Inspecting Mazon Creek plant fossils.

Spartobranchus tenuis.

Spartobranchus tenuis was an endobenthic (burrowing) enteropneust (or acorn worm) from the Burgess Shale. It is the earliest known enteropneust worm, predating the previous example by 200 Ma. Although common in the Walcott quarry, with a few thousand specimens known, it was nicknamed "Ottoia" tenuis until scientifically described in March 2013.

Unlike living enteropneusts, Spartobranchus made fibrous tubes in the sediment. It looked much like its modern counterparts, except for the fact that it had a posterior bulb that could probably expand to anchor the worm in its burrow so that it would not be extracted by predators such as Opabinia.

Spartobranchus was a hemicordate, and the third hemicordate from the Burgess Shale (one is Chaunograptus, a benthic graptolite, the other was Oesia, a vermiform animal that appears to belong somewhere in hemicordata). Spartobranchus was a deposit feeder and may have played a role similar to modern earthworms.

Although previously thought to have evolved from the colonial pterobranch hemicordates, fossils of Spartobranchus tell us that enteropneusts were present in the Cambrian Period and common in at least one place, the Burgess Shale community. The fact that S. tenuis built tubes suggests pterobranchs evolved from enteropneusts that built similar tubes.


Here are some cool images of the fossils:
http://www.nature.com/nature/journal/v495/n7442/images/nature12017-f2.2.jpg
and
http://www.nature.com/nature/journal/v495/n7442/images/nature12017-f1.2.jpg

Note from The Mom: New blog post?! Art didn't dictate this to me, but wrote it out himself. 

References:

Tubicolous enteropneusts from the Cambrian period

Figure 2: Spartobranchus tenuis (Walcott, 1911) individuals associated with tubular structures, from the Burgess Shale.

Burgess Shale worm provides crucial missing link

Finished For Now.

I haven't added to the blog in a long time and I've decided that it's finished for now. I think I did the best I could to write about the subject and it was really fun. I hope people will continue to read it even though I'm no longer making posts. Thank you for reading my blog and thank you to all the people who helped me.

I'm currently studying mycology, astronomy, minerals, marine biology, and immunology. I'll still sometimes put interesting things on twitter.

Art

On Sabbatical.

A huge thank you to everybody following Life Before the Dinosaurs and wondering why Art hasn't posted in a while. You guys are the best!

Art is in the middle of a particularly busy school year (third grade is insane) and the blog had to be back-burnered. He's on sabbatical! Art is still studying and studying and studying--it's his favorite thing to do. I'm confident he will be back with a new post soon. Thanks again to everybody!

The Mom