Long in the Hoof

Lower molar of a new Cretaceous mammal from India
from Prasad et. al 2007.

Behold: Kharmerungulatum vanvaleni - Van Valen’s “ungulate” from the Kharmer River!

Our picture of Mesozoic mammals has been paroxysmal. Fossils like
Repenomamus and Volaticotherium have hacked away at the stereotype of Mesozoic mammals as uniformly pitiful bits of dino-bait. Meanwhile molecular investigations of mammal phylogeny retrodict a Cretaceous diversification of most extant mammalian groups. The isolated molar shown above, presented in last year’s Science (Prasad et. al, 9 November 2007), adds a yet another tiny, curious wrinkle to the story.

The first thing to note is the absurd tininess of the tooth. It’s about 2.5 millimeters long, “half the size of an ant” as LiveScience notes. Or, .002 London bus equivalents. Next is the shape of the tooth: broad, and relatively sturdy with rounded cusps. This suggests that the animal was an herbivore. “We consider Kharmerungulatum to represent an early stage in the evolution of ungulates.”

Fair enough!

REF:

Prasad et al. 2007 - A Cretaceous Hoofed Mammal from India — Science 318 5852: 937 

Death Throes pt. 2: Opisthomonotony.

In the incursive preamble we spiroambulated about the corpses of mummified dinosaurs, pickled pelicans, time and a piss-covered pseudo-esker of rock, rock salt and dust. So, what does all of this have to do with experimental taphonomy?

Afrotheres of the World Unite!

The recent description of a new species of sengi, Rynchocyon udzungwensis, inspired me to finally complete a project I’ve been talking about for years. Behold: the official Afrotheria logo–soon to be seen on a bumper-sticker or t-shirt near you!

(Note: while the new sengi is freaking huge, tipping the scales at 700g, the animals in the logo are, um, not to scale).

“Gondwanaism and Afrothereists” is the name of a chapter in my book Paleontology After Modernism which will almost certainly never be written.

I ultimately decided not to include the extinct Afrothere lineages Desmostylians and Embrithopods, despite the fact that they are some of my favorite mammals, because I was afraid it would look too crowded, plus my lab-mates were starting to ask questions.

Anyone who can name all seven taxa pictured will win a free t-shirt, once I get around to printing them…

Props to Seth Newsome for the inspiration.

Now I guess I had better get to designing logos for Xenarthra, Laurasiatheria and Euarchontoglires.

Smells like Shrew Spirit

Star-nosed Mole (Condylura cristata) “sniffing” underwater

from Catania 2006

The kind of thing to drive any formerly self-respecting paleontologist nuts: underwater olfaction in mammals. Smell is an important sense for mammals, no surprise to anyone who has stepped into a Sephora outlet recently. Though we are generally far more conscious of sight and sound, we’re still led around by the nose far more than we would guess…especially when it comes to eating and mating.

And other mammals, especially those who have stuck to more respectable mammalian lifestyles (i.e. grubbing around for worms and bugs at night), put humans to shame in the olfaction department. Still, the announcement that some specialized “insectivorans” (or soricomorphs if you’re T.C. like that) are able to smell underwater came as a surprise - to me at least.

As seen in the photo above, this amazing feat is accomplished by expiring a small bubble of air then re-inspiring it. This allows these air-breathing mammals to safely search for odors underwater as they search for prey. Notably, many other aquatic mammals rely exclusively on other senses especially hearing and touch; whales have apparently little or no sense of smell judging from their brains.

A detailed analysis of the tactile and olfactory abilities of the American Water Shrew (Sorex palustris) in PNAS, expands upon the initial report of underwater smelling by shrews and moles. Like the previous Nature paper there are awesome photos and slow-mo videos documenting this amazing behavior, highly recommended.

The elaborate experiments by Catania and co. showed that S. palustris uses a combination of tactile (via whiskers) and olfactory clues to evaluate potential prey items. One video shows a shrew puzzled by an artificial cricket which apparently “feels” right but “smells” wrong. They also used experiments to rule out echolocation or electroreception - strategies employed by other mammals that forage underwater.

As for the paleontological lament: it took a serendipitous flash of insight plus the availability of high speed cameras and infrared lighting to bring this interesting behavior to light. One has to wonder how many strange behaviors among fossil taxa, peculiar and mundane, have yet to and may never be guessed at.

Interestingly, aquatic olfaction has been suggested in plesiosaurs based upon skeletal evidence, but I suspect we’ll be waiting awhile for the slow-mo vid.

Solstice is Over Man!

So, I won’t waste my time wishing y’all a happy holiday. I converted to animism on I-5 just south of Lodi, beneath a wheeling gyre of White Pelicans. Mahayana blows
dude. Sorry.

Those pelicans then shall be our collective mascot this holy season, their holding pattern a gleaming metaphor for our soul. Which is to say, don’t be surprised if things are pretty quiet around here for the rest of the week.

In the mean time:

- Jennifer Rae Atkins pulled of the astonishing feat of drawing twenty-four mammals in twenty-four hours and in the process raised $800 for Defenders of Wildlife. With the help of several gallons of vanilla DP, she even managed to slam my “diabolical” curve-ball request out of the park. Go check out her awesome work!

- Entomologist, photographer and one-time Davisite, Alex Wild has launched an awesome ant-blog Myrmecos. Wild’s photography is truly amazing and has often made me want to chuck my camera off a cliff. Fortunately, since the camera doesn’t belong to me, there aren’t many cliffs in Davis. His blog may well drive me to lob my laptop into the Interstate though.

- Mechanical insect art by Mike Libby! Crazy…

- Tai’s tales of auspicious animal encounters reveals the patent grayness of my animistic sphere. But I saw an octopus! and cranes! and like, multiple scorpions some of which I held so cut me some slack.

- I was desperately hoping to take up the Schmitz et al. paper in the inaugural issue of Nature Geoscience and the broader issue of the Ordovician radiation and the growing impulse to invoke bolides as a causal agent for all dramatic biotic events… But, well we’re gonna have to wait for that.

So, here’s your homework - “What are the benefits and dangers of applying neoecology notions like disturbance ecology or island biogeography to evolutionary or extinction events in the fossil record?” Write a three to five page review of the issue including at least six primary references and one figure, due January 15th 2008.

okay, we’ll leave it at that, if I haven’t had cause or opportunity to apologize to you in person this year, I’m sorry.  There’s always next year!

Er…How about Mink-tailed Muntjac with Marfan’s?

Okay, I’m going on record in defense of our favorite AP word-smith, science writer Seth Borenstein.

In a nice blogpost on Indohyus, [the sexiest new raoellid on the block] Brian takes Borenstein to task for some awkward animalian analogizing:

writer Seth Borenstein can’t seem to figure out just what Indohyus is. His confusion is apparent from the first line of the article;

It sounds like a stretch, but a new study suggests that the missing evolutionary link between whales and land animals is an odd raccoon-sized animal that looks like a long-tailed deer without antlers. Or an overgrown long-legged rat.

Borenstein scrabbles¹ to lump Indohyus in with some modern animals in a feeble attempt to get people to understand the fossil find, but I can’t help but wonder if such a comparison does more harm than good.

As I noted in a comment on Brian’s blog however, Borenstein cribbed his ungainly comparison from the lead author on the Indohyus paper Hans Thewissen, at least in part:

“The earliest whales didn’t look like whales at all,” Thewissen said. “It looked like a cross between a pig and a dog.” They lost their legs and ability to walk on land about 40 million years ago, he said.

And the Indohyus? “A tiny little deer maybe the size of a raccoon and no antlers,” Thewissen said. He said it most resembles the current African mousedeer, which has a rat-like nose and “when danger approaches, it jumps in the water and hides.”

Sure, maybe it’s a misleading oversimplification to cast the cetacean ancestry debate as a war between the “racoon-deer campus” and the “hippo campus².” Sure, trying to shoehorn every strange animal into this or that familiar category or combo of categories is a dubious (though longstanding and universal) habit. But, as long as we’re not ‘calling whale evolution into question’ hey, I’m pretty happy.

Sometimes, words just fail. Good thing we have Carl Buell. Check out Buell’s awesome reconstruction on Laelaps.

¹ - Note the awesome verbing of the word “scrabble”.
² - sorry.

Wave Bye-Bye to the Polymath…

Well, calling Charles Willson Peale a polymath may be rather generous. Then again, if I had run a failed saddle shop, painted some bossy white dudes, and created the first American Natural History Museum, I think I’d probably feel pretty worthy of the title. Anyway, when was the last time you went to a glass harmonica concert or whatever? [well, knowing microecos readers, it was probably last weekend]

At any rate, before we tossed his geriatric remains from the bell jar, I figured it was worth giving the bloke a proper post. Exhumation of the Mastadon [sic] (1806) (pictured above) remains probably the best American painting to date, though some of Richard Estes’ stuff comes close. That is, of course, ol’ Pealey himself in the jacket and slacks. Much, much more Peale info here.

microecos is a rotting peaty wreck.