Alienacanthus'holotype, MZ VIII Vp-45, was referred to A. malkowskii in 1957 by Kulczycki, (1957). It consists of what were originally interpreted as "fragments of large osseous spines".[1] However two epitypes described by Jobbins et al., (2024) that preserve more material shows that what Kulczycki, (1957) interpreted as "spines" are in fact fragmentary inferognathals.[2] The epitypes, PIMUZ A/I 5239 and MCD 201, both comprise "a nearly complete articulated skull with all gnathal elements." and "left side of partially preserved skull with all gnathal elements." respectively.[2] The combination of a short upper jaw and elongated lower jaw is a striking case of convergent evolution with halfbeaks.[2]Alienacanthus was likely piscivorous, with jaws bearing sharp, posteriorly recurved teeth on both its upper and lower jaws, suggesting a grasping and trapping live prey.
Etymology
The generic name, Alienacanthus (IPA:[ˌalienaˈkantʰus]), derives from the Latin 'aliena' which means alien, and 'canthus' which means spine, referring to what Kulczycki, (1957) thought were spines. The specific name, malkowskii (IPA:[ˌmawˈkɔvskiaɪ]), is named after Prof. St. Malkowski, the former Director of the Muzeum Ziemi in Warsaw; Poland.[1]
Classification
Originally, Kulczycki, (1957) described Alienacanthus as a putative placoderm, noting that the traits the holotype possessed did not belong in either Selachii or Acanthodii.[1] Jobbins et al., (2024) ran a parsimony analysis utilising a character matrix based on 98 characters for 28 taxa. The analysis resulted in Alienacanthus being recovered in Selenosteidae in a polytomy with Amazichthys, and a polytomic clade comprising Melanosteus, Enseosteus, Walterosteus, and Draconichthys.[2] Their results are shown below:
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