Friday, January 27, 2012

New artwork: reconstruction of a remingtonocetid whale

Some time last fall I sat down and sketched out a drawing of Remingtonocetus, after Bajpai et al. (2011) was published. This new study described a new, nearly complete (and beautifully preserved) skull of Remingtonocetus harudiensis from India. The remingtonocetids are possible one of the only monophyletic groups of archaeocetes, and all appear to be relatively small-bodied, with ridiculously big heads and long rostra, very tiny and dorsally placed orbits, heterodont dentitions, and long tails. Perhaps the best way to imagine a remingtonocetid is to picture an otter with the (furry) head of a gharial.

The skull of Remingtonocetus harudiensis, from Bajpai et al. 2011.

The holotype skeleton of Kutchicetus minimus, from Bajpai and Thewissen (2000).

I had inadvertently sketched the head too small on the body, so when I completed the drawing over Christmas break with my wife's family in Montana, I ended up with a critter with a head that is way too small (although it looks like a less absurd beast, to be quite honest).
The original, unaltered drawing.

To fix this, I did some editing in photoshop after I had scanned the image - mostly by enlarging it's head about 20% or so. I also decided to experiment with texturing, and ended up with something that fairly convincingly looks like fur; I'm still experimenting with drawing fur in pencil, and as you can see between these two - the photoshopped version looks quite a bit better. Texturing can be pretty difficult on a small drawing - the original is only about 6" long from nose to tail. I was also able to make the wet fur on 'his' nose a little 'spikier'.

The modified version of the artwork. Overall, I'm quite satisfied with this piece, and am rather surprised that I was able to portray an archaeocete cetacean as "cute" - archaeocetes in general are pretty nasty, scary looking beasts, like Ambulocetus, Basilosaurus, Georgiacetus, and Dorudon.

The skull of Andrewsiphius, from Thewissen and Bajpai (2009).

There are a number of different remingtonocetids, including Remingtonocetus, Andrewsiphius, Kutchicetus, Attockicetus, and Dalanistes. Only Andrewsiphius and Remingtonocetus are known from good, well preserved crania. Bajpai et al. (2011) suggested that, based on the strange skull anatomy of Remingtonocetus, that remingtonocetids were ambush predators that were heavily reliant upon hearing rather than sight. The muscle attachment area is very large, and coupled with the very narrow jaws - suggests that remingtonocetids had a weak, but very fast bite, well suited for ambushing and catching small fish. Additionally, because Remingtonocetus was aquatic, the extremely long snout was probably not an adaptation for improved olfaction; Bajpai et al. (2011) hypothesize that as Remingtonocetus was one of the first marine cetaceans, this may have been an adaptation towards retention of freshwater during respiration.

Next up - continuation of the southern California research trip, Kolponomos, my Purisima vertebrate assemblage paper, desmatophocid taxonomy, etc.

Further reading:

A different kind of Whale, at Laelaps

Bajpai, S., and J.G.M. Thewissen. 2000. A new, dimunitive Eocene whale from Kachchh (Gujarat, India) and its implications for locomotor evolution of cetaceans. Current Science, 79(10):1478-1482.

Thewissen, J., & Bajpai, S. (2009). New Skeletal Material of Andrewsiphius and Kutchicetus, Two Eocene Cetaceans from India. Journal of Paleontology, 83 (5), 635-663.

Bajpai, S., Thewissen, J.G.M., and R.W. Conley. 2011. Cranial anatomy of Middle Eocene Remingtonocetus (Cetacea, Mammalia) from Kutch, India. Journal of Paleontology 85(4):703-718.

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