Yaverlestes gassoni is an extinct mammal which dates to the early Cretaceous period, 130 million years ago. It is part of the Wessex Formation from the Isle of Wight, England. The holotype, BMNH M 54386, is a partial jaw discovered near Yaverland.

The genus name, Yaverlestes, is derived from Yaverland, the location of its discovery, and lestes, Greek for thief. The specific epithet, gassoni, is in honour of Brian Gasson, its discoverer.

Temporal range: Early Cretaceous, 130 Ma
Restoration of Yaverlestes gassoni
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Symmetrodonta
Family: Spalacotheriidae
Genus: Yaverlestes
Y. gassoni
Binomial name
Yaverlestes gassoni
Steven Sweetman, 2008


  • Sweetman, Steven. "A spalacolestine spalacotheriid (mammalia, trechnotheria) from the early cretaceous (barremian) of southern england and its bearing on spalacotheriid evolution. Palaeontology. 51. 1367 - 1385. 10.1111/j.1475-4983.2008.00816.x.".

Eotyrannus (meaning "dawn tyrant") is a genus of tyrannosauroid theropod dinosaur hailing from the Early Cretaceous Wessex Formation beds, included in Wealden Group, located in the southwest coast of the Isle of Wight, United Kingdom. The remains (MIWG1997.550), consisting of assorted skull, axial skeleton and appendicular skeleton elements, from a juvenile or subadult, found in a plant debris clay bed, were described by Hutt et al. in early 2001. The etymology of the generic name refers to the animals classification as an early tyrannosaur or "tyrant lizard", while the specific name honors the discoverer of the fossil.

List of prehistoric mammals

This is an incomplete list of prehistoric mammals. It does not include extant mammals or recently extinct mammals. For extinct primate species, see: list of fossil primates.


Spalacotheriidae is a family of extinct mammals belonging to the group Symmetrodonta. They were a rather successful lineage, lasting from the Early Cretaceous to Campanian in North America, Europe, Asia and North Africa. The lack of a Meckelian groove indicate that they had a modern ear anatomy, and their deciduous canines and premolars as well as long lower jaw indicate a carnivorous/insectivorous diet.

Wessex Formation

The Wessex Formation is a fossil-rich English geological formation that dates from the Berriasian to Barremian stages (about 145–125 million years ago) of the Early Cretaceous. It forms part of the Wealden Group and underlies the younger Vectis Formation and overlies the Durlston Formation. The dominant lithology of this unit is mudstone with some interbedded sandstones.

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