The Oldest Beetle and Bee Ichnofossils from Mexico and their Paleoenvironmental Implications

摘要

Specimens of Fictovichnus gobiensis, Celliforma curvata, Celliforma rosellii, Celliforma germanica and Celliforma isp. were collected from paleosol horizons in a fluviolacustrine succession near Santiago Yolomecatl town, in northwestern Oaxaca, southern Mexico. These ichnofossils represent the oldest evidence of beetles and bees in Mexican localities. K-Ar ages and the record of the equid Miohippus assiniboiensis, an index fossil, indicate that the age of the deposits is late Eocene. Based on the presence of the insect ichnofossils, pedogenic carbonate isotopes and mammal proxies, the inferred type of vegetation present in the study area was scrubland/woodland, within subhumid to subarid conditions.