ECOLOGICAL CONTEXTS OF CARBONIFEROUS VERTEBRATE COPROLITE ICHNOFAUNAS IN WESTERN NORTH AMERICA AND SCOTLAND

Western North America yields the best described vertebrate coprolite ichnofaunas. Principal ichnofaunas include: (1) Lower Mississippian Bear Gulch Lagerstätte, MT; (2) Upper Pennsylvanian Weber Formation, CO; (3) Upper Pennsylvanian Belden Formation, CO; (4) Upper Pennsylvanian Altrasado Formation – Kinney Brick Quarry and Tinajas Lagerstätten and Erickson site, NM; and (5) Upper Pennsylvanian Beeman Formation, NM.

The four bromalite faunas of Missourian age in New Mexico represent an ecological transect from lacustrine to basinal marine: (1) Tinajas Lagerstätte – lacustrine; (2) Kinney Brick Quarry Lagerstätte – lagoonal; (3) Erickson site – nearshore marine; and (4) Beeman Formation – offshore marine. There are clear trends through these ichnofaunas (Tinajas-Kinney- Erickson-Beeman): (1) flattened preservation in matrix to isolated three dimensional; (2) diverse bromalites to only coprolites; and (3) increasing proportion of spiral coprolites. The ichnofaunas of the Erickson site and the Beeman Formation are representative of the Crassocoprus Ichnofacies and the Shark Surplus Paradox, in which there is an apparent disproportionate diversity and abundance of spiral (probably chondrichthyan) coprolites relative to the fish fauna (preserved or inferred).

Scotland yields large collections of Carboniferous coprolites from three Middle Mississippian (Viséan) localities: (1) East Kirkton, West Lothian; (2) Wardie, Midlothian; and (3) Anstruther, Fife. The Late Mississippian (Serpukhovian) of Bearsden, East Dunbartonshire also yields a large sample of coprolites. Smaller samples occur in several other Carboniferous localities. Ecological contexts represented in Western North America can be recognized in Scotland. Wardie and Anstruther are dominated by spiral coprolites and represent the Crassocoprus ichnofacies. East Kirkton is similar to the Tinajas Lagerstätten in preserving a wide range of morphotypes, including some spiral forms.