FLORISSANT IS BETTER THAN AMBER: A COMPARISON OF BEETLE PRESERVATION, DIVERSITY AND ECOLOGICAL REPRESENTATION

Florissant is often cited as one of the world’s great fossil insect deposits. Over 1,500 insect species have been described from the 34 million year old deposit. However, when one mentions fossil insects, most think of amber deposits. Amber is widely noted for its ability to capture high levels of diversity, for exceptional preservation and clarity of anatomical details, but is amber really the pinnacle of insect preservation that many consider it to be? To compare Florissant to amber deposits, I used a database compiled from the fossil beetle literature. Beetles are included from localities from around the world, including all beetle species described from Florissant and from all fourteen of the beetle-bearing ambers. Florissant captured greater species-level diversity than any single amber locality, as well as greater diversity than all the amber localities combined. There are 578 species described from Florissant and between one and 183 species described from any single amber locality. A tally of all amber localities yields an amber species richness of 507, 12% lower than found in Florissant alone. Family level diversity is also higher for Florissant than for any individual amber site. There are 53 families preserved at Florissant, while the amber locality with the greatest family level diversity (Saxon Amber) has only 44 families recorded. Florissant and the amber deposits differ greatly in the size classes they preserve and in the ecology of the taxa that are captured. Florissant captures a wider range of size classes (1-24mm) and beetles average 6.7mm. Amber preserves fewer size classes (1-12.8mm) and the average size is 3.45mm. There are also differences in the ecology of the taxa captured at Florissant and in the amber deposits. Florissant has a good representation of aquatic groups, which are mostly absent from amber deposits. The ambers tend to capture wood-inhabiting groups, which are much less common in Florissant. Amber is often thought of as the ideal mode of preservation for fossil insects. However, the rich deposits of the Florissant Fossil Beds show greater levels of diversity, a wider range of size classes preserved and an ecological representation that differs from the amber deposits. For fossil beetle diversity, Florissant is better than any single amber deposit as well as all amber deposits combined.