As I'm sure you know, there aren't any walruses in the Gulf of Mexico and there have not been for three million years. How can Exxon Mobil have walruses in their response plan for the Gulf of Mexico?Tragicomic as it is, the Caribbean Walrus Affair raises just the kind of stuff I like to babble about on this blog. Before this incident, I hadn't asked too many questions about walrus paleontology, or pinniped evolution in general. Now, I'm actually curious.
Were there ever any walruses in the Gulf of Mexico, or is even Markey getting it wrong?
Three million years ago, his claim for when walruses were last in the Caribbean, would put us about half-way through the Pliocene Epoch, a time of cyclic climate change in a general cooling trend, and of great waves of faunal migration.
In fact, Markey's alleged time of Caribbean Walruses almost exactly corresponds to the peak of the Great American Faunal Interchange,* a back-and-forth migration of South and North American animals sparked by the formation of the Isthmus of Panama. At first glance, this might seem like the perfect time to find walruses in the Gulf of Mexico. But unfortunately, pinnipeds are not among the fauna known to have made the transition.
(*I try to avoid using Wikipedia. But in this case, it offered the most succint summary I could find online. One day, the Citizendium -- my preferred reference site whenever possible -- will be just as thorough.)
The fossil record of pinnipeds (the suborder of Carnivora that includes seals and walruses) was, until recently, one of the most mysterious of the Cenozoic mammals. Unlike cetaceans, there was no clear fossil record with which we could reliably trace their evolution from a land-dwelling bear- or weasel-like common ancestor to the semi-aquatic forms we see today. The (then-)oldest-known fossil pinniped specimen -- Enaliarctos mealsi -- already displayed fully-formed seal-like flippers. That changed for us in 2007 with Natalia Rybczynski's discovery of Puijila darwini, the "walking seal." Both fossils date from the Miocene, E. mealsi from about 23 Ma ago, and P. darwini from about 21 Ma.
It's widely-accepted that pinnipeds first appeared in the northern Pacific coastal areas of Canada and Alaska, and radiated from there around the American continents to their present locales, possibly using the seaways between North and South America to reach their current niches. Eventually they became extinct in the north Pacific (and no, you can't pin that particular extinction on us pesky Homo sapiens), but continued to thrive in the Atlantic.
But there are lots of pinnipeds, and they are not all walruses. The oldest-radiocarbon-dated walrus fossils come from Qualicum Beach on Vancouver Island (dated at 70 Ka old), and from San Francisco Harbor (dated at 27.2 +/-0.95 Ka). In the Atlantic -- which is where BP's mythical Caribbean Walrus would reside -- their fossil record is rather more robust... but doesn't stretch any farther south than Nova Scotia [Source].
So as far as modern paleontology can tell, there have never been walruses in the Caribbean. I'm not sure where Rep. Markey is getting his paleo-data, but considering the difference between his mistake and BP's, I think I can let him slide on this one.
But while there may not have been any walruses in the Caribbean or the Gulf, there used to seals. The Caribbean monk seal -- last seen in 1952 -- was driven to extinction by human hunting, the first seal species to suffer this fate. Sadly, if current trends continue, they won't be the last. The IUCN lists five seal species on their infamous Red List, and the creatures have long deservedly been iconic symbols in both the animal rights and environmentalist movements.
Chuckles and learning aside, we have a lot of work to do to save these precious creatures.