Bakker blogs: Bulldozer worms and the end of peace on the ocean floor

Life first evolved about 3.5 billion years ago, at the beginning of the Precambrian Eras. At first, life was made up of simple microbes (bacteria) that could survive horrible conditions, including acid oceans and no oxygen in the air or water.

For 2.7 billion years, the sea bottom remained (mostly) peaceful, quiet and flat. Microbes built wide mats that sealed the mud surface, stabilizing the sediment.  Advanced microbes like blue-green algae began pumping oxygen into the atmosphere and ocean. The microbes had few enemies — no big, energetic animals disturbed the bottom. Day after day, week after week, year after year, bits of sediment kept falling down through the ocean water. The clay and silt continued to make layer after layer of sediment, and the ecosystem was stubbornly two-dimensional — all life lived on the surface or the bottom.  The subsurface was empty.

Then, around 700 million years ago, the Vendian Period began. A few life forms like Charnia and its kin got up to a half a foot tall, acquiring the shape of bloated feather plumes. Still, no one was churning up the mud or otherwise disturbing the microbial mats.

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Life in the Pre-Cambrian still was lovely, idyllic and BORING!

Today’s oceans teem with life forms that burrow through the bottom mud and live in cleverly constructed holes. Thousands of creatures, large and small, plow through the sediment looking for food. Plowers and burrowers include snails and bristle worms, long-necked clams and sea-cucumbers, plus a bewildering variety of groups without common names. The Precambrian world was totally devoid of all this action.

Finally and suddenly 540 million years ago, the Precambrian peace was broken. The Vendian Period ended when the microbial mats were attacked and ripped apart. Holes were excavated down into the mud. Bottom sediment was churned up. The long reign of the soft, quiet, two-dimensional world at last was terminated.

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The Cambrian Explosion had begun.

From this moment on, the rules of life were changed, and the ecosystem went into 3D. Dozens of new species evolved to take advantage of living deep in the mud. Other species hunted the species in the mud. Still more species swam above the surface looking for prey hiding below. Trilobites appeared and flourished. Fishy-things evolved.

Who destroyed the Precambrian mats? Who released the potential of evolution? Where do we send the thank-you note?

The fossil burrows are clues. At the end of the Vendian and the beginning of the Cambrian Period, U-shaped burrows appear all over the globe wherever shallow seas existed. Something was diving down through the mats and coming back up, again and again. This was the burrower who was destroying the ancient system of mats.

There are suspects alive today that make U-shaped burrows quite like the ones that ripped apart the Vendian bottom. Usually these critters are no bigger than a small pickle. Under the microscope, these burrowers look as fierce as the man-eating worms in the movie Tremors — the beasts have stout, muscular bodies with a face that carries a scary array of hooks and barbs. When they bump into prey, the hooks snag on their victim and the whole face inverts, dragging the meal into the throat.

800px-Priapulus_caudatusThe cactus worm, close-up.

You can find these mini-monsters in the mud in most oceans. Technically, they are called “Priapulida,” but they have many nick-names. Our favorite is “cactus worms.”  Because they have no bones or hard shells, cactus worms have almost zero chance of being fossilized unless there are very special conditions. The cactus worm would have to be buried instantly by an underwater landslide that killed the worm and sealed it under a thick blanket of sediment,  keeping out any scavengers.

For the first century of paleontological explorations, up until 1909, no one could find such an avalanche bed. Then Dr. Charles Doolittle Walcott, Cambrian expert from the Smithsonian Institution, hiked up into the Canadian Rockies near Burgess Peak in British Columbia.  He was looking for Cambrian trilobites, his specialty. He found what he was looking for flattened in dark slabs of clay, but there were other species, too — animals with no shell or hard parts at all.

Most exciting were the worms. Dozens of kinds of worms. Worms that ate microbes. Worms that ate trilobites. Worms that ate other worms (“Lutheran Worms”). Walcott had found the Holy Grail of Cambrian history.

But was there evidence of cactus worms? Yes!

Now we knew for certain that cactus worms had thrived in the transition from Vendian to Cambrian. We could be sure that these worms had overturned the Precambrian peace and begun the Cambrian Explosion.

They may be ugly, but remember these little creatures; they were the dynamos that restructured the oceanic world.

Weird (Careers in) Science: Meet Keith Strasser — scientific sculptor extraordinaire

Here at Beyond Bones, we’re launching a new segment to spotlight the sort of science careers you might not think to think of. Most people know what a curator does, but what about careers in cast-making, the transport of artifacts or scientifically accurate sculpture?

We’ll introduce you to at least one of those professionals today. Meet Keith Strasser, New York-based scientific sculptor and creator of the dazzling Dimetrodon replica that’s soon to be on display in our new Hall of Paleontology.

dimetrodon replica
Pretty impressive, no?

How does one become a designer of dinosaur sculptures?

Strasser started his career building and repairing musical instruments, and soon concluded that wood is not the most forgiving of mediums; if you make a mistake, you’re pretty much toast.

Eager to try out a more flexible material, Strasser tried his hand sculpting in clay and submitted the result to a contest in Boston. His first go — a figure of a dragon — won first place, and Strasser hasn’t looked back.

Borrowing medical anatomy books from his chiropractor brother, Strasser set to work learning how muscles and bones interact. Before long, he was creating scientific sculptures for a company that had seen his work at the contest. One of the very first maquettes Strasser made was for a Dimetrodon — the same maquette was used for the Dimetrodon on display in the new Hall of Paleontology!

“That guy’s been my meal ticket for 15, 20 years!” Strasser says.

He’s since worked for a number of museums, theme parks and other commissioners on scientific sculptures of all sizes, from a 30-foot Parasaurolophus to 3-foot lady bugs.

Strasser begins with a wire form and then fleshes it out with clay, although the materials he uses depend heavily on the proposed size of the specimen he’s creating. Its outer layer can be cast in any number of materials; some are cast in resin, others in plastic. “There are many ways to top a mountain,” Strasser explains.

He says one of the best things about his job is the artistic license he gets to take when it comes to imagining the skin and coloring of his creatures. Take a look at the Dimetrodon replica in our paleontology hall. How do you envision him?

She has a gift: 7-year-old Hannah Aaronson lends a rare Anomalocaris to HMNS’ new Hall of Paleontology

Anomalocaris. This shrimp-like creature, which measured about 6 and a half feet long, was the biggest predator of the Cambrian Explosion — around 530 million years ago.

It was a funky-looking thing, with two funny feeding appendages at its front and undulating lobes down its sides. It was a swift swimmer, and feasted on trilobites much the same way we eat crawfish today — breaking them open and sucking out their insides.

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Our top-of-the-line Anomalocaris replica, courtesy of a generous young donor.

To suss out the teensy trilobites, Anomalocaris used its super sharp vision. It had 30,000 lenses in each eye — compare that to the dragonfly’s 28,000!

When something is hundreds of millions of years old, it’s easy to understand why a complete specimen might be hard to come by. Although the Museum does have an original arm segment of a 500 million-year-old Anomalocaris, we wanted a high-end replica so patrons could get an idea of what this creature was really like.

Japan-based Griffon Enterprises had just such a model. The problem? It wouldn’t be on sale for many months after our new Hall of Paleontology opened to the public.

Enter miss Hannah Aaronson. Hannah won one of the company’s original prototypes in an auction, and decided to lend her spiffy prehistoric model to the Museum.

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Hannah and her mom at the installation of her Anomalocaris at HMNS’ new Hall of Paleontology.

Hannah’s generous gift — on loan for one year — helps to complete the evolutionary story of the trilobite. Anomalocaris had been a mysterious creature to scientists for some time, and many now speculate that it may have contributed to trilobites evolving the ability to roll up for protection.

Once the model becomes available for purchase, the museum will get its own Anomalocaris and return our current model to its rightful owner, who promises to visit it while it’s on loan to HMNS.

Of course, you should visit, too! The new Hall of Paleontology opens Friday to members and June 2 to the general public.

The votes have been tallied: Your new mascot is called…

Tiny the Tyrannosaurus rex!

You all sure appreciate a sense of irony — Tiny won our naming contest with 104 votes over Tex’s 85. The remaining nominated names trailed behind, with Huey coming in at 19 votes, Sam with 10 and Amigo with eight.

We’ve gotta say, we were pulling for Tiny all along. Just look at him; it’s perfectly paradoxical:

T-Rex trying to crack a geode!
Tiny the T.Rex is having trouble cracking this geode. He should come to HMNS’ geode-cracking station!

The winning name was first nominated by Katy Yeager Huggins, who won four passes for a guided tour of the new Hall of Paleontology. Congratulations, Katy!

Tell us: What do you think of Tiny the T. rex?