An abundant and well-preserved molluscan fauna from the Marquez Shale Member of the Reklaw Formation in East and Central Texas contains more than 188 species of molluscs, of which 123 are referred to new species, 6 to new subspecies, and 38 can be referred to previously described forms. A further 16 can only be generically assigned. Four new genera and two new subgenera are defined. The majority of specimens came from two localities, Joe Taylor Branch of Two Mile Creek in Milam County, and Ridge Creek in Bastrop County. Two suites of specimens from the Texas Memorial Museum and the Philadelphia Academy of Natural Sciences respectively were also examined, as labels indicated Reklaw age. Both of these suites were collected in the 1890's, and although possibly collected in the Reklaw formation, it is believed they are more likely to have come form the Queen City or Weches formations; they are also treated in the text.

The character of the deposits and the conditions under which the associated fauna of corals, bryozoans, vermes and vertebrate remains is found, suggest a near-shore, open marine environment. The fauna is a mixture of lagoonal elements, some with signs of wear, an open sea, near-shore component, and a very well-preserved, size-sorted marine component from deeper water. A few brackish water species and one possible fluviatile species could indicate the proximity of estuarine conditions. Most of the new species and genera were found in several exposures in Joe Taylor Branch of Two Mile Creek. Many of these localities were not previously known to be fossiliferous. The stratigraphy of several sections is described on Joe Taylor Branch.  All previously described fossiliferous localities of the Marquez Shale Member of the Reklaw Formation were revisited, and collections made if possible. 

Issue: BAP 352

Year published: 1996