''Tribodus'' is an extinct genus of

hybodont Hybodontiformes, commonly called hybodonts, are an extinct group of shark-like chondrichthyans, which existed from the late Devonian to the Late Cretaceous. They form the group of Elasmobranchii closest to neoselachians, the clade of modern shar ...

shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimo ...

from the

Romualdo Formation The Romualdo Formation is a geologic Konservat-Lagerstätte in northeastern Brazil's Araripe Basin where the states of Pernambuco, Piauí and Ceará come together. The geological formation, previously designated as the Romualdo Member of the Sa ...

of northeastern Brazil. It lived during the

Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pro ...

period (

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), a ...

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± 0.9 M ...

stages). This genus is known from articulated and somewhat complete specimens, from a locality known for the extraordinary preservation of the fossil remains found. ''Tribodus'' specimens have been preserved three-dimensionally, and acid-preparation methods have revealed much of the anatomy of this shark.''Tribodus'' is found to have dorsal fin-spines and head spines, though only in males.

References

{{Taxonbar, from=Q95449812 Hybodontiformes Prehistoric fish of South America Early Cretaceous animals of South America Albian life Aptian life Cretaceous Brazil Fossils of Brazil Romualdo Formation Fish described in 1989 Taxa named by Alberto Brito