Data from: A unique hybodontiform skeleton provides novel insights into Mesozoic chondrichthyan life

<p class="CxSpFirst"><i>Asteracanthus </i>apparently was one of the most common Mesozoic hybodontiform chondrichthyans, as remains traditionally referred to this genus have been reported almost worldwide from Middle Triassic to Late Cretaceous strata so far. <i>Asteracanthus</i> was erected by Louis Agassiz for Late Jurassic fin spines with stellate tubercles. Later, Arthur Smith Woodward synonymized <i>Strophodus</i>, originally introduced by Agassiz for distinctive crushing teeth of Triassic to Cretaceous age, with <i>Asteracanthus </i>based on associated teeth and spines from the English Middle Jurassic. This taxonomic scheme has been accepted for more than 130 years until now, although articulated material has never been found. Here, we present a unique hybodontiform skeleton from the German Late Jurassic, displaying a striking combination of characters: tuberculate dorsal fin spines reminiscent of <i>Asteracanthus</i> and multicuspid teeth that markedly differ from the crushing teeth previously referred to this genus. Using qualitative and quantitative approaches, we compared its fin spines to those that were found in association with Agassiz's <i>Strophodus</i> teeth, providing evidence that <i>Asteracanthus</i> and <i>Strophodus</i> in fact represent two valid genera distinct from all other hybodontiforms. Morphological features that distinguish fin spines of <i>Strophodus</i> from those of all other hybodontiforms include a straight anterior border and distally distributed posterior denticles. These observations led us to present an emended diagnosis for <i>Asteracanthus</i>. Dentally, <i>Asteracanthus</i> shows strong resemblance to<i> Hybodus</i>, but<i> </i>it otherwise lacks a palatobasal process on the palatoquadrate. Therefore, and in the absence of any reliable phylogenetic framework, we recommend treating <i>Asteracanthus</i> as <i>incertae</i> <i>familiae </i>until hybodontiform interrelationships are resolved.</p>