Fossil lamprey larvae overturn textbook assumptions on vertebrate origins

[Gwangi]

Fossil lamprey larvae overturn textbook assumptions on vertebrate origins
https://www.eurekalert.org/pub_releases/2021-03/uotw-fll031021.php?fbclid=IwAR1J2JpjhgZe9fpp1BU2hckSjIw3Pkij58ZnnPPOBhNvwo291ZtbIPIUds0#.YEnNTOznqrE.facebook

The paper, not open access.
Non-ammocoete larvae of Palaeozoic stem lampreys
https://www.nature.com/articles/s41586-021-03305-9?fbclid=IwAR1ILZzTKNesgQ2PRTVCUKH6qCpg7YQqahUfzeWW9GywAl2axofDbnuSu7g

[Halichoeres]

I love stories like this, that show how hazardous it is to infer the ancestral condition of a species-rich lineage by looking at a species-poor lineage and assuming it's primitive in all respects.

If anyone would like a pdf, pm me your email address and I'll send it your way.

[Newt]

Ooh, nice!


Speaking of lampreys and how weird they are, I vaguely recall talk 20 years or so ago that there might be a larviform population of Ichthyomyzon in the Mississippi Embayment of West Tennessee that never fully metamorphosed. Not sure what's happened with that. If it's more than a rumor, it's an interesting example of a neomorphic life phase becoming the only life phase.


Also, the feeding/non-feeding species pairs of freshwater lampreys are pretty cool. Repetitive parallel evolution at its finest! It's kind of like the successive anole ecomorph radiations in the Caribbean islands, but more consistent.

[Halichoeres]

I'm not familiar with that particular Ichthyomyzon population, but that general part of North America is where I'd expect to find something funky like that. What a treasure trove of endemism your backyard is.

[Newt]

Yeah man. Which reminds me - it's getting to be spawning season! I wish I had time to go swim with all of our pretty little darters and minnows in their breeding colors. Lousy gainful employment and home ownership, always ruining my fun. 


If you ever get the chance to come to Tennessee in April or May, it's definitely worthwhile to seek out a mid-sized rocky creek where the Nocomis chubs make their huge pebble tumulus nests (just like lampreys do, one rock at a time) which are then absolutely swarmed with hundreds of nest-commensal dace and shiners resplendent in their nuptial glory. An old snorkeling friend of mine called it "liquid sunshine".

[Halichoeres]

I've seen something very similar with chubs and dace in Minnesota, at a fish farm where they set up a donut-shaped artificial stream to breed bait fish. I didn't snorkel, so I didn't get the full glory, but it was still very cool to watch.