Palaeoryctidae
Encyclopedia
Palaeoryctidae is an extinct group of relatively non-specialized placental mammals
that strived in North America
during the late Cretaceous
and took part in the first placental evolutionary radiation
together with other early mammals such as the leptictids
.
found in New Mexico
, it is known that palaeoryctids were small, shrew
-like insectivore
s with an elongated snout similar to that of the Lepticids. However, in contrast to the latter, little is known about palaeoryctids postcranial anatomy (the skeleton without the skull).
Where the leptictids were short-lived, the paleoryctids seem to have been ancestors of Eocene
species. While their dental morphology still indicate a mostly insectivorous diet, it, to some extent, also relate to Eocene carnivores such as creodonts
.
Palaeoryctidae was originally assigned to the now-abandoned grouping Insectivora
by Sloan and Van Valen (1965) and more recently to Eutheria
by Scott et al. (2002). Sister groups include: Kennalestidae, Nanocuridae, Pantolestidae
, and Zalambdalestidae.
Eutheria
Eutheria is a group of mammals consisting of placental mammals plus all extinct mammals that are more closely related to living placentals than to living marsupials . They are distinguished from noneutherians by various features of the feet, ankles, jaws and teeth...
that strived in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
during the late Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
and took part in the first placental evolutionary radiation
Evolutionary radiation
An evolutionary radiation is an increase in taxonomic diversity or morphological disparity, due to adaptive change or the opening of ecospace. Radiations may affect one clade or many, and be rapid or gradual; where they are rapid, and driven by a single lineage's adaptation to their environment,...
together with other early mammals such as the leptictids
Leptictida
Leptictida is an extinct order of placental mammals. According to cladistic studies, they may be related to Euarchontoglires , although they are more often regarded as the first branch to split from basal eutherians.- Description :The leptictids are a characteristic example of the...
.
Description
From a near-complete skull of the genus PalaeoryctesPalaeoryctes
Palaeoryctes is an extinct genus of mammal from Middle to Late Palaeocene of North America.Palaeoryctes resembled a modern shrew, being slender and sharp-nosed, with typical insectivore teeth. It was around long, and weighed around . Palaeoryctes or its relatives may have evolved into the large...
found in New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
, it is known that palaeoryctids were small, shrew
Shrew
A shrew or shrew mouse is a small molelike mammal classified in the order Soricomorpha. True shrews are also not to be confused with West Indies shrews, treeshrews, otter shrews, or elephant shrews, which belong to different families or orders.Although its external appearance is generally that of...
-like insectivore
Insectivore
An insectivore is a type of carnivore with a diet that consists chiefly of insects and similar small creatures. An alternate term is entomophage, which also refers to the human practice of eating insects....
s with an elongated snout similar to that of the Lepticids. However, in contrast to the latter, little is known about palaeoryctids postcranial anatomy (the skeleton without the skull).
Where the leptictids were short-lived, the paleoryctids seem to have been ancestors of Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
species. While their dental morphology still indicate a mostly insectivorous diet, it, to some extent, also relate to Eocene carnivores such as creodonts
Creodonta
The creodonts are an extinct order of mammals that lived from the Paleocene to the Miocene epochs. They shared a common ancestor with the Carnivora....
.
Taxonomy
The relationship between this archaic group and other insectivorous mammals is uncertain.Palaeoryctidae was originally assigned to the now-abandoned grouping Insectivora
Insectivora
The order Insectivora is a now-abandoned biological grouping within the class of mammals...
by Sloan and Van Valen (1965) and more recently to Eutheria
Eutheria
Eutheria is a group of mammals consisting of placental mammals plus all extinct mammals that are more closely related to living placentals than to living marsupials . They are distinguished from noneutherians by various features of the feet, ankles, jaws and teeth...
by Scott et al. (2002). Sister groups include: Kennalestidae, Nanocuridae, Pantolestidae
Pantolestidae
Pantolestidae is an extinct family of semi-aquatic, placental mammals that took part in the first placental evolutionary radiation together with other early mammals such as the leptictids....
, and Zalambdalestidae.