There are points where fossils appear; these places are known as “reservoirs”. The Sierra Gorda, approximately 100 million years ago, consisted of low depth littoral, the Madroño is a fossil deposit of vital importance.
This place is located in the vicinity of the town of the same name, approximately 50 km from Jalpan, in the direction to Xilitla, San Luis Potosi. Here, in this majestic place, it is possible to see fossils of invertebrates that includes a large number of species already identified, but there are still more that have not been properly studied since the research process of this place has not yet been completed.
This deposit is a unique place in Mexico since it has a great abundance of remains with a great diversity and exceptional state of conservation. In most of Mexico and the world, fossil remains have been included in hard and massive rocks so that in order to study them it is necessary to obtain thin slabs to analyze a single specimen in which a large number of cuts are required in different directions without ever being able to extract a complete specimen, which makes it difficult to have more information about them.
However, in the fossil deposits of the Madroño, the limestone in which they are included have degraded and allows to see each specimen complete and in third dimension so that it is possible to appreciate the external structure and occasionally the internal structure of each specimen.