MODERN VERTEBRATE TRACKS FROM COASTAL LITHUANIA: REGIONAL DISTRIBUTION AND TAPHONOMIC FACTORS

The formation and preservation of vertebrate traces in modern settings provides a useful guide to locating and analyzing their counterparts in sand-dominated coastal and aeolian sequences. A diverse suite of vertebrate footprints along the Baltic Sea coast offers insights into the distribution and preservation potential of tracks in sandy substrates. At the mainland beach site of Butinge, northernmost Lithuania, artiodactyl (deer) and mustelid (?) tracks occur behind the foredune ridge, with canid (fox) tracks found in association with deep excavations in back dunes. At the southernmost Curonian Spit site, three types of avian footprints occur on the high-energy Baltic Sea beach, along the low-energy Curonian Lagoon shoreline, and on a 50-m-high slipface of the active Parnidis Dune. Mammal traces along the lagoon shoreline include numerous canid tracks (also found on nearby steep dune slopes), suid (wild boar) trackways and trampled surfaces, and a few mustelid footprints. Shore-perpendicular aquatic rodent trackways, drag traces, and gnaw marks suggest that beaver activity is more prominently displayed than that of a recently introduced muskrat. Cervid (elk and deer) trackways follow trails across high vegetated dunes. Based on the wide use of horses on the spit for at least 700-800 years, their hoofprints may be preserved in the shallow subsurface of dune and beach sequences. The habitat preferences result in a predictable distribution of track assemblages allowing differentiation between the open sea vs. lagoon shoreline, stable vs. active dunes, and coastal forest (palve). The medieval phase of dune reactivation contains deformation structures interpreted as tracks with marginal ridges. Although scientific names are not used for modern tracks, once preserved in plan view of cross-section, it is reasonable to apply Vialov’s (1966) ichnotaxonomy to those footprints which readily resemble their recent counterparts and have been used for some Cenozoic tracks (Canipeda, Cervipeda, Hippipeda, Mustelipeda, Suipeda, etc.). Surface moisture, occasional freezing, rapid aeolian burial, and lithological anomalies (heavy-mineral concentrations) increase the preservation potential of tracks. Once buried, the attitude of trackways with respect to bedding surfaces determines their ultimate context.