Axelrodichthys araripensis Maisey, 1986 revisited

Axelrodichtys is a genus of fossil coelacanth of the family Mawsoniidae with a wide spatial and temporal range, spanning from the Aptian/Albian of Brazil to the Campanian of France. In light of new discoveries in recent years a renewed interest in Axelrodichthys has emerged. Here we offer new insights on the type species – A. araripensis – based on a complete new description of all its morphological characters and a comparative study of several other Mawsoniidae. A relatively large sample composed of 113 specimens of A. araripensis and associated Mawsoniidae species was observed. Among the newly observed features are the broad aspect of premaxillae supporting the anterior opening of the rostral organ; a unique pattern of skull roof ornamentation; the basioccipital; a passage of nerves in the prootic; the passage for the superior ophthalmic nerve; the anocleithrum; and ossified zygal plates. Observation of two juvenile specimens in different growth stages allowed for the inference of negative allometric growth in the epicaudal lobe. Morphological comparisons pointed out that M. lavocati is more closely associated with the Axelrodichthys than with Mawsonia, therefore we included it in the Axelrodichthys genus as A. lavocati.