Saturday, February 25, 2012
We're still trying to work out the details of what time it is exactly when we land so we can arrange for a ride - both my advisor, Dr. Fordyce, and fellow student (and new father) Gabriel Aguirre-Fernandez have offered to pick us up from the airport.
Anyway, what this most likely means is a blog blackout for the next week or so; I've got a really, really, really long checklist of research stuff to take care of by next saturday, so you can expect some posts once we're in a different hemisphere.
Friday, February 17, 2012
An articulated baleen whale vertebral column sits in a multiton block in the foreground, with Kirk and I looking for smaller fossils in the distance. Photo courtesy Ray Troll.
One of the most notable series of fossil localities are exposures of various strata in the Newport Embayment (a geological basin), including the Alsea Formation, Yaquina Formation, Nye Mudstone, and Astoria Formation. The eccentric, extraordinarily gifted, and tragic figure Douglas R. Emlong amassed an incredible collection of marine mammal fossils from this area and elsewhere in the Pacific Northwest during the 1960's and 1970's, prior to his premature death in 1980. One of the purposes of our trip is to visit several of Emlong's famed fossil localities as a pilgrimage of sorts, and pay homage to the great collector.
Douglas R. Emlong, with the partially prepared skull of USNM 215068, a male skull of the early walrus Proneotherium repenningi. Presumably this is during preparation in the Paleobiology Department at the Smithsonian Institution, during one of his visits to the east coast museum. From "The Ore Bin".
Previously, in October, I met up with Ray and Kirk when they were in California for a week. We took a day trip down to Santa Cruz where I showed them some fossil localities, and all in all had a rather nice day – although I didn't find a damn thing (thanks to there being little erosion over the prior 20 months). As it turns out, Ray and Kirk have increasingly been picking my brain for details on fossil marine mammals from the eastern North Pacific, and I am pleased and excited to help them with their project; most popular books on paleontology deal with dinosaurs, and very few have ever really touched the subject of marine mammals (Neptune's Ark by David Rains Wallace is an exception). Needless to say, I am very excited for their project to take off.
I found out that if the first fossil locality you go to is kind of ugly and has few fossils (but used to have a lot...), Ray Troll will make you pose with the crappiest fossil you find and a bunch of garbage he finds laying about. Included is a toothbrush, a cardboard mayan calendar, a random photo album (yes, we looked through it) and some other odds and ends; I'm pointing to a rather unassuming scrap of sea cow (Dusisiren jordani) bone. True story.
Wednesday, February 15, 2012
When we received the prepaid return envelope in the mail, I saw that it was from the consulate, and when I opened it up - I thought something terribly wrong had happened, because all I saw in there were our two passports. No "congratulations" letter, or alternatively, no "sorry, you can't travel to our country" letter. I had forgotten that the visas are just stickers inside the passport, so I was pretty happy to see not one but two passports with visa stickers inside.
We'll be flying out the first week of March, and have also finally figured out shipping. We've discovered that in order to ship a few hundred pounds of cargo, it is cheaper to pay for an extra two checked bags per person than to try and ship that material in boxes. I am excited as hell to get down there and start exploring and starting my dissertation research, and joining I'll be joining Dr. R. Ewan Fordyce's group of Ph.D. students (in no particular order) Gabriel Aguirre-Fernandez, Carolina Loch, Felix Marx, and Yoshi Tanaka.
University of Otago Department of Geology
Wednesday, February 8, 2012
During my freshmen year of college, I was interested in doing some sort of a field-based research project, and after showing my advisor - Dr. Dave Varricchio, who was in his first year of being a professor at Montana State University - a bunch of fossil shark teeth I had collected and identified from Sharktooth Hill and from the Santa Margarita Sandstone in Scotts Valley, he began to encourage me to pick an area to look at. Originally, I had two ideas: the first was Sharktooth Hill; I had been in contact with Dr. Joyce Blueford, a foram paleontologist who runs the Math Science Nucleus program in Fremont, California, and she had done fieldwork at the early Pleistocene Irvington Gravels in the 1960's and 1970's, and my second idea was to reopen field work at the Irvington gravel pits. There is still a lot of unpublished material from Irvington currently housed in UCMP collections; the last study which described a wide array of its fossils was published by Donald Savage in 1951, and Chris Bell has done some more recent work on rodent teeth from the locality.
Every summer, most of the members of my family congregate on the beach at Lake Tahoe for a week for an annual family reunion; I have quite a few cousins, and it's something we all look forward to every year. This one day in late July, 2004, I received an excited phone call from my uncle Robert, who is a blacksmith (ferrier to be exact) and surfer, and some surfer friend of his had told him about a "skeleton in the cliff near Santa Cruz". By that point in my field career, I was fairly familiar with Santa Cruz, but had not been to every locality, and was not surprised I had "missed" something. I wrote down the contact number, and patiently waited another week until we were back in the bay area so I could make it out to the coast. I got my high school buddy Tim Palladino and we drove out to the coast, after calling the surfer and getting directions; it was the surfer's son who had made the discovery, and even after explaining several times that given the location he described - it was most likely an outcrop of the Purisima Formation, and therefore marine, under 6 million years old, and probably of a whale - the poor chap asked me like seven times if it could be a dinosaur. I calmly explained that dinosaurs went extinct 65 mya, and that the fossil he found - if it were even a fossil - was at most a fraction of that, and not possibly a dinosaur. To which I heard "Uh, are you sure it's not, like, a dinosaur?" - so I just thanked him politely, and drove on.
Upon arriving at the locality, we found precisely where he had indicated; there was a narrow and muddy trail out to a point of rock, and then a rope dangling from a rusty piece of rebar stuck in the soil, which we were supposed to use to climb up onto a ledge, from another ledge below the promontory - which was already twenty feet above the beach - and then the fossil was about ten feet down. We thought 'to hell with that', so we continued to look around; it didn't take us more than a few minutes to start finding bone, and we found quite a lot of it, and quickly. I realized that this locality had some serious promise, and better yet - was completely unstudied and nearly completely unknown with respect to its vertebrate fossils. In fact, aside from a couple of fragmentary bones in UCMP collections that had been picked up by a private collector in the 1970's - only mollusks had been collected from the locality.
In June, 2005, I was up at a remote lake in the Sierras near Emigrant Gap, volunteering as an adult leader for my old boy scout troop doing their annual 'base camp' camping trip; it was a good excuse to hang out around the campfire with my brother (still in the troop) and a couple of our friends. I had not yet heard anything about the permit, so I thought I'd take a canoe and head to the dam side of the lake, and hike way up on this one hill that gets cell service, and check my voice mail (nobody else knew there was anywhere with cell service, but I had camped there in 7th grade and I remembered the spot my friend's dad found). I had one message from Dave Varricchio, in which he shared some reservations about the permit after speaking with the permitting official on the phone; I called him from the mountainside, explained a few issues, and he agreed to convince the official I was OK for the project. Looking back, I can completely understand: it's relatively unheard of for an undergraduate student to apply and receive a collecting permit, and I would have been nervous as hell if I were in Dave's shoes then. For whatever reason, I wasn't getting along with one of the fathers on the trip, and a couple days later, once again set out by canoe to the other end of the lake nearly a mile away to make some phone calls; I decided to leave the next day (three days before the end of the trip), and my friend trim and my brother paddled out again with my backpack. It wasn't on Interstate 80 before I got a call from my parents (who I would stay with during the summers), informing me that my permit had arrived in the mail - I was thrilled - my first permit had been granted! I rushed home, and within a couple days was out at the locality showing an ecologist around to the various "big" specimens that would require some site disturbance during excavation.
I spent nearly a full week out there - driving to the site each day, of course - and met Frank Perry of the Santa Cruz Museum, who acted as my technical advisor for the project; I walked Frank through the various localities, and he instructed me to pay close attention to the mollusks. One thing I have not yet mentioned is the age of the locality - previous age determinations had widely varied. Originally, based on mollusks, the locality was considered to be latest Miocene in age. However, there was a thick ash bed in the section that was chemically fingerprinted and correlated with the Ishi Tuff member of the Tuscan Formation in Northern California. Volcanic ashes, if not datable, can be chemically compared with parent volcanic rocks formed directly from cooling of lava from the same eruption of volcanic event - most times, volcanic ashes and parent volcanic rocks are chemically unique (my guess would be due to whatever crustal rocks the volcano had to "burn through" in order to erupt), hence the term "chemical fingerprinting". In this case, the Ishi Tuff is only 2.5 Ma, in start contrast to the mollusk biostratigraphic age estimate of 6-8 Ma. My study, if ample vertebrate fossils were discovered - could test these dates independently, as neither determination involved vertebrate fossils. Vertebrate fossils, although only useful in a crude sense for biostratigraphy (with the exception of some periods of time with land mammal fossils), could probably distinguish between late Miocene and late Pliocene, however.
The other sharks are all represented by teeth and dermal denticles, and include great white sharks (Carcharodon carcharias), mako sharks (Isurus oxyrhinchus), basking sharks (Cetorhinus maximus), cow sharks (Hexanchus sp.), a sawshark (Pristiophorus sp.), an angel shark (Squatina sp.), a hammerhead (cf. Sphyrna), and a separate great white from the base of the section (Carcharodon sp.). The Carcharodon from the base of the section had very tiny serrations, while the Carcharodon specimens from further up in the section looked more like extant Carcharodon carcharias with coarse serrations. The modern great white evolved from the mako shark Cosmopolitodus (=Isurus) hastalis; indeed, serrationless Cosmopolitodus hastalis are known from the base of the Purisima Formation, while Carcharodon sp. teeth with minute serrations occur in the middle, and modern looking Carcharodon carcharias teeth occur near the top (late Pliocene). With the exception of serrations, the shape of Carcharodon and Cosmopolitodus hastalis teeth are identical, and this has been determined by statistical analysis of tooth shape (Nyberg et al., 2006). This is in stark contrast to the older hypothesis that modern great whites share some form of nebulous phylogenetic relationship with the "mega-toothed" sharks of the genus Carcharocles (i.e. Carcharocles megalodon, which under the older hypothesis would be regarded as Carcharodon) that has yet to really be defined properly and supported statistically or by stratigraphic studies of sequential shark tooth assemblages demonstrating gradual change from one tooth type to the modern. Instead, analysis of Carcharodon and Cosmopolitodus teeth from various well dated stratigraphic levels of sequentially younger ages from the Pisco Formation in Peru (Muizon and DeVries, 1985) first documented this gradual transition in serration development through time. This transition has now been documented in Peru, Japan, and elsewhere in California.
A few birds were also collected during the study - my first bird bone ever, a humerus of the flightless penguin-like auk Mancalla, was collected in August 2006. This turned out to be from the species Mancalla lucasi (which is sort of a replacement name for the size taxon Mancalla diegensis, which was originally named off of a femur, which is morphologically conserved in Alcidae - I'll cover Adam Smith's recent Mancalla monograph in a subsequent post). Additionally present was a previously collected humerus of a large gannet, Morus sp.; gannets do not live in the eastern North Pacific today, and there are numerous Pliocene and Pleistocene fossils of Morus, indicating a relatively recent extirpation of them locally. Also collected was a pretty dang big pedal phalanx (see 5-6, below) which I now suspect is a Pelagornis phalanx; also, that huge Pelagornis humerus (Boessenecker and Smith, 2011) was discovered at this locality as well. A couple of bony fish were present, including a tuna (Thunnus sp.) and a large flounder (Paralichthys sp.), based on vertebrae.
So, what did the vertebrate assemblage indicate for the age of the unit? Well, Mancalla lucasi is only known from middle and late Pliocene strata, for starters. The other bird, Morus, is known back to the middle Miocene, and of absolutely no use. Furthermore, the presence of Carcharodon with coarse serrations was also indicative of a young age. Carcharodon is restricted to the Pliocene, except in a few cases where it is from just below the Mio-Pliocene boundary or are from poorly dated rocks, or from dubious antiquated literature. This indicated that the base of the section, which already had Carcharodon that was more plesiomorphic and probably older - was already likely to be Pliocene in age. Additionally, the distinctive skate jaw cartilages have only been found in Pliocene sediments. All of this evidence pointed toward the ash date of 2.5 Ma to be correct.
As it turned out, while I was writing this, my colleague Chuck Powell at the Menlo Park USGS published a huge paper on Purisima Formation stratigraphy (Powell et al., 2007), and they recovered a diatom flora from the base of the section indicative of a latest Miocene to earliest Pliocene age (6.4-5.6 Ma), and another date from an ash below the aforementioned deposit which correlated with a 3.35 Ma volcanic unit. Altogether, the new data meshed well; in the end, the mollusk age determination turned out to be sort of right, although many of the mollusks were misidentified or too poorly preserved to be identified properly, and there aren't any mollusks actually preserved in the section that is that old (Powell, 1998). Additionally, I found the large scallop Patinopecten healyi at the locality (which had also been collected previously), which is a Pliocene index fossil.
The paper eventually took the long winded title "A new marine vertebrate assemblage from the Purisima Formation in Central California, Part 1: fossil sharks, bony fish, birds, and implications for the age of the Neogene Purisima Formation west of the San Gregorio fault." This paper took me about five years to write, and was my first manuscript I started; Chuck Powell went through I think four drafts before I decided it was good enough. I spent a bit of time during my second year of grad school revamping an older, piece of crap draft - a week of late nights in the graduate student office at MSU, literally cutting a printed copy into pieces and rearranging the better "chunks" into coherent sequences of more meaningful words, and scribbling out terrible sections with a red pen. In summer of 2010, I finally got the courage up to finish it, setting a deadline of one week - and miraculously, I finished it in 5 days. Getting rid of this manuscript and seeing its publication has been one of the more meaningful and satisfying endeavors of the past few years.
Since June, I have been furiously working on "A new marine vertebrate assemblage from the Purisima Formation in Central California, Part 2", and I am pleased to report that it is nearing completion. I have one skull left to finish preparing and to describe, about ten figures left, and some reviewing, a couple gaps to fill in, and finish peppering the manuscript with citations (and add them into endnote). As of late last night, the manuscript is now 139 double spaced pages, nearly twice the length of Part 1, and it will likely grow another 10-20 pages. There are now 30 marine vertebrate taxa from the assemblage. Publication of Part 2 will be the first time a marine vertebrate fossil assemblage from the western United States has been described and published in its entirety (with the possible exception of Sharktooth Hill, which by the time Remington Kellogg described the marine mammals, nearly the entire known assemblage had been published upon, although now only a fraction of the marine mammals are published due to a backlog of unstudied material at LACM and UCMP).
Boessenecker, R.W. 2011. A new marine vertebrate assemblage from the Purisima Formation in Central California, Part 1: fossil sharks, bony fish, birds, and implications for the age of the Neogene Purisima Formation west of the San Gregorio fault. PalArch's Journal of Vertebrate Paleontology 8(4):1-30.
Boessenecker, R.W. and N.A. Smith. 2011. Latest Pacific basin record of a bony-toothed bird (Aves, Pelagornithidae) from the Pliocene Purisima Formation of California, U.S.A. Journal of Vertebrate Paleontology 31(3):652-657
Muizon, de, C. & T.J. DeVries. 1985. Geology and paleontology of late Cenozoic marine deposits
in the South Pacific (Sacaco area, Peru). – Geologische Rundschau 74: 547-563.
Nyberg, K.G., C.N. Ciampaglio & G.A. Wray. 2006. Tracing the ancestry of the great white shark, Carcharodon carcharias, using morphometric analyses of fossil teeth. – Journal of Vertebrate Paleontology 26: 806-814.
Powell, II, C.L. 1998. The Purisima Formation and related rocks (Upper Miocene- Pliocene), greater San Francisco Bay Area, Central California. Review of literature and USGS collection
(now housed at the Museum of Paleontology, University of California, Berkeley). – US Geological Survey Open File Report 98-594.
Powell, II, C.L., J.A. Barron, A.M. Sarna-Wojcicki, J.C. Clark, F.A. Perry, E.E. Brabb & R.J. Fleck. 2007. Age, stratigraphy, and correlation of the late Neogene Purisima Formation, central
California coast ranges. – U.S. Geological Survey Professional Paper 1740.
Smith, N.A. 2011. Taxonomic revision and phylogenetic analysis of the flightless Mancallinae
(Aves, Pan-Alcidae). – ZooKeys 91: 1-116.
Friday, February 3, 2012
Eventually we reached Santa Barbara, and went to visit the small and quaint Santa Barbara Museum of Natural History; historically speaking, there are two important vertebrate fossil specimens at the SBMNH: the holotype of the early Late Miocene walrus Imagotaria downsi, and the holotype of the gigantic bony toothed bird Pelagornis orri (originally Osteodontornis orri, and also from the same stratigraphic unit - the Sisquoc Formation - as Imagotaria). Previously, at the LACM, Morgan and I had examined casts of the Imagotaria downsi holotype, which I assume is back at the SBMNH collections. After our visit, we stayed the night in the quaint and adorably bizarre Danish-themed hamlet of Solvang, California (did you get the double entendre?). From there, we spent another day up the coast driving through Big Sur, concluding the trip (meaning I had to get back to work).
Above the slab and counterslab, a painted life size reconstruction of Pelagornis orri hangs on the wall, giving visitors an idea of how absurdly large these birds were. And Pelagornis orri is one of the smaller species of pelagornithids; the specimen that Adam Smith and I published would have been even larger, closer to the size of Pelagornis chilensis.