afrotheria
Afrotheria ( from Latin ''Afro-'' "of Africa" + ''theria'' "wild beast") is a clade of mammals, the living members of which belong to groups that are either currently living in Africa or of African origin: golden moles, elephant shrews (also k ...
n mammals. Although there are many fossil species, the only species surviving today is the
aardvark
The aardvark ( ; ''Orycteropus afer'') is a medium-sized, burrowing, nocturnal mammal native to Africa. It is the only living species of the order Tubulidentata, although other prehistoric species and genera of Tubulidentata are known. Unlik ...
, ''Orycteropus afer''. Orycteropodidae is recognized as the only family within the order Tubulidentata (Latin: "tube" (tubulis), "tooth" (dentis)), so the two are effectively synonyms.
Evolution
The first aardvark fossil discovered was originally named ''Orycteropus gaudryi'' (now '' Amphiorycteropus'') and was found in
Turolian
The Turolian age is a period of geologic time
The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the pr ...
deposits on the island of
Samos
Samos (, also ; el, Σάμος ) is a Greek island in the eastern Aegean Sea, south of Chios, north of Patmos and the Dodecanese, and off the coast of western Turkey, from which it is separated by the -wide Mycale Strait. It is also a sepa ...
. Since then, representatives of the order Tubulidentata have been located from the
Oligocene
The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but t ...
in what is now Europe, and it is believed that the order probably originated around 65–70 million years ago or in the
Paleocene
The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''pala ...
. They are thought to be closely related to the now extinct
Ptolemaiida
Ptolemaiida is a taxon of wolf-sized afrothere mammals that lived in northern and eastern Africa during the Paleogene. The oldest fossils are from the latest Eocene strata of the Jebel Qatrani Formation, near the Fayum oasis in Egypt. A tooth is ...
, a lineage of carnivorous afrotheres. The family arose in Africa in the Early
Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
epoch, and spread to Eurasia later in the Miocene. Most of the family's diversity had become extinct by the end of the
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58
Characteristics
Aardvarks had originally been categorized as relatives of American anteaters in the order Edentata. But their unique type of teeth and other morphological characteristics had made it clear that aardvarks are not closely related to any other living mammals. Since the end of the 19th century, they are placed in their own separate order Tubulidentata. Both the fossil record and genetic studies have corroborated that separate status. All similarities to American anteaters have evolved independently as adaptations to eating ants.
One of the most distinctive features of the animals is that their teeth have a "tubulidentate" microstructure, lacking enamel, and are just rounded structures of dentine. They lack incisors and canines, and have 20–22 teeth, which are evergrowing, unrooted, and
diphyodont A diphyodont is any animal with two ss of teeth, initially the '' deciduous'' set and consecutively the '' permanent'' set. Most mammals are diphyodonts—as to chew their food they need a strong, durable and complete set of teeth.
Diphyodonts cont ...
. Another unique trait is that their small milk teeth are lost before the animal is born.
A few anatomical characters unite the Orycteropodidae and Tubulidentata. The occipital region of the skull has extensive
mastoid
The mastoid part of the temporal bone is the posterior (back) part of the temporal bone, one of the bones of the skull. Its rough surface gives attachment to various muscles (via tendons) and it has openings for blood vessels. From its borders, ...
exposure, the
femur
The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates ...
has a
pectineal tubercle
Pectineal may refer to:
* Musculi pectinati of the heart, also known as pectinate muscles
*Pectineus muscle, an adductor of the thigh
*Pectineal line (femur)
*Pectineal line (pubis), also known as the pecten pubis
*Pectineal ligament
The pectine ...
tibia
The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it conn ...
is curved mediolaterally.
Modern aardvarks are polygynous, the females providing care for the young. They are territorial, and only cross paths to breed. The males' genitals create a musk while females create this musk from glands in their elbows, this scent helps mating occur. The gestation period lasts about seven months, and they are dependent upon the mother until they are six months of age, becoming sexually mature at two years of age. Breeding occurs once a year, they produce one offspring, and will have maybe one to two more in their lifetime. Aardvarks are
myrmecophagous
Myrmecophagy is a feeding behavior defined by the consumption of termites or ants, particularly as pertaining to those animal species whose diets are largely or exclusively composed of said insect types. Literally, myrmecophagy means "ant eating" ...
, feeding almost exclusively on termites and ants. They rely on their sense of smell to find most of their food and hunt at night.
type species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specim ...
Aardvark
The aardvark ( ; ''Orycteropus afer'') is a medium-sized, burrowing, nocturnal mammal native to Africa. It is the only living species of the order Tubulidentata, although other prehistoric species and genera of Tubulidentata are known. Unlik ...