Leymeriellidae is a family of Lower Cretaceous

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 cuttlefish) ...

comprising rather small forms distinguished from

Hoplitidae The Hoplitidae is a family of Cretaceous ammonites that lived during the middle of the period from the late Aptian to the Cenomanian. They are part of the superfamily Hoplitoidea. Members of the Hoplitidae are typically evolute, with inner whor ...

by their flattened and grooved ribs and virtual absence of umbilical tubercles. The family is derived from the

Desmoceratidae Desmoceratidae is a family belonging to the ammonite superfamily Desmoceratoidea. with and (1996), ''Mollusca 4 Revised , Cretaceous Ammonoidea'', vol. 4, in ''Treatise on Invertebrate Paleontology'', Part L (Roger L. Kaesler et el. eds.), ...

. '' Leymeriella schrammeni anterior'' has evolved from '' Desmoceras keilhacki keilhacki''.BERT, D. Les ammonites du niveau Paquier (Albien basal, Crétacé inférieur) du Sud-Est de la France. Fossiles, 2012, 12: 4-25.

Taxonomic position

Leymeriellidae are currently regarded is belonging to the

Acanthoceratoidea Acanthoceratoidea, formerly Acanthocerataceae, is a superfamily of Upper Cretaceous ammonoid cephalopods belonging to the order Ammonitida, and comprising some 10 or so families.W.J Arkell ''et al''., Mesozoic Ammonoidea; Treatise on Invertebrate ...

according to W. J. Kennedy ''et al'' (1980). The previous placement was in the

Hoplitoidea Hoplitoidea, formerly Hoplitaceae, is a superfamily of mostly Upper Cretaceous ammonites comprising families united by a similar suture pattern with multiple similar elements that tend to decrease in size going toward the umbi ...

according to W.J. Arkell ''et al'' (1957) in the '' Treatise on Invertebrate Paleontology, Part L''.

Genera

Leymeriellidae includes the following genera: *'' Leymeriella'' Jacob 1907. Shell evolute, venter flat to sulcate. Ribs single, wide spaced, grooved in outer part. ''Lower

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± 0.9 M ...

to Middle

'' *'' Proleymeriella'' Breistroffer 1947. Shell moderately evolute, whorl section oval with constrictions present throughout. Ribs single, strong, form chevrons on a narrowly rounded to acute venter. ''Lower Albian'' *'' Epileymeriella'' Breistroffer 1947. Differs from ''Leymeriella'' in that the ribs branch from weak umbilical bullae. ''Lower Albian''

References

*W.J. Kennedy ''et al''. 1980. Albian and Cenomanian ammonites from the island of Bornholm (Denmark). Bull. geol. Soc. Denmark 29:203-244
Leymeriellidae
Paleobiology Database. {{Taxonbar, from=Q16984520 Cretaceous ammonites Acanthoceratoidea Ammonitida families