LAURUSSIAN-ASPECT OF THE COPROLITE ASSOCIATION FROM THE UPPER TRIASSIC (CARNIAN) OF THE ARGANA BASIN, MOROCCO

Abstract

Abstract: A large collection of vertebrate coprolites derives from a debris flow conglomerate in the Upper Triassic Irohalene Member (Carnian) of the Timezgadiouine Formation, northern Argana Basin, Morocco. The coprolites are classified into 14 different morphotypes (MA to MN) based on their size, shape, and surface texture that are divided into three groups: striated coprolites; spiral and scroll-like coprolites; and non-spiral coprolites lacking striations. The great variety of morphotypes suggests the coprolites correspond to a variety of terrestrial and aquatic carnivorous producers. The carnivore coprolites lithified rapidly and were deposited in a high-energy sheetflood. The majority of the coprolites were produced by semi-aquatic and terrestrial tetrapods, with a small percentage produced by fish. The occurrence of Dicynodontocopros, common Alococopros, and some heteropolar forms with affinities to Heteropolacopros, are consistent with a late Carnian age for the Irohalene Member. The Irohalene coprolites are mostly similar to those of the coprofaunas of late Carnian age (Otischalkian–Adamanian) in the lower Chinle Group of the western United States in the co-occurrence of Alococopros and Dicynodontocopros. Significantly, this Moroccan coprofauna from Gondwana has close Laurussian relationships.