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


Fishes

In the Tlayua Quarry so far more than 3500 specimens of fishes have been collected, representing 50 taxa, most of them new to science. The fishes represent 75% of all the material, and Teleostei and Holostei have been found (Fig 1). Studies on the teleost fishes, like clupeomorphs, aspidorhynchids, elopids, etc., is in an initial stage, and the preliminary results will be published in the near future.

The most common holostean fishes families from Tlayua are:

Pycnodonts - In Tlayua there are at least five genera with several species. Applegate (1992) has described Tepexichthys aranguthyorum and is working on the description of two more. Nowadays, this family inhabits coral reefs so Tlayua, during the Cretaceous must be a coral barrier reef.

Macrosemids - Before the discovery in Tlayua, these fishes had only been reported from Europe. Therefore, the discovery by MSc student Katia Gonzalez of macrosemiids was the first of its kind in the New World. She described one new species of the genus Notagogus and a further two new genera.

Amiforms - Many specimens from this group have been collected, among them some of the larger specimens reported from Tlayua Quarry. Dr. Lance Grande, from the Chicago Field Museum will publish a paper on the amiids of the world, including a taxon of Tlayua that will be described as a new genus.

Ophiopsids - Another species described by Applegate (1998) is Teochthys kallistos, a member of this family. From this family only three species have been described in the New World, including the Tlayua material.

Ichthyodectiforms - Primitive teleosts of uncertain taxonomic position, under study by Biol. Jesus Alvarado.

Aspidorhynchidae - The so-called pipe fishes are represented in Tlayua by two genera.

Sarcopterygii - This finding (only one specimen) is very important because it represents the first coelacanth fish, Axelcodichthys, in Mexico. MSc. Luis Espinosa (1996) has studied this material and emphasizes the affinity with the coelacanths of the Santana Formation in Brazil.

Fig. 1 Diversity of fish families discovered in Tlayua. (Based on Applegate, 1996).

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