upright, spoon-shaped mudstickers. As described earlier, Lithiotis are found in vertically oriented "banana-bunch" clusters (Chinzei et al., 1982) with colonies starting on any available hard substrate (rocks or shells; Fig. 10D). Juve- niles most likely initially attached themselves with a bys- sus, and later cemented themselves onto older Li thiotis bi- valves. In cross section, body chambers are filled with sed- iment at varying levels. Nauss (1986, p. 72) proposed that "most of the (framework) matrix sediment was deposited after the bivalves were well established." The result was well-cemented buildups that were certainly wave-resis- tant and rose above the surrounding seaAoor (Buser and Debeljak, 1994).

Cochlearites grew similarly to Lithiotis a— vertical life position (Fig. 10K). The orientations of Cochlearites in the Assemsouk section barely deviate from upright, without the twisting so coinmon in Lithiotis buildups. There is not evidence of cementation or attachment to other clams as in Li,thiotis. Therefore, it is presumed that Cochlearites buildups were not as well cemented or wave resistant as the Lithiotis buildups and may have had less topographic relief.

In Oregon, Lithiotis-constructed buildups are laterally continuous with a buildup-flank facies bearing a phaceloid spongiomorph as well as spines and plates of regular ec¹i noids, both of which would have been organisms restricted to open-marine or at least normal-salinity conditions. Lithiotis probably needed well-oxygenated, clear waters, as it is only found in clean, calcareous facies (Posenato et al., 2000). At Assemsouk, the Cochlearites facies caps a well-developed reef containing scleractinian corals (Fig.

88). While not laterally continuous, it is likely that Coch- leari,tes also inhabited more open-marine conditions than the other "Lithiotis" facies bivalves.

Photo symbiosis