On Oct. 14 of this year, as construction crews were clearing ground to expand the Ziegler Reservoir near Snowmass Village to increase snowmaking capacity, bulldozer operator Jesse Steele uncovered the bones of a juvenile female mammoth. What happened next was a minor miracle: he recognized them as fossils, and didn’t doze them.

Instead, he and others got on the horn (as it were) with the Denver Museum of Nature and Science. An emergency paleonotological response team (how many times does that happen?) was dispatched. Just over a month later, stymied, for now, by snow and frozen soil, the museum took a step back, a big breath, and has realized they have stumbled onto the find of a lifetime.

Spake Museum Curator Kirk Johnson to the Denver Post:

“We know almost nothing about what the Rockies were like during the ice age. We have our first clear window into it,” museum curator Kirk Johnson said. “It is one of the most amazing finds in North America.”

It was he who has publicly suggested the town should be redubbed Snowmastodon Village, for here is what they have found, according to the Post:

Museum workers — 67 individuals — recovered more than 500 bones representing eight to 10 American mastodons, four Columbian mammoths, four ice-age bison, two deer, Colorado’s first-ever Jefferson’s ground sloth and several smaller animal species, and hundreds of pounds of plant material. . . Scientists have in house 15 tusks of mammoths and mastodons — one still bone white — plus two tusk tips and 14 bags of tusk fragment.

For those of us who also care about things without fur, the Post was gracious enough to report that the team has also found:

* One tiger salamander

* Distinctly chewed wood that provides evidence of Ice Age beavers

* Insects, including iridescent beetles

* Snails and microscopic crustaceans called ostracods

* Large quantities of well-preserved wood, seeds, cones, and leaves of white spruce, sub-alpine fir, sedges, seeds, and other plants.

Truly, this is The Age of Mammals, the companion mural to the Age of Reptiles at the Yale Peabody Museum, come alive. Age? The final word isn’t in yet, but it’s looking like somewhere between 40,000 and 130,000 years old. To give you a sense of the timing, the last interglacial began about 130,000 years ago, and the last ice age began about 100,000 years ago, ending just 10,000 years ago. You can read more about the discoveries in the Post here and here.

 

I have to say I do want to know more about the Ice Age beavers. I’m imagining they had some pretty sweet ice age digs — you know, lodge all tricked out with mammoth-fur lined walls and satellite TV. Like these guys.

 

In any case, on Saturday, the Museum held a Mastodon and Mammoth Madness Day at the Museum to show off a handful of their finds for one day only before everything disappears for a few years to be preserved. Yours truly made sure to attend (I do it all for you, dear readers) so I could be there for those of you who couldn’t. When I arrived I found swarms of children and a variety of non-Snowmass fossils blocking the way to the main event. No matter, I parted the seas to find the proper table. There, volunteers were assiduously misting the unprepared bones with squirt botttles.

Here was the first bone I looked at — a mastodon tusk. Note the blue stains.

A volunteer informed me those are actually a blue mineral formed from the biological ooze in the bone. The name is escaping me, but I think it was a woman’s name starting with a V + ite (Vanessite?)

Notice the tip. It’s not broken. Here’s a closer look.

Though it’s a little hard to see in this photo (go look at the photo at the very beginning of this post too), the end is worn smooth, from use in life. Just like the wear and tear on your molars. Speaking of which . . .

Here is the jawbone of a Columbian mammoth with one of its worn-down and extremely characteristic molars. They look like some sort of funky scrubbing pad, if you ask me. I LOVE the pattern. But even cooler than that is what lurks in that little shadow next to the tooth. See inside? It’s *a new* molar, just waiting to erupt. And unlike the existing molar, its crown is perfectly pointy and unworn.

You might be able to see it a little bit better here:

Mammoth teeth are very distinct from mastodon teeth. For comparison, here’s a mastodon molar, which looks much more like our own:

So by now you may be wondering, “Just how big were mastodons and mammoths compared to us and each other?” Well, I’m glad you asked — the museum had handy dandy banners made up, and I inserted myself into the picture as your human scale bar. I am quite a short human, though — only 5’2″ (just over 1.5 m). So bear that in mind. : )

Here’s a mastodon, which as you’ll see, is a little smaller than an elephant:

And here is the Columbian Mammoth — which was much bigger!

Columbian mammoth — or oliphaunt?

The museum also had bits of other fun stuff they found in the peat from which they’ve been excavating the bones, including lots of bits of grass and grass seeds:

Those are tens-of-thousands-of-year old grass seeds and blades, folks. And they look like they just fell yesterday! Would be fun to see if you can get any of them to germinate. They also had a very tiny piece of peat with an irridescent blue beetle butt, but the light was too bad and my camera too poor to capture it well. The beetle was so well preserved they could identify it to family as a Buprestid.

Alas, they didn’t have the sloth bone on display, but they did have a giant sloth skeleton from another site displayed:

Pretty scary looking, eh? And yet, according to the volunteers, those scary claws were used for digging up ant and termite mounds. Here’s some more info and a nice reconstruction.

Finally, I happened to notice this inconspicuously laid on a table nearby. Real woolly mammoth hair!!

I’m sure it came from a frozen mammoth somewhere. Though they found Columbian mammoths — not woolly mammoths — at this site, it was still so cool to see. The box had like six different “NEVER OPEN THIS” stickers, but to me, it was so wonderful that, in theory, I could pet the fur of a mammal long extinct from the Earth. The bones at Snowmass seem to have come from a swamp or lake, so the odds of finding fur are slim. But you never know . . . there’s always next season. And I can’t wait to find out what’s still buried out there, high up and lonesome at 8,874 feet.

Is it just me or do these guys' snouts have a bit of a star-nosed mole feel? Creative Commons wondoroo

A bit of interesting news this week: the humble and much-reviled hagfish (“disgusting” seems to be its most common moniker) was knocked off its podium at the evolutionary junction between vertebrates and invertebrates.

Perhaps we should begin at the beginning: what is a hagfish? Glad you asked: it’s a serpentine, sea-dwelling, knot-tying, slime making scavenger that lacks vertebrae (a bony spinal column that protects the dorsal nerve cord), compound eyes, or true teeth. It does have a rudimentary skull, but it lacks compound eyes, having instead only simple eyespots. And about that slime: there’s a lot of it, and it’s really noxious. Grabbing a hagfish by the tail will result in a veritable deluge of the sticky, gill-clogging stuff, which may be why hagfish’s only predators are birds and mammals, not fish, and why after sliming themselves, the hagfish has to tie itself in a knot that it works down its body to wipe its own slime off. Some theorize that even the *hagfish* can’t breath through the stuff if they leave it on too long.

Wikipedia drily notes:

An adult hagfish can secrete enough slime to turn a 20 litre (5 gallon) bucket of water into slime in a matter of minutes.

‘Atsa lotta slime.

In any case, for a long time hagfish were apprently classified with the jawless lampreys on the big ‘ol tree of life. They were considered to be the earliest representatives of the vertebrates, from the time before jaws had evolved.

For those of you who might have difficult remembering from high school biology or who have never had the pleasure of seeing one up close, here is a view into the mouth of a lamprey:

A sarlacc? No, a lamprey. Creative Commons edans

Is it just me or does this somewhat horrifying angle resemble this? Lampreys are famous for their parasitic lifestyle: they latch onto the side of fish with their horrible, horrible rows of teeth and suck until they can suck no more. (Possible bionerd bumper sticker idea: Lampreys Suck)

In any case, DNA studies eventually seemed to show that the hagfish actually were more primitive than lampreys, providing the “missing link” between the most complex invertebrates and the most primitive vertebrates — the lampreys. Now new studies of snippets of RNA called microRNA seem to show they are actually as they first seemed: closely related to the much more easy-for-scientists-to-work-with lampreys*.

In all the time scientists were working on hagfish, they were only able to find *three* embryos in the entire 20th century. And if I had to choose between the horrible rows of teeth or the suffocating slime? Teeth. Fo’ sho. Although I have to say the hagfish are cuter. Though admittedly, we’re talking about a pretty low bar here.

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* For the biologists in the room: microRNAs date me; I cannot recall learning about them in the late 1990s when I was in college, but they are big, apparently, now: very short segments of RNA that latch onto messenger RNAs in the short, untranslated section at their tail ends and turn them off. They are also strongly conserved among species, making them, like ribosomal RNA, great for looking at large-scale evolutionary relationships.

The Gothic Cathedral of the Triceratops family: Kosmoceratops. Creative Commons Sampson SD, Loewen MA, Farke AA, Roberts EM, Forster CA, et al. "New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism". PLoS ONE 5 (9): e12292. DOI:10.1371/journal.pone.0012292.

Note: Clarifications/corrections added below. See comments section.

Ya know, some headlines write themselves. This past month an article in PLoS One announced the discovery of this new, vaguely-late-’80s-esque addition to the ceratopsian oeuvre (let’s face it: dude’s got bangs). What a startling and beautiful structure atop this dinosaur’s head! — like a shark-tooth necklace, or a very ambitious sea star. But the real news here seems to be that dinosaurs were no different than modern animals: they were subject to the whims of sexual selection as well as natural selection. And oh, what a harsh mistress sexual selection can be to the poor males of the species.

You see, what females really desire is an honest indicator of fitness. Males will try to fake their way to reproductive success (aka gettin’ some) in any way they can. It’s in their genes’ best interest, since they can generally impregnate as many females as they like with little cost. Females, on the other hand generally incur great cost in reproducing. Eggs and pPregnancies and raising offspring (*see Ben’s astutue comment below) are expensive energetically, while sperm and a father’s contribution to child-rearing are usually cheap. If you’re a female member of a few unlucky species, you could be stuck looking after your young for days, even months(!) before they leave the nest. Bummer.

So if you’re female, you want to be choosy. Not just any old male will do. You want a male who has demonstrated his fitness in a way that can’t be faked or cheated. This selection pressure, incurred by females, has led to the evolution of energetically expensive (and often ridiculous but strikingly beautiful) or cerebrally-demanding male traits. Witness peacock tails, bower bird bowers, sage grouse struts, mockingbird songs, and Shakespearean sonnets. Intelligence or fluorescent feathers can’t be faked; one must genuinely be bright to sing snippets of 30 songs or construct an elaborate love nest. One must genuinely be healthy and strong to grow the avian equivalent of a day-glo Persian Rug and nonetheless escape the clutches of hungry predators. Thus females can make informed decisions about whom to let sire their offspring*.

Well, no matter how long ago they lived, dinosaurs were still subject to the same cruel female whims, it seems. Enter Kosmoceratops, the elaborately frilled dinosaur. For once, biologists gave the bony crown atop ceratopsian dinosaurs (the frill) a beautiful, apt name. But what’s the deal with all those horns? Well, scientists suspect (according to the article in Time) that the horns were probably useless in taking on predators and may have even made it harder for the animals to move around. They suggest they were either used to intimidate other males of the species, or attract females. To me, they have sexual selection (i.e. useless, borderline dangerous, but unspeakably sexy to females**) written all over them.

Strangely, it seems these ornately-horned dinosaurs evolved *before* the simpler (and perhaps more elegant) frills of Triceratops, Nedoceratops, and a few other species, so Kosmoceratops or one of its close relatives was thus in fact the *ancestor* of Triceratops, not the other way around. Here is an example of evolution operating in the direction of complex to simple, or baroque –> neoclassical, if you will. So take note: evolution doesn’t always mean simple –> complex. All that matters is that the trait is changing in a way that leads to more offspring. Perhaps the gnarly frills proved too unwieldy, difficult to clean and maintain, or less tasteful to females than they at first seemed. Maybe the ladies decided that scarlet chest crests were the new sexy of the early 70’s million B.C.

To explore how the ceratopsian dinosaurs fit into the rest of their thundering kin, see here, and click on “Ornithischia”.

And just a quick note — I did hear about the discovery of the possible culprits in Honeybee Colony Collapse Disorder, and you will be hearing my thoughts on that (and description of the perpetrators) here soon. : )

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*Oddly, and for reasons I don’t entirely understand (except that the predator-free islands of the tropical birds of paradise (from which many of my examples are drawn) has allowed sexual selection to run amok), much research into the world of sexual selection has been done in birds. In one experiment involving birds whose females evidently found extremely long tail feathers erotic beyond belief, sadistic biologists clipped or gave tail feather extensions to variously naturally-endowed males. They found the birds’ reproductive success depended only on the length of those tail feathers, whether honestly come by or not: artificially-lengthened males suddenly found themselves getting much luckier than their better naturally-endowed but snipped brethren. Presumably, in nature, the birds can’t cheat the system by ordering a Swedish Tail Feather Enlarger.

** there are any number of human analogs that suggest themselves here

Image courtesy of NOAA Okeanos Explorer Program, INDEX-SATAL 2010.

One of the most intriguing images caught by the Okeanos Explorer was this portrait of a ghost shark, or chimaera*. Sporting a mask-like face that seems to combine the most haunting characteristics of the spook and demon bunny from Scream and Donnie Darko, this animal is one that would surely strike fear in any heart were one to encounter it mano-a-fisho at 4,500 feet. At the same time, there is a sculptural beauty in its features that is hard to define and rarely encountered elsewhere in the vertebrates, or backboned animals. And those eyes  — those ghostly eyes . . . not to mention the spiked retractable sexual organ on their foreheads.

What makes the real-life chimaera extraordinary is its place in the tree of jawed fishes: it may be the most anciently formed lineage around today. Chimaeras split from sharks sometime in the Paleozoic, the several hundred million year stretch preceding the Mesozoic, or age of dinosaurs. It happened sometime before the Permo-Triassic extinction 250 million years ago (the greatest Earth has ever seen) that ended the Paleozoic, and the Cambrian explosion, “modern” life’s great diversificiation, which took place some 550 million years ago.

Specifically, it happened during the Devonian (ca. 420-360 million years ago), a time of great experimentation, a time when early armor-plated fishes like now-extinct placoderms roved the seas. It was just at this time that three major groups of jawed fish — the placoderms, cartilaginous fishes (chimaeras are in here) and ancestors of ray-finned fish (most everything else) — evolved from jawless fish that might have resembled lampreys or hagfish. The resulting group, the gnathostomes (lit. jawed mouths), represented a major milestone in vertebrate evolution. Jaws are great for crunching and munching. That is, for grasping relatively large prey so it can’t get away while you’re trying to eat it, and for magimixing your prey once teeth evolve on the jaw. The previous, less-enticing system can be summarized (not entirely, but relatively closely) by its section title in my college biology text: “Sucking Mud: The Rise of the Vertebrates”.

As cartilaginous fishes, chimeras share several features with the sharks and rays. All cartilaginous fishes, or Chondrichthyans (sharks, rays, and chimaeras), possess a cartilaginous skeleton**, though it seems they once possessed bone. For one, their sister group, the extinct placoderms, were armed to the teeth in bone (As an aside, the armoring of fishes seems to have taken the opposite path of the evolution of European armor: fish seem to have started with large bony plates and evolved toward the mail-like coats of scales seen today***. Contrast this with sharks, who are literally armed with teeth, since their placoid scales and all vertebrate teeth evolved from the same ancestral structure). And second, cartilaginous fishes (and all jawed fishes) seem to have evolved, like the placoderms, from bony jawless fish.

Chimaeras are the most primitive (i.e., split off from the rest of the groups earliest) of the cartilaginous fishes. They are crunchers of hard food, possessing, instead of rows of bristling, disposable razor blades like sharks, permanent bony plates which they use for crushing mollusk shells like nutcrackers. The vast majority are found in deep, dark water far from coasts.

Most notably, males of these species don’t possess a penis, but they do possess an arsenal of other interesting sexual organs. Like sharks, near their genital opening they possess a pair of “claspers”, which they use to grip the female in the pertinent location, and which have grooves for funneling sperm. Some chimaeras take this one step further by deploying what can only be described as a medieval-looking cephaloclasper that expands and retracts from the tops of their heads (view all these delightful accoutrements here). To my knowledge (which is very small), no one has actually ever seen this thing in use, so speculations on its actual purpose and function are just that. It is a good thing men don’t have such a thing, since they’ve already got enough problems with the ones they’ve got getting stuck in zippers, hotel rooms that rent by the hour, weekend “hikes on the Appalachian trail”, etc. If they had spiked, retractable sexual organs on their foreheads. . . well, God help us all.

Adding to the thrill of what must certainly be some of the most interesting sex in the vertebrates is the added difficulty that each one of these babies carries a spine in front of their dorsal fin loaded with a venom sac at its base. Which means the joke must go: How do chimaeras mate? Answer: Very. Carefully.

The equally fascinating product of all this maneuvering is something that is also known from the world of sharks: beautiful, leathery egg cases (see longitudinal view, left), also called mermaid’s purses. They are deposited on the seafloor where they harden and darken as the young chimaeras grow within. Some sharks have developed vivipary, or live birth, like humans, but that does not seem to have happened yet for chimaeras, and I can’t blame them. I know I’d rather lay a nice, rounded egg case and kick back with a margarita to watch on the blessed day. Stupid natural selection.

Here’s a nice tree showing the vicinity of the chimaeras at the jawed fishes junction . . .

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*Those who have studied Greek mythology will recall that the classical chimaera was a fire-breathing lioness with a snake for a tail and a goat’s head improbably sprouting from its back. Today the term is used in biology for individuals with cells that originally came from two different zygotes, or fertilized eggs. How or why the ghost shark acquired this name I have not been able to discover.

** but they do have calcified stiffenings of their backbones that function like vertebrae

*** Alive without breath,
As cold as death;
Never thirsty, ever drinking,
All in mail never clinking.

Additional sources:

The Variety of Life (Tudge)

Life (Purves, Orians, and Heller, 4th ed.)

These snakes seem to have evolved to capitalize on the veritable all-you-can-eat buffet of ant and termite larvae in the soils of many desserts and steppes. Though they’re thin as earthworms and only a few inches long, that’s more than enough, evidently, to tackle the teeming hordes of these nests. It’s as if someone released the sandworms of Dune on the planet of Aliens, but they all took a swig out of the “Drink Me” bottle. And someone made the sandworms cute:

Another organism seemingly designed by the Japanese! As you can see, blind snakes are not truly blind. They have two eye spots they can use to get an idea of where the big yellow hot thing is, roughly speaking.

And can these guys ever burrow. Leptotyphlops humilis, the western blind snake that inhabits my little corner of the world, has been found cruising around as deep as 66 feet underground. These organisms have several interesting strategies for gettin’ ‘er done, including a thick skull (! — this thing has a skull?) selected for burrowing and a spined tail they can use to gain leverage in their ant and termite colony-pillaging operations.  When they find their prey, the suck out the hemolymphy, creamy centers and leave the exoskeletons or shells behind.

Scientists recently discovered and reported in Biology Letters that a particular subgroup — the blind snakes — somehow made it to from Africa to South America tens of millions of years after the splitting of the two continents and *without* using any frequent flier miles. Wha?

To figure this out, the scientists used the sequences of five genes to compare the differences and thus gauge relatedness between blind and thread snakes. They they used a molecular clock (an occasionally dodgy timepiece that gauges time based on number of accumulated mutations in coding genes) to estimate the time since different blind snake species shared a last common ancestor.

Some diversification was due (unsurprisingly) to continental drift: the ancestors of the threadsnakes were marooned on West Gondwana and the blindsnakes on East Gondwana and diversified accordingly. There seem to have been further splits in the blind snake lineage when India separated from Madagascar.

But their data yielded the further surprising result that the blindsnakes must have dispersed across oceans on at least three occasions: 28 million years ago from southeast Asia to Australia, 33 million years ago from South America to the West Indies, and 63 million years ago — incredibly — across the Atlantic Ocean, some 40 million years after Africa began to split from South America (ca. 100 million years ago). OK, now getting from Southeast Asia to Australia doesn’t seem so bad, and maybe one can see how they could manage the South America to Caribbean trip. But Africa to South America? Now it’s true that 63 mya sea levels were lower then and the Africa and South America much closer together. But the scientists still estimate the trip by blindsnake would still have taken as much as six months. Six months!

K. So it’s a blind snake. It has no legs, wings, fins, or reasonably functional eyes. How the heck did it accomplish what it takes humans with, at the very least, a row boat, a GPS device, half a million calories freeze-dried food, and several months of blog-documented travel to accomplish? Well, if you’re small, don’t really need to eat much or row, have packed along your food supply, and you have millions of years for just one blind snake ark to finally reach the promised land, odds are it will happen.

Scientists refer to the actual vehicles of dispersal as “rafts”. You might think of them more like floating terrariums, but what exactly were they? Were they pieces of soil and moss that happened to float? A rotting, termite-infested but still mighty tree? A Princess Cruise Ship? The ever popular African Swallow/coconut combo? Who knows. One way or another, the S.S. Scolecophidea made the Atlantic crossing.

Take home message from scientists: Even species that are total landlubbers (even landdwellers) can fire up a sea chanty when the right cruise opportunity presents itself.

Vidal, N., Marin, J., Morini, M., Donnellan, S., Branch, W., Thomas, R., Vences, M., Wynn, A., Cruaud, C., & Blair Hedges, S. (2010). Blindsnake evolutionary tree reveals long history on Gondwana Biology Letters DOI: 10.1098/rsbl.2010.0220