The "T.b" Letter Stage roughly equates to the Late Eocene (c. 39 to 34 mybp)
The images shown here are reduced to about 1/5 their original resolution and highly compressed as JPG files. Original images available on request, as TIF files from 120 to 400 MB in size
- Late Eocene Limestone (352 KB). From the Pasir area of SE Kalimatan
- Late Eocene Limestone (448 KB). From Papua New Guinea, with abundant Vacuolispira and a few Tansinhokella specimens.
- Late Eocene Limestone (444 KB). From the top of the Nanggulan section Central Java
- Late Eocene Limestone (428 KB). Also from the top of the Nanggulan section Central Java. Ths small view contains Biplansispira, N. gerthi as well as an advanced Heterostegina (Vlerkina) almost approaching the morphology of the descendant Tansinhokella. Black dot is 100 microns.
- base Late Eocene Limestone (516 KB). This is from the rarely visted Cimuncang site in West Java, first reported by Koolhoven (1933) - report on this site. This small limestone lens does not appear to have the "Assilina" reported by Koolhoven but does have a small, flat, involute Operculina that only slightly resembles the modern concept of "Assilina" or Planocamerinoides. This site has both granulate, moderately dimorphic Nummulites that would normally be considered diagnostic of the T.a Letter Stage, but with advanced species of Pellatispira. This limestone is baked due to mineralisation in the area, - hence the low contrast in this thin section. As a consequence mudstones here are poorly fossiliferous, but a few have yielded fairly good Late Eocene, P15 faunas.
- Late Eocene Limestone, Christmas Island (544 KB). Christmas Island is now only some 380 kms south of the coast of Java, but in Eocene times would have been over two thousand kilometres further south, and an isolate off the Australian Plate. Faunas here would therefore be expected to be similar to Australian Lacazinella fauna, rather than "Assilina", Pellatispira - Biplanispira faunas found at low latitudes (Lunt 2003). In fact the Eocene fauna here is special in that it contains exmples of the radiation of Heterostegines that occured in T.b Letter Stage, specifically Grzybowskia, a form found at intermediate latitudes in the Eocene of Europe. The image here shows examples of this genus with the arcuate to polygonal rows of secondary chambers in the adult stage which resemble Heterostegina, yet are distinct, and restricted to T.b age sediments
