The gonorynchiform fish Dastilbe from the Lower Cretaceous of Brazil

We examine the preservation, autecology and morphological variation for sev eral characters of the Cretaceous gonorynchiform fish Dastilbe from the Low er Cretaceous of Brazil and Africa. More than 83 specimens were examined. W e test species validity using characters of the caudal endoskeleton and mer istic counts of fin-rays vs length. Evidence provided by fossilized soft ti ssues and slabs containing large individuals 'freeze framed' in the process of swallowing smaller prey meals, show that Dastilbe was predatory, at lea st as adults, as well as cannibalistic. Dastilbe was probably an anadromous fish tolerant of hypersalinity and in Araripe was subjected to frequent ma ss mortality events. Observations of the otic region indicate that the lage nar statolith is consistently larger than the saccular statolith, hence rev ealing a primitive actinopterygian condition. For the first time, a lagenar statolith from Dastilbe has been cleaved to expose putative annuli-like ri dges. Our results clearly show that there is a wide degree of morphological plasticity of the endoskeleton coupled with wide meristic variation, and a s such, overall length, fin-ray count and even absence or presence of cauda l diastema are not suitable criteria for species recognition in Dastilbe. N ew specimens from the Crate Formation (Aptian) and statistical tests sugges t rejection of all species of Dastilbe erected subsequent to Jordan (1910). All Brazilian Specimens of Lower Cretaceous Dastilbe can be assigned to th e single species D. crandalli Jordan. The African D. batai Gayet is also pl aced within D. crandalli.