‘Size dimorphism, in which the heteromorphs are slightly larger than the tecnomorphs, can be recognized in late instars.’
‘Ancyloceratina, which contains all other Mesozoic heteromorphs, evolved from Perisphictidae during the Tithonian.’
‘Most heteromorphs form a U-shaped chamber, whereas many normally coiled ammonites inflate or enlarge the terminal body chamber and constrict the aperture.’
‘In the stages A - 3 to AI heteromorphs can be distinguished from tecnomorphs by slightly broader velum in the anteroventral region.’
‘The presence of occasional preadult heteromorphs was mentioned also by Schallreuter, Jones and Meidla.’
‘Most heteromorph ammonites have a hooked terminal body chamber.’
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