Boundstones only 35 % of section.
Other are grain- and packstones.
Rudists strongly dominating. 
6 % of reef builders are corals.

Abstract of ref. 757:
The macrofaunal distribution of the mid-Cretaceous El Abra Limestone reef core is quantified from two measured sections in Taninul Quarry, San Luis Potosi, central Mexico. The faunal structure is transitional between typical Lower Cretaceous reefs dominated by corals with low density rudist bivalve packing. And densely-packed, rudist-dominated
Upper Cretaceous reefs. The macrofauna is predominantly associations of unconnected individuals of caprinid rudists,  with a low diversity of other shelly mollusks and corals. An examination of the alternation of paleocommunities defined  by the dominant caprinid taxa corals. An examination of the alternation of paleocommunities defined by the dominant  caprinid taxa reveals no pattern of biotic succession within the reef core. Large-scale sedimentologic features of mud  and debris content, coupled with rudist growth type, suggest that paleocommunities may have been physically controlled. 