What is that thing?

The Tully Monster has been an enigma for half a century. Now it's been reconstructed on the basis of analysis of 1200 specimens.

tullymonsterrecon

That thing is weird. It's been extinct since the Carboniferous, though, so we're not going to be catching any nowadays, unfortunately. Note the eyes on stalks; the tubby body; the long 'snout' terminating in a toothy jawed mouth. People have been grappling with its taxonomic identity for decades, and it's been labeled as various kinds of worms, or a mollusc, or an odd relic of some Cambrian phylum.

The latest comparisons, though, have convincingly identified on common trace in the fossil as the remnant of a notochord -- that makes it a chordate, and everything else begins to fall into place. It's got a 3 lobed chordate brain, and gill openings, and rays of cartilage internally, and segmental myomeres. Not only is it a chordate, it seems to be a relative of hagfish and lampreys…their weird funny-looking cousin. And when you're funny-looking compared to a hagfish, you're really out there.

Now though, I want to know what they were doing while they were swimming about here in the Midwest 300 million years ago. What were they eating with that strange proboscis?

Tullimonstrum, FMNH PE 40113, oblique lateral view (also Extended Data Fig. 2a): eyebar, Eyb; myomeres, My; gill pouches, GP; caudal fin, CF; notochord, No; otic lobe, OtL and optic lobe, OpL of brain; and dorsal fin, DF. d, Line drawing: black, teeth; brown, lingual organ; light grey, eyebar; dark green, gut and oesophagus; red, notochord; light green, brain; orange, tectal cartilages; pink, naris; purple, gill pouches; yellow, arcualia; dark blue, myosepta; blue with black stripes, fins with fin rays. Scale bar, 10 mm. Tullimonstrum, FMNH PE 40113, oblique lateral view (also Extended Data Fig. 2a): eyebar, Eyb; myomeres, My; gill pouches, GP; caudal fin, CF; notochord, No; otic lobe, OtL and optic lobe, OpL of brain; and dorsal fin, DF. d, Line drawing: black, teeth; brown, lingual organ; light grey, eyebar; dark green, gut and oesophagus; red, notochord; light green, brain; orange, tectal cartilages; pink, naris; purple, gill pouches; yellow, arcualia; dark blue, myosepta; blue with black stripes, fins with fin rays. Scale bar, 10 mm.

VE McCoy,EE Saupe,JC Lamsdell,LG Tarhan,S McMahon, S Lidgard,PMayer,CD Whalen,C Soriano,L Finney,S Vogt,EG Clark,RP Anderson,H Petermann,ER Locatelli, DEG Briggs (2016) The ‘Tully monster’ is a vertebrate. Nature doi:10.1038/nature16992.

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As an Entomologist with huge interests in invertebrates, I was long fascinated by the Tully Monster and speculated on what it might be. My personal favorite theory was that it was some weird mollusc. I haven't decided if it's disappointing or extremely cool that it's been figured out that it was vertebrate, and a lamprey relative at that.

By John Peloquin (not verified) on 16 Mar 2016 #permalink

I think you've just found the secret weapon for use in debating creationists and intelligent design advocates.

"Oh yeah? Look at THIS!"

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It seems to me that the long snout with jaws at the end could be adapted for plucking small prey out of hazardous surroundings. For example prey that nest amidst the poisonous tentacles or appendages of something that has limited ability to detect an intruder at any distance. Or prey that hide in holes, where the narrow snout can get in and grab them.

In a weird way it looks like a multicellular lacrymaria olor. I can almost imagine it using that little trunk the same way!

By Will Holz (not verified) on 17 Mar 2016 #permalink