PALEOENVIRONMENTS OF THE HYDE PARK, NEW YORK, MASTODON SITE, BASED ON SUBFOSSIL COLEOPTERAN REMAINS

The Hyde Park Mastodon of eastern New York State is a 90% complete, 11,500-year-old specimen that was excavated in 2000, after being discoved during excavation of a small wetland. Skeleton matrix sediments were not available in stratigraphic context, so samples were recovered from an undisturbed sequence in a trench excavated in the margin of the bone-bearing basin. Approximately 500 g. of peat and calcareous mud was screen-washed and examined from each of nine 10-cm-thick slabs through the section.

Subfossil insect remains were recovered from each sample, although abundances are correlated with organic content and decreased with depth in the section. Few were sufficiently complete to be identifiable to the species level, and there was insufficient differentiation between samples to allow detection of any temporal trends in the fauna. Species composition of the fauna is consistent with a small pond with emergent herbaceous vegetation and mammalian dung.

Species that have been identified in the fauna include Amara alpina, a ground beetle normally considered a tundra indicator but associated in the sediments with needles of both black and white spruce. Also present are the leaf-feeding beetles Orsodacne atra and Plateumaris sp.; the former commonly feeds on Salix, and the latter on emergent Cyperaceae. A species particularly indicative of climate is the rove beetle Tachinus nearcticus, whose southern limit today in eastern North America occurs in central Labrador and northern Quebec. Numerous fragments of the dung beetles Aphodius and Aegialia imply presence of mammalian herbivore dung; a rich and diverse aquatic insect fauna is also suggestive of a lack of fish in the basin.

The environment suggested by the Hyde Park beetle fauna is consistent with conditions at modern treeline in northern Quebec and Ontario, with July temperatures 7-8 degrees C colder than those typical of Hyde Park today.