Wessex Formation

Wessex Formation Stratigraphic range: Barremian, 130–126 Ma PreЄ Є O S D C P T J K Pg N ↓
The Undercliff near Shalcombe, Isle of Wight
Type	Geological formation
Unit of	Wealden Group
Underlies	Vectis Formation
Overlies	Lower Wealden Clay Formation
Location
Region	England
Country	UK

The Wessex Formation is a fossil-rich English geological formation that dates to the Barremian stage (about 130 million years ago) of the Early Cretaceous. It is part of the Wealden Group and underlies the younger Vectis Formation.

Invertebrates are commonly preserved in the Wessex Formation. Freshwater bivalves can be found including unionoids such as Margaritifera, Nippononaia, and Unio. These bivalves are helpful in reconstructing what the freshwater paleoenvironment may have been like during the formation's deposition. Specimens of Viviparus, a genus of freshwater snail, have also been found. Cretamygale chasei, a species of Mygalomorph spider, has been described from a specimen found in amber. It is believed to be the oldest known Nemesiid and the second oldest Mygalomorph.

Hybodus

H. basanus

Hylaeobatis

H. problematica

Palaeoscyllium

Indeterminate

Vectiselachos

V. ornatus

Caturus

Indeterminate

Coelodus