Late Tremadocian chitinozoans and acritarchs from northwestern Argentina (Western Gondwana)

Chitinozoans and acritarchs are recorded from the Saladillo and Parcha formations of the Pascha-Incamayo area (Salta Province), Cordillera Oriental, northwestern Argentina. These organic microfossils coexist with graptolites of the Kiaerograptus, Araneograptus murrayi and Hunnegraptus copiosus biozones of early late Tremadocian and late Tremadocian age respectively. This is the oldest chitinozoan record from western Gondwana, and one of the few Tremadocian chitinozoan assemblages documented in the world. The stratigraphical range and the palaeobiogeographic affinities of the recovered acritarchs (messaoudensis-trifidum association) and the chitinozoans assemblages are discussed at regional and at global scale. A new chitinozoan species, Euconochitina paschaensis, is described.