Alienacanthus: a Devonian sea robin, not a placoderm per se

Still experiencing tech difficulties here
so no pix again today.

As a work-around: to see images click here, which will take you to ReptileEvolution.com.

Alienacanthus malkowskii
(Jobbins et al 2024, Late Devonian, 365myA) was originally considered a placoderm with a very long lower jaw and illustrated without much of an upper jaw. In the LRT Alienacanthus nests with sea robins like Prionotus and Satyrichthys, both of which also have an armored skull, sloping profile and a short cranium. Apparently the likely long rostrum (based on comparative anatomy), perhaps longer than the long mandible, was lost during collection or taphonomy.

Distant ancestors of sea robins in the LRT include placoderms.

References
Jobbins M, Rücklin M, Sánchez, Villagra MR, Lelièvre H, Grogan E, Szrek P, Klug C 2024. Extreme lower jaw elongation in a placoderm reflects high disparity and modularity in early vertebrate evolution. R. Soc. Open Sci. 11: 231747.
https://doi.org/10.1098/rsos.231747

wiki/Alienacanthus