Plethodus

Plethodus is an extinct genus of marine bony fish belonging to the Ichthyodectiformes order. These fish lived during the Late Cretaceous period. Plethodus fossils have been found in various locations, including North America, Europe, and the Middle East, indicating a widespread distribution.

Plethodus is characterized by its distinctive dentition, possessing numerous small, conical teeth arranged in rows on the premaxilla and dentary bones. These teeth were likely used for grasping small prey items in the water column. The size of Plethodus species varied, with some reaching lengths of over a meter.

The systematic placement of Plethodus within the Ichthyodectiformes has been subject to some debate, with varying phylogenetic analyses placing it in different positions relative to other genera in the order. However, its overall morphology and the characteristics of its dentition consistently place it within this group of extinct, specialized teleost fish.

The ecological role of Plethodus is generally interpreted as that of a planktivorous or small-prey feeder in marine environments. The abundance of Plethodus fossils in some Cretaceous deposits suggests that it was a relatively common component of Late Cretaceous marine ecosystems.