Friday, September 22, 2017

Protosphyraena: Like a Swordfish Made Babies With a Chainsaw

We're back from SVP 2017 in Calgary, which was an awesome opportunity to debut our prototype Protosphyraena (Proto Proto) skeletal reconstruction. I've been involved with this project for 13 years now, very heavily for the past 4 with my various research projects with Drs. Jeff Liston, Kenshu Shimada, Bruce Schumacher and Matt Friedman. We've published a bunch of papers and talks recently, and there's even more on deck. If you're in Tahiti next week, stop by and hear my talk!
Image Copyright Mike Everhart
Loomis' reconstruction attempt

Protosphyraena was a tough nut to crack. The first bits were discovered in the late 1700s in the English chalk and first figured by Gideon Mantell in 1822. It got its name later in the mid 19th Century by Joseph Leidy meaning "early barracuda" due to the flat knife blade shaped teeth. Unfortunately this is what happens when you only have sparse material to work with. Protosphyraena is known now to have a basically worldwide distribution however since the animal has replaced its skeletal bone with cartilage wherever possible, more than isolated bits are extremely difficult to come by. In the Bone Wars of the late 1800s, Cope and Marsh's teams discovered many partial specimens in the Niobrara Chalk of Western Kansas, consisting mostly of isolated pectoral fins and skull bits.
Pectoral of P. perniciosa showing saw-tooth edge

The skull was amazing, with a long rostrum and forward-directed massive protruding teeth. The fins showed some variation, however the ones attributed to Protosphyraena perniciosa reached nearly a meter in length ad were adorned with saw-like serrated front edges. A tail fin was discovered near the turn of the last century and then one the first reconstructions was attempted by Loomis.
Cast and original parts at beginning, apple for scale

Not too shabby based on what they knew. Since the body had such little bone, it was highly unlikely that one would be found, yet the Niobrara as usual was full of surprises. In 2003 Mike Triebold found a partial Protosphyraena skull eroding out of the rocks in western Kansas. The specimen was already missing its rostrum, but a bit of pectoral fin was also visible. He continued excavation and noticed articulated evenly spaced spines, and followed them. They were ribs, hemals and neurals, ans they led to an articulated tail. This was the first "complete" Protosphyraena discovered.
Dig site pic, the specimen is already uncovered and pedestalled

This specimen ended up becoming the "Rosetta Stone" for our reconstruction attempt. Though it was a small example, it gave us tons of information about the body proportions. it kept on giving though, showing the streamer-like pelvic fins and large lobe-shaped "go faster" caudal peduncles.
The "go faster" caudal peduncles

We prepared out several specimens of large Protosphyraena in order to have a decent starting point for the reconstruction. One good skull specimen was partially disarticulated, we scanned the gill basket of a second smaller one and reproduced it out at the proper size on our 3D printing rigs. Our pectoral fin donor specimen was famously covered here as the victim of a poaching attempt in 2011. The original bones were molded and we made multiple copies of the parts so we could cut them up into individual elements. They were later remolded with most of the distortion taken out.
The kid seems bored

Jaws attached

Complete skull exterior

After that, the process was pretty easy! We decided to ignore how bizarre the critter was and just accept that's how these parts fit together, seeing where the reconstruction took us. It tuned out to be stranger than we ever imagined, and a lot bigger too, measuring over 2 meters in length (and flipperspan). We showed it off in Canada and it seemed to be a big hit! Enjoy the photos of the finished mount below.
I'm useful as a scalebar sometimes

Down the hatch!

Front view

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