Intergeneric comparisons of the results of pyrolysis at 152. 5°C of mollusks and mixed foraminifera demonstrate that, as in fossils, mollusks and mixed foraminifera are characterized by slow racemizing genera (protothaca, Mercenaria and mixed foraminifera) and a fast racemizing genus (Macoma). The functions describing the rate of racemization of leucine in all heated material duplicated the non-linear form of the rate curve previously documented in fossils and other heating experiments. The initial rate constants followed the extended linear form seen in the pyrolysis experiments. An activation energy of 27.4 kcal/mole was calculated for the racemization of leucine in the total Mercenaria sample. Intrageneric racemization rates in fossils were reproduced by pyrolysis which indicates that the concerted hydrolysis mechanism occurring in fossils is also the directing force during pyrolysis. The initial and subsequent rate constants in the high molecular weight fraction (molecular weight greater than 640) of heated Mercenaria were strongly influenced by the hydrolysis/racemization of amino acids with stable peptide bonds such as aspartic acid. The use of pre-packed Sephadex columns for gel filtering the total sample produced consistent, reproducible trends in the high (greater than 640 molecular weight) and low (lower than 640 molecular weight) molcular weight fractions. Tivela and Chione from terraces along the Pacific Coast of Baja California Sur produced four groups of D/L valine and leucine ratios corresponding to oxygen isotope stages 5, 7, 9, or higher; and the high mean annual temperature of the region dictates that only valine and leucine can be used to resolve amino acid ages. However, even those amino acids were racemic in samples at least 300,000 years. Amino acid ages for Epilucina and Tivela from terraces on San Miguel Island, Channel Islands include: 102,000 + 19, 000 years (23 m), 16,000 348,000 + 64,000 years (84 m), 54,000 404, 000 + 74,000 years (88 m) and 63,000 456,000 + 83,000 years (131 m). 71,000 Analyzed Epilucina frequently produced anomalous D/L ratios whereas Tivela was consistently reproducible. Racemization studies of well-preserved bone samples from Natural Trap Cave, Wyoming, indicated that the samples do not conform to trends expected from their chrono-stratigraphic position. Their anomalously high, variable rate constants combined with data on molecular weight distribution of D/L ASP indicate that non-thermal diagenesis has significantly altered the amino acids in these samples. -- AATA