Sep
19
2008

Science Buzz Creature Spotlight: The Crocowhale

The Ambulocetus: Not looking very fearsome at the moment, but it's thinking horrible, horrible thoughts.
The Ambulocetus: Not looking very fearsome at the moment, but it's thinking horrible, horrible thoughts.Courtesy ArthurWeasley
It’s Friday, y’all, and you know what that means!

No, not falling asleep at a booth in Applebee’s (should have gone to TGIF, right?)!

No, not a methadone suppository (not from me, anyway)!

And, no, not matching butterfly tattoos (that’s a Saturday thing)!

What’s left? Why a Science Buzz creature feature, of course! Sure, Friday has never been Creature Spotlight day before, sure, and, yes, it’s unlikely that I’ll remember to do it next Friday… But, hey, we’re Buzzketeers, right? We live in the now.

And so, with a small current science introduction, the creature of the week:

The crocowhale* (also known as ambulocetus, or “walking whale”).

If you’re keeping up on your cetacean evolution paleontology, you might have noticed this story recently. The ancestors of whales, paleontologists are quite certain, were land animals. Finding the evolutionary steps of their return to the water has been a challenge, however.

The distant ancestors of whales were carnivorous ungulates (ungulates are hoofed animals), that probably looked a little like dogs (with hooves). At some point these creatures began adapting to live and hunt in and around the water, eventually evolving into fully aquatic species.

Living vertebrates that swim employ a variety of propulsion methods. Several swimming styles seem to develop in sequence as a group of animals becomes more fully adapted to living in the water: swimming with four legs, paddling with just the back legs, undulation of the hips, undulation of the tale, and finally oscillation of the tail. The sequence of whale ancestor fossils seemed to follow this pattern (with modern whales having lost their hind legs to propel themselves with just their tails), except that for a long time it appeared that the step of swimming by hip undulation.

Recent fossil discoveries, however, show a whale ancestor that appeared to have a long fluke-less tail (it didn’t have big tail fins, like a modern whale), along with long hind legs and large, webbed feet. The skeleton seems to indicate that this creature would have propelled itself by undulating its hips, using its webbed hind feet as hydrofoils. And so, la de da, we have an important step in whale evolution in the bag. But, for the creature spotlight, we’re going back a couple branches in the cetacean family tree.

Before the group had evolved to the point of the hip wiggler above (called georgiacetus, by the way), there was the ambulocetus. Ambulocetus was a creature that probably still spent some of its time on land. It was about 10 feet long, and moved around on short, powerful legs. With its eyes and nostrils located on top of its long head, it probably looked something like a furry crocodile. Indeed, paleontologists think that ambulocetus probably acted very much like a crocodile, and filled a similar ecological niche.

Ambulocetus could have waited for large prey almost entirely submerged in shallow water, with only its eyes and nostrils breaking the surface. When something worthwhile came down to the water’s edge, it could have launched its body out of the water with its particularly powerful hind legs, ambushing its prey. The ambulocetus would have then dragged its struggling meal back into the water, and waited for it to drown. Yes! Crocowhale!

Here’s a cool illustration of ambulocetus in action.

* “Crocowhale” is a brand new term, and while I’m all for you using it in everyday life, don’t put it in any biology papers or anything. Yet.

Your Comments, Thoughts, Questions, Ideas

JGordon's picture
JGordon says:

Hmm. All that stuff about whale evolution—MDR posted on it days ago. Check it out.

He didn't mention the crocowhale (and how could he?), but, still, I give my post 1 star.

posted on Fri, 09/19/2008 - 2:11pm
ARTiFactor's picture
ARTiFactor says:

I did a post a couple of years ago titled Solving the mystery of whales missing legs (click on red words to see it) if anyone is interested.

posted on Sat, 09/20/2008 - 12:13pm
Anonymous's picture
Anonymous says:

This is pretty neat!!

posted on Sat, 09/20/2008 - 12:15pm

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