Spalacotheriidae is a family of extinct mammals belonging to the
paraphyletic
In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In ...
group '
Symmetrodonta
Symmetrodonta is a group of Mesozoic mammals and mammal-like synapsids characterized by the triangular aspect of the molars when viewed from above, and the absence of a well-developed talonid. The traditional group of 'symmetrodonts' ranges in a ...
'. They lasted from 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
Pr ...
to the
Campanian
The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campanian ...
in
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the C ...
Asia
Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...
and
North Africa
North Africa, or Northern Africa is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region, and it is sometimes defined as stretching from the Atlantic shores of Mauritania in t ...
.
Spalacotheriids are characterised by having molar teeth with three molar cusps sitting at acute angles to one another.Martin, T., 2018. 6. Mesozoic mammals—early mammalian diversity and ecomorphological adaptations. In Mammalian evolution, diversity and systematics (pp. 199-300). De Gruyter. The shape of their teeth as well as their long lower jaw indicate a
carnivorous
A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other so ...
/
insectivorous
A robber fly eating a hoverfly
An insectivore is a carnivorous animal or plant that eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects.
The first vertebrate insectivores we ...
diet.
A sub-group of Spalacotheriidae, the spalacolestines, lack a
Meckelian groove The Meckelian groove (or Meckel's groove, Meckelian fossa, or Meckelian foramen, or Meckelian canal) is an opening in the medial (inner) surface of the mandible (lower jaw) which exposes the Meckelian cartilage.modern ear anatomy.
Genera
* ''
Akidolestes
''Akidolestes'' is an extinct genus of mammals from the family spalacotheriid.
Although Akidolestes do not have any modern relatives, they are early mammals related to therians (the subclass containing marsupials and placentals). They belong ...
Symmetrolestes
''Symmetrolestes'' is an extinct genus of small spalacotheriid mammal from the Early Cretaceous period of Japan. The genus contains one species known as ''S. parvus'', the type fossil (which is only fossil known) is from fluvial deposits located ...
Yaverlestes
''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
A holotype is a single physical example (or illu ...