Monday, July 30, 2012

More photos from Purisima Formation field work, 2

 We were stuck behind these jerks riding three abreast for about 5-6 miles.

 Tule Elk! After many years living in southwestern Montana, I was surprised to learn that elk of this subspecies (Cervus canadensis nannodes) are the largest by body mass in North America; Northern California is also home to the smallest subspecies, the Roosevelt Elk.
 Small individuals of the giant green anemone (Arthropleura xanthogrammica) on an exposure of the Purisima Formation.

 A starved California Sea Lion (Zalophus californianus) yearling on the beach.

 It was very strange to come across a tarantula on a beach, within a couple hour's drive of San Francisco.

 A bunch of harbor seals (Phoca vitulina) basking on what's left of a sandbar in an estuary.

 A beautiful panorama taken by my wife.
 The first time my wife ever saw California Quail (Callipepla californica), hanging out on the road here.

 A crow (Corvus brachyrhynchos) on the beach.

 A western gull (Larus occidentalis) that got really close to my wife (I'm sure food was not involved).

 My wife and Dick Hilton prospecting for fossil marine mammals.

An articulated pinniped skeleton! We collected two pinniped skeletons over the weekend at this locality; one was disarticulated and jumbled together and took 7 hours to collect; this one was a much smaller individual preserved in a much smaller volume of rock, and took about 30 minutes. This is currently being prepared at Sierra College by Dick Hilton.

To finish off this set of photos, here's how my wife spent the day watching the waves go by and us excavating; no bitter feelings, there wasn't enough room for three at the "quarry" any way. Even though it was early October, holy hell was it hot: in the high 80's, and that white rock and sand reflected all the heat from the sun. Unlike all those poor bastard friends of mine baking in 110 degree heat in eastern Montana as I write this, I had the benefit of being able to wade out into the surf every hour or so to cool off.

Wednesday, July 25, 2012

More photos from Purisima Formation field work, 1

Since I haven't been out in the field much down here in New Zealand during the austral winter, I've decided to occasionally post photos from past field excursions. Here, I'll show some pictures from some fieldwork last fall with Dick Hilton (Sierra College) and buddy Paul Goldsmith.

Paul (right) and I (left) investigating the face (or what's left of it) of a decomposing California Sea Lion on a long walk back from the canoes.

One of the first finds of the weekend: a proximal femur of a large (dusignathine?) walrus from the Purisima Formation, just found right on the beach.

A phocoenid (true porpoise) periotic found on the beach as well, but in a cobble. This was one of about four or five phocoenid earbones found at this locality.
Paul made a friend. This guy was just sitting there near the beach.
A nice shark tooth! A specimen of Carcharodon sp. - the serrations are fine and smaller than in extant Carcharodon carcharias, and this is instead a "transitional" specimen, transitional between Cosmopolitodus/Isurus hastalis and the modern great white. This transition has been documented elsewhere in the Purisima Formation, the Capistrano Formation of Orange County, The Pisco Formation of Peru, and (potentially) the Senhata Formation of Japan. The occurrence of these teeth is chronologically similar across the Pacific basin, and can help constrain the age of a deposit to ~7-5 Ma.

Cetacean bones galore. This little bonebed yielded a bunch of other good fossils. I don't normally collect partial vertebrae like these, although it is possible that the small vertebrae represent a partial odontocete skeleton; the large bone on the right is part of a baleen whale vertebra.

What are these bones? These two were diving into the cliff, and touching when I uncovered them. I excavated these as the tide was coming in and lapping at my backpack and other gear, and after this was wrapped in tin foil, I couldn't leave the cove by walking as the water was too deep, and had to cut hand holds into the cliff. These bones ended up being a left/right pair of mandibles from the small baleen whale Herpetocetus - they are tiny, well preserved, and probably represent a very young individual based on their 'splintery' bone texture.

Paul getting ready to ferry some fossils and tools out of the cove while the tide rises.

A huge chunk of rock we collected, with a walrus skull inside. This was my first (complete) pinniped skull, and damn was I happy to find it. Actually, I take that back; at first I was pissed, because it was in a concretion the size of a refrigerator. We found this specimen in an area with nearly no fossils, and I found it on the end of our second day in the field (out of three). We were in a remote area, and we wanted to collect it - but we had no sledge hammer, and the local hardware store closed at 4. Luckily, we saw signs for a garage sale, and although we didn't find a sledge hammer, we found an old fashioned 5 lb pipe wrench, even with a hammer head on it. Dick Hilton and I spent about twenty minutes carefully sinking chisels into the nodule with the pipe wrench, and popped off the end with the skull. We then lifted the fossil in a cargo net, lowered it into the canoe, and took the specimen out by boat. The skull is now undergoing preparation at Sierra College.

A beautiful sight on our last day of fieldwork at the locality.

Tuesday, July 17, 2012

The first fossil pygmy right whale: late Miocene of Australia

The pygmy right whale (Caperea marginata) is one of the most poorly known and least understood of all modern baleen whales. The conservation status of Caperea is listed by the IUCN as data deficient. Caperea is a "small-bodied" mysticete, and is typically 7 meters in length as an adult; the pygmy right whale shares several skull features with true right whales (Balaenidea: Eubalaena spp. and Balaena) such as an arched rostrum and a mandible without a coronoid process. Historically, the mysticete fossil record has been 'plagued' with a lack of fossil pygmy right whales, and the phylogenetic position of Caperea has been contentious in molecular and morphological analyses. Skeletons of Caperea are generally rare in museums in North America, although they're relatively common here in New Zealand (and we have one sitting in one of our Ph.D. student offices).

A pygmy right whale dissection by the Fordyce lab and various other parties (this was a while before I started here at OU). Starting clockwise from lower left: Yoshi Tanaka (OU); Anton Van Helden (Te Papa); Carol Loch Silva (OU); Moyna Muller (OU); Monica Buono (CENPAT); Gabriel Aguirre (OU); Felix Marx (OU); and two gentlemen I haven't met (if anyone can identify them I'll update this caption). 

The lack of pygmy right whales in the fossil record is in stark contrast to balaenopterids and balaenids, which are some of the most common mysticetes in Pliocene strata, and are known from the early and late Miocene (respectively). Even up until a few years ago, the Eschrichtiidae - Gray Whales - were known only from a late Pleistocene skull and skeleton of the modern species from Los Angeles County. A number of latest Miocene and Pliocene finds from Japan, Italy, and California have (finally) elucidated (some of) the evolutionary history of gray whales, leaving pygmy right whales the last real 'frontier' (so to speak) in mysticete paleontology (although to be honest, the gray whale fossil record is still wanting in most respects).

The entirety of the published fossil record of neobalaenid whales, a posterior process of a petrotympanic (earbone) there on the left side, with a modern Caperea petrosal for comparison. From Fitzgerald (2012).

A new study by my colleague Erich Fitzgerald in the most recent issue of the Journal of Vertebrate Paleontology reports a partial earbone of a pygmy right whale (Neobalaenidae indeterminate) from the latest Miocene of Beaumaris in southwestern Victoria, Australia. The new find is an isolated compound posterior process of a petrotympanic (in most mysticetes, the posterior process of the petrosal and tympanic bones are fused together into one element). It shares with modern Caperea a very large, inflated, and conical posterior process, but given its incompleteness, it is not really possible to identify it past the family level (Neobalaenidae).

Phylogenetic position and stratigraphic range of neobalaenids. From Fitzgerald (2012).

Although the fossil is fragmentary and doesn't really answer any questions about character transformations in ancestors of the pygmy right whale (something which will require complete crania), it does establish for the first time that some of the weird basicranial features of Caperea have been around since at least the Miocene. That being said, more complete fossil neobalaenids were announced last year at the 2011 annual meeting of the Society of Vertebrate Paleontology by John Graf et al. of the Southern Methodist University; these include two Miocene fossil mysticete skulls from the Atlantic coast of Angola in southwestern Africa. A 'sneak peek' of the Angolan fossils popped up during Lou Jacob's presentation a year ago at the Aquatic Tetrapods meeting in San Diego, which was the first time many of the mysticete researchers in the had heard of a fossil neobalaenid, and I remember looking around and seeing other folks with their mouths dropped open (mine was). I'm skeptical of the familial assignment of these Angolan fossils, but I'll reserve judgement until they are published.

Fitzgerald, E.M.G. 2012. Possible neobalaenid from the Miocene of Australia implies a long evolutionary history for the pygmy right whale Caperea marginata (Cetacea, Mysticeti). Journal of Vertebrate Paleontology 32:976-980.

Graf, J., Jacobs, L., Polcyn, M., Mateus, O., Schulp, A. 2011. New fossil whales from Angola. Society of Vertebrate Paleontology 2011 meeting abstracts: 119A.

Sunday, July 15, 2012

Experimenting with carbon dust drawing

I've been trying my hand at scientific illustration now for the last five years or so and have practiced and learned quite a bit in the process. Most of my work involves standard graphite - and up until a few months ago, I generally only used #2 pencils; only recently have I finally branched out and started drawing with different hardness leads. I've spent some time working with other media - pen, namely. A 'lost' method of illustration I've been itching to try for a while, however, is carbon dust. I call it a 'lost' method simply because it is not widely used for illustration - however, it is a method that is barely a century old. It was invented by Max Brodel around World War 1, and was widely used among medical illustrators during the early parts of the 20th century. The carbon dust method, when executed properly, can show gradients beautifully, and highlights can be scraped into the surface of the drawing with a blade. I have been interested in carbon dust for several years, but have never gotten around to trying my hand at it because I was never quite sure how, as I could never even find carbon dust for sale. What's worse, going to art supply stores was fruitless as I never found someone even familiar with the method, much less familiar with the actual product.

The subject of my first experiment with carbon dust illustration: OU 22222, a tooth of the basilosaurid whale Zygorhiza from the Eocene Waihao Greensand of New Zealand.
A couple weeks ago I checked out the Guild Handbook of Scientific Illustration at the recommendation of my adviser, which had a chapter all about carbon dust illustration. As it turned out, you can (rarely) find carbon dust for sale, but most illustrators just grind their own dust from a carbon pencil (note: carbon, not a graphite pencil) using either a small file, a nail file, or a sandpaper block (a more typical item in the artist's toolbox). So, this realization rekindled my interest in the method. In fact, a carbon pencil can be ground on a sandpaper block, and dust can be picked up with the brush directly from the pile on the sandpaper. Carbon dust can be fairly messy, so a transparent mask must first be cut and lain over the drawing; dust can then be dry brushed on from the margins (which are usually going to be darkest), and applied in darker increments.
The result of my experiment. While stylistically identical to my other work thanks to blending, it only took 1.5 hours to draw - one half to one third the time normally spent.

I first tried drawing a sphere, which was slightly frustrating - but I found that drawing an irregular object (such as a fossil) was actually quite a bit easier, as slight imperfections in gradient are not obvious in an object that the mind knows is not a 'perfect' object like a sphere. I tried my hand at drawing an archaeocete tooth from the Eocene of New Zealand. I tried this drawing on regular drawing paper - because there was just a slight texture, it didn't paint completely evenly and there were little white spots on the 'down stroke' side of bumps on the page. This required the use of a blender to fix it, which sort of ruined the nice gradient and made the drawing stylistically identical to my other work. Still, I am pretty happy with the result, and an unexpected finding was how damn quick the process is- this drawing only took an hour and a half to do; it's about 4" x 3", and would normally have taken about four hours to finish. I was shocked when I realized I had finished a drawing so quickly. Next time I'll use a sheet of vellum, which will have the benefit of 1) not having to use a blender and 2) being able to scratch in highlights.