Name: Tlayúa Location: Mexico Age: Early Cretaceous (100 mya)

Taphonomy

With the geological and palaeontological information collected over more than 14 years in the Tlayua quarry, a palaeoecological model has been developed as a framework to better understand the conditions under which the Lagerstatte was formed.

The model includes al least six distinct areas, adjacent or near to the deposit:

1. To the west of the deposit, there was land (Acatlandia) and was the source of the iron-rich clays, responsible for the red-orange color (due to hematite) of Tlayua's sediments and for the terrestrial organisms present in the palaeobiota.
2. Adjacent to the land was Tlayua's lagoon, where the fossiliferous beds and all organisms derived from several environments, were deposited.
3. East of Tlayua was a large bio-rich reefal lagoon, with all the life forms present in this biotope; these form the major bulk of the biota with the other reef inhabitants.
4. Indirect evidence calls for a barrier separating the calmed and often stagnant waters of Tlayua from high energy and teeming bio-rich lagoon. This barrier was breached only during the time of storms or very high tides, rafting the organisms from the other environments.
5. The great barrier reef, located to the east of the bio-rich lagoon.
6. The open oceanic waters, that correspond to the western portion of the Tethys Ocean and are represented in the Tlayua assemblage by algae, ammonites, crinoids, and fishes that show pelagic adaptations.