grad student... not completely in vain anyway) to pass. You see, I took Calc I at CSM the previous summer, and it proved to be a cakewalk, compared to the same class at MSU. At MSU, they use it as a weeder class to get rid of people who are mathematically retarded. In the case of MSU, there are a lot (and I mean A LOT) of engineering students, and our program is fairly strong here (whatever that means; I'll make negative comments about engineers in some other post in the future). So, that translates into a class that attempts to weed out engineering students. That would be fine, except that (GASP!) I am not an engineering student (thank god). You see, myself included, and many, many other paleontology students are plagued with being bad at math (I am actually rather proud that it is not intuitive; I guess I feel it shows that I'd rather think about things than play with a calculator or a slide rule all day [again, I'll save rant for later post]). In any event, Calc I here at MSU was practically impossible for me to pass. So I took it at CSM, and it really, really, REALLY paid off. I got taught the basics, and I passed.

Fast forward to Calc II. Calc II at MSU isn't so bad, but SVP 2007 kinda screwed that up last fall, so I dropped it, and then spring 2008 really kicked ass in Stats 332, without the prerequisite (thats right Dr. Boik, you asshat, I passed). So I expect a not-so-terribly-difficult time in Calc II. WRONG. I show up on the first day, and its this short dude with crazy white hair named Adolf Schender or some shit. Shortest Nazi I've ever met, anyway (and I knew a couple in high school).

He passes out the syllabus, and I shit you not, on the front it has a subtitle called "Student Learning Outcomes." Then, below it, instead of just numbering them, or having bullets, or dashes or something normal, it says SLO1. As in "student learning outcome 1." Then, SLO2, SLO3, SLO4, SLO5, SLO6, and SLO7. What the fuck? Are you kidding me? I don't even remember some of the nazi-ass instructors at MSU pulling that shit, and this was at a goddamn community college. Anyway, the douche (er dude I meant) was a total asshole the entire class, and to summarize it I passed, and ya, so fuck that guy.

Oh, right, fieldwork. So this stupid math bullshit ate up 90% of my time all summer; at least the prior summer (2007) the class got out at 10:30 am, so I could drive out to the coast and actually have a cool life. This summer, however, the class got out at 1; granted, sunset's at 8pm, so I could have gotten 7 hours of work in, but I kinda wanted to be with my family a little bit too, ya know? So I could pretty much only go out on the weekends.

Which is why I only made it out to the coast five times the entire summer; thats usually the number of trips I do in a week and a half. Next summer will be different, where I'll be staying down in Santa Cruz for 3-5 days at a time (master's thesis fieldwork).

So... in the attached photos, you should see a picture of a bone in situ, and a big shark tooth. The shark tooth is none other than Carcharodon carcharias, or the great white shark. The bone is a phalanx from some kind of walrus (possibly a Dusignathine, or double-tusked walrus). Besides these, my friend Kim Wendell found a very nice juvenile Herpetocetus petrosal (i'll be doing several posts in the future about Herpetocetus, fear not). There should also be a couple photos from my field area.

But... that was basically my entire summer. I usually found that amount of stuff in one or two day trips during the winter. It doesn't really matter, because I'll be going back and starting master's thesis fieldwork in a couple months, and will really be able to find some good fossils.

An alluvial fan

This (rather short) post is for my office mate Christina Carr, because she gets off on alluvial fans. This is an alluvial fan I photographed (in action!!!) this summer along the coast of Oregon. Based on the size, gradient, sediment, and geomorphology, this can be characterized as a debris flow fan. You can clearly see abandoned (and more importantly, unvegetated) depositional lobes, in addition to a new channel incision to the left of the old lobe.

2008 Meeting of the Society of Vertebrate Paleontology

Sunday afternoon I victoriously returned from the 2008 meeting of the Society of Vertebrate Paleontology. On saturday I delivered my first ever oral presentation, on the enigmatic/bizarre fossil baleen whale Herpetocetus bramblei.

The presentation was largely a success; the only negative feedback I received was on my "rather unfortunate [if not tragic] choice of font color". Which is a damn good thing, once you really think about it; much of the world's entire discipline of cetacean paleontologists were all there watching my talk, save one american, two italians, and a frenchman. In any event, I only received good feedback on the scientific content of my presentation... which is awesome. Oh, and ya, Michael Novacek was in the front row (!!!). I only cussed once during my presentation, which is a bit of a milestone for me.

Other than the success of my talk, I realized that I had racked up a total of 10 hours of sleep for the entire conference (4 nights); that averages about 2.5 hours of sleep a night. Too many friends were present, that and our broken thermostat in our hotel room that ensured a constant frigid 50 degrees. So when I did return at 4am, I was kept awake by my own shivering.

Besides the lack of sleep, I was rather surpised this year by the amount of time I spent talking 1 on 1 with my "colleagues" (can I actually say that now?) instead of going to other posters or talks. I must have only gone to a couple of dozen talks the whole week, and I averaged 30-40 minutes at a single poster, so I probably only saw a dozen of those. In any event... I am returning from SVP fully energized about research, with new projects (gulp) in hand with new colleagues.

Hello world!

We'll see if I have enough time this semester to make this worthwhile. I hope to at least have one or two posts a week. We'll see, I guess!