Recent vertebrate tracks in sandy substrates and their paleoenvironmental implications: examples from coastal Lithuania

Abstract

A diverse suite of vertebrate footprints documented along the coast of Lithuania offers insight into the distribution and preservation potential of tracks in sandy substrates. Whereas ichnotaxonomy is not conventionally applied to modern tracks, a case is made for using footprint classification based on Vialov’s (1966) nomenclature to both observed and predicted track distribution based on extramorphological characteristics of the tracemaker. Along a barrier spit (Curonian Spit) and mainland shoreline (Būtingė) sites, two general types of avian footprints (Avipeda sp), as well as three carnivore (Bestiopeda), four ungulate (Pecoripeda, Suipeda, Hippipeda), and two rodent (Rodentipeda) track morphotypes are described. The habitat preferences result in a predictable distribution of track assemblages with a potential of differentiating vertebrate ichnofacies (lagoon shoreline, open sea beach, dunes). The moisture content, possibility of freezing and rapid aeolian burial, and lithological anomalies (e.g., heavy-mineral concentrations) enhance the preservation potential of tracks. Once preserved, the attitude of trackways in respect to bedding surfaces determines their integrity and here a model of potential regional track distribution is proposed. Track formation and preservation in modern settings provides a useful guide to locating and studying vertebrate footprints and other traces in sand-dominated coastal and aeolian sequences.