Juraphyllitidae is a family of

Lower Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is a un ...

ammonites Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttl ...

from Europe, North Africa, and Asia characterized by narrow, evolutely coiled shells, usually with coarse ventral ribbing on the body chamber. The first lateral saddles in the suture are diphyllic, with two terminal branches, others exposed sutural saddles are diphyllic or triphyllic, those covered by successive whorls being monophyllic. A few genera are more involute, with successive whorls partially embracing the flanks of the previous. All are compressed and a few lack ribbing. The Juraphyllitidae are probably derived from the Late Triassic

Discophyllitidae Discophyllitidae are discoidal, generally evolute Phylloceratina from the Upper Triassic, derived from the Ussuritidae, in which the principal saddles of the suture have bifurcated or trifurcated endings, described as being di- or triphyllic. D ...

and independent from the

Phylloceratidae Phylloceratidae is the predominant family of the Phylloceratina with some 15 or more genera found in rocks ranging from the Lower Jurassic to the Upper Cretaceous. Members of the Phylloceratidae are characterized by smooth, involute shells with v ...

. They apparently left no descendants. Eight genera are included: :'' Juraphyllites'' :'' Tragophylloceras'' :'' Dasyceras'' :'' Schistophylloceras'' :'' Paradasyceras'' :'' Meneghiniceras'' :'' Harpophylloceras'' :'' Galaticeras'' Distinctions are based on variations in overall form including nature of ribbing, ventral surface, and degree of involuteness.

References

{{Taxonbar, from=Q6314885 Ammonitida families Phylloceratina Early Jurassic first appearances Early Jurassic extinctions