Article Title

Differential Preservation of Fossil Elements in the Maricopa Brea, California





First Page


Last Page



Maricopa is a southern California tar seep with representative flora and fauna of the Pleistocene and Recent periods. Of the over 4000 fossil elements collected in this study, there were many that represented mammals and birds of the last 30,000 years. An analysis of the recovered skeletal remains shows a differential preservation of appendicular to axial bones. In addition, the standard 9% representation of carnivores to herbivores was not found, instead, carnivores represented 17% of that consumer class. The mechanism for these statistically significant findings is the tar seep itself. Animals would become trapped in the seep; their arms and legs buried in the tar while their spine and skull remain exposed for carnivores to consume. This resulted in more appendicular skeletal remains than axial had the entire animal been preserved. The carnivores them- selves would then become trapped, attracting more carnivores, resulting in a dis- proportionate representation of that consumer class in the fossil matrix. Statistical analysis involve nonparametric analysis utilizing Chi-squared, G-Test and G-adjusted (Williams adjustment).