Thursday, 11 April 2013

Updates and Whale Reconstructions

How did a year go by so quickly?? I started a new graduate program in May 2012 and have been fairly consumed with research, classes, and studying ever since.  Despite my new work load here at the University of Kentucky, I still find time to draw every now and then.  Since it has been so very long since I last updated, I will make this a super art-packed post! I have been channeling the majority of my creative energy over the past year into a series of ancient whale drawings. I am not finished with this project, but I am happy to share what I have done thus far.

The first is a reconstruction of Dorudon atrox. Dorudon is an extinct whale ancestor in the family Basilosauridae that lived approximately 33 million years ago during the Eocene. Unlike modern cetaceans, these early whales still exhibited hind-limbs as adults. The pelvic girdle is reduced or entirely absent in modern adult whales and dolphins, however Basilosaurids were still seen with small hind-limbs. These limbs may or may not have been external, but for the purposes of my reconstruction (and most others) they are placed on the outside of the body where they may have functioned in swimming or maneuvering. I based the shape of these hind fins on the recently discovered Japanese dolphin with fully formed hind flippers.

More well-known from this group was the enormous Basilosaurus. These serpentine giants were likely ambush predators that remained motionless at the bottom of the Tethys Sea floor until some poor hapless prey animal swam within striking distance.  In contrast, Dorudon was short and sleek, more similar in size and shape to a modern dolphin. Dorudon likely used its speed and agility to chase down fish and fast-swimming mollusks. Below is a skeletal reconstruction of Dorudon and Basilosaurus side by side for size comparison. The scale bar represents 1 meter. Yeah, did I mention these things were ENORMOUS?!

The second reconstruction that I’d like to share is of my personal favorite, Kutchicetus. Kutchicetus was a small, otter-like cetacean in the family Remingtonocetidae that lived around 45 million years ago. Fossils from this extinct were discovered in India by Dr. Hans Thewissen in 2000. Unlike the Basilosaurids, the Remingtonocetids were most likely able to walk on land in addition to swimming in the water, much like an otter. While the fossils that have been uncovered for this animal are absolutely stunning (particularly the skulls!), the feet still have yet to be discovered. Instead of taking artistic liberty in reconstructing the feet, I decided to just hide them completely in the vegetation. I still need to fix a few things on this drawing, particularly the muscles on the back of the head and the substrate (there were more clams/oysters at the bottom than I have depicted here), but overall I’m fairly pleased with the composition and color scheme. 

Also, to give you a sense for the bizarre shape of this animal’s head I’ve included an older illustration I did for Dr. Hans Thewissen’s 2009 paper in Journal of Paleontology. It made the cover!

The final whale I will be sharing is Ambulocetus natans. Ambulocetus, which literally translates to ‘Walking Whale’, was also discovered by Hans Thewissen in the early 1990’s in Pakistan and is one of the earliest whale ancestors, living around 48-50 million years ago. Ambulocetus was an enormous ambush predator that inhabited both saltwater and freshwater mangrove environments. I tried to show off its crocodilian-like ambush hunting style in my reconstruction where I have depicted one particularly large animal leaping out of the water at an Eocene waterfowl.  Ambulocetus had very large hind feet and powerful hind legs that appeared to be better adapted to swimming than walking on land but, as its name implies, it was able to both walk and swim. 

Well, that’s all for now.  I will have a few more whales and many more birds and insects in the near future, so stay tuned! 

S. Bajpai and J. G. M. Thewissen. 2000. A new, diminutive Eocene whale from Kachchh (Gujarat, India) and its implications for locomotor evolution. Current Science 79(10):1478-1489

J.G.M. Thewissen, Sunil Bajpai. (2009) New Skeletal Material of Andewsiphuis and Kutchicetus, two Eocene Cetaceans from India. Journal of Paleontology. 83: 635-663

J.G.M. Thewissen, S.T. Hussain, and M. Arif (1994). "Fossil evidence for the origin of aquatic locomotion in archaeocete whales". Science 263 (5144): 210–212

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