juvenarium

plural juvenaria · plural juvenariums

1. A shell or portion thereof of a foraminifer in the youngest stage of shell-building.

   The earlier figure may be considered to represent this form, for the latter figure is an atypical specimen with multiple juvenaria.

   1959, Walter Leroy Moore, Pennsylvanian foraminifera from the Big Saline formation of the Llano uplift of Texas

   2 more examples

   Later on, the above three genera evolved until various levels of the Eocene in America with unchanged equatorial chamber build-up, but with the microspheric juvenariums becoming more and more simple.

   1987, Geologica Hungarica: Series palaeontologica - Volume 51, page 74

   Test large, subspherical, biumbilicate, inflated, early whorls closely coiled, forming a fusiform juvenarium, later whorls rapidly enlarging in height but coiling axis enlarging more slowly so that adult test becomes globular and strongly umbilicate, final whorl of reduced height as in Pseudoschwagerinal wall of tectum and keriotheca, chomata prominent in the fusiform juvenarium, very faint in later wholrls.

   2015, Alfred R. Loeblich Jr., Helen Tappan, Foraminiferal Genera and Their Classification, →ISBN, page 284