Yanliaomyzon, the first known Jurassic lamprey

[Halichoeres]

Lampreys have obviously been around for hundreds of millions of years, but fewer than a dozen species are known from the fossil record because they don't have any bones or teeth, and their proteinaceous bodies are rarely preserved. Until a couple weeks ago, there were no lampreys described between the Carboniferous and the Cretaceous. Enter Yanliaomyzon, a new genus from the Jurassic of China. The authors describe two species from the same locality, with the largest being over half a meter long, relatively large for a lamprey. These are from the same series of formations as famous tetrapods like Anchiornis, Yi, Jeholopterus, and Volaticotherium.

The fossils and accompanying reconstructions. Really long dorsal fins on these guys.


The description (Wu et al. 2023) is open access: https://www.nature.com/articles/s41467-023-42251-0

[Saarlooswolfhound]

That is an amazing discovery but also a little terrifying, what weird animals!

[Newt]

Very interesting! I haven't read the paper yet, but my first thought on those fins is they look like adaptations for swimming in a lentic environment, as opposed to the more high-energy environments most lampreys inhabit today.

I wonder if the two sympatric species are a species pair representing a form with a parasitic adult and one with a non-feeding adult, as occurs in modern lampreys.

*EDIT* They're both predatory, with fish bones preserved in the gut. I really should read the paper before engaging in speculation.

[Faelrin]

So the large one is about the size of the extant sea lamprey, if not a little bigger? Any other extant lampreys (or prehistoric) that compare? Absolutely wonderful they found not one, but two species, and well preserved. Kind of an underappreciated group of animals, in part to many being parasitic in nature, and the horrifying jawless mouthparts.

[Halichoeres]

@Faelrin large sea lampreys can be bigger than these specimens for sure, well over a meter long. But most modern freshwater lampreys are much smaller.

@Newt the fins remind me of a bowfin or some kinds of kmifefish, along the lines of what you're suggesting. I get the impression that sea lampreys are extremely lazy swimmers, while these guys seem like they would be a bit more active.