PHYLLOCERAS (Jurásico superior, Kimmeridgiense)

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Phylloceras (Oxfordian to Late Jurassic, approximately 155 million years old). Sierra de Cazorla (Jaén)\nClass Cephalopods, Subclass Ammonoidea, Order Ammonitida, Family Phylloceratidae\nPhylloceratids were involute, relatively flat ammonites with unornamented shells, and in some cases, growth lines can be observed. The suture lines (intersection between the external shell and the septa) are especially sinuous, which has been interpreted as a reinforcement of the casing against implosion when reaching deep zones. Possibly this group of ammonites performed migrations related to day-night cycles in the water column like many modern cephalopods. Phylloceratids can be found from marine platform rocks to oceanic environments.\nThis specimen is an internal mold and does not preserve the original shell.\nCEACTierra-UJA. Institute of Giennean Studies. Projects 2018