Two successive assemblages of vertebrate microremains have been
found at Grozon (Jura,
northeastern France). Palynological analysis confirms a Norian age for
the first one and a Rhaetian
age for the second. A new species of neoselachian shark, Grozonodon candaui, is erected from isolated
teeth of Norian age, based on their enameloid ultrastructure. Distinctive
parallel-fibred enameloid is
recognized among teeth previously assigned to Hybodus minor, which
therefore represents another
early neoselachian shark. These structural characteristics confirm the
close relationship of hybodont
and neoselachian sharks.